Lightwave Communications Power Supply LDX 3232 User Manual

User’s Guide  
LDX-3232  
High Compliance Current Source  
ILX Lightwave Corporation · P. O. Box 6310 · Bozeman, MT, U.S.A. 59771 · U.S. & Canada: 1-800-459-9459 · International Inquiries: 406-556-2481 · Fax 406-586-9405  
ilx.custhelp.com · www.ilxlightwave.com  
70037800_R01_04_06  
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TABLE OF CONTENTS  
TABLE OF CONTENTS  
Safety Information and the Manual . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix  
General Safety Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ix  
Safety Marking Symbols . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . x  
Comments, Suggestions, and Problems . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii  
Chapter 1 Introduction and Specifications  
Product Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1  
Initial Inspection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
Installing Your LDX-3232 High Compliance Current Source . . . . . . . . . . . . . . 2  
Grounding Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
AC Line Power Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2  
GPIB Connector . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3  
The GPIB Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3  
Tilt-Foot Adjustment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3  
Operating the LDX-3232 Precision Current Source . . . . . . . . . . . . . . . . . . . . 3  
Maintenance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5  
Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6  
Available Options and Accessories . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8  
Chapter 2 Operation  
Applying Power to Your LDX-3232 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
The Power On Sequence . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9  
The Power On State . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10  
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TABLE OF CONTENTS  
Connecting to the Laser . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10  
Interlock Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12  
Photodiode Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13  
Setting the PD Bias . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13  
Grounding Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13  
Front Panel Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14  
The Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14  
Operating a Laser in Constant Current (I) Mode . . . . . . . . . . . . . . . . . . . . . . 14  
Setting Up the Precision Current Source . . . . . . . . . . . . . . . . . . . . . . . . . . . 15  
Conditions That Will Automatically Shut Off the LASER OUTPUT . . . . . . . . 17  
Operating a Laser in Constant Power (P) Mode . . . . . . . . . . . . . . . . . . . . . . . 17  
Entering Photodiode Responsivity Values . . . . . . . . . . . . . . . . . . . . . . . . . . 17  
Error Indicators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19  
Chapter 3 Remote Operation  
Reading the GPIB Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21  
Changing the GPIB Address . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21  
Changing Operation from Local to Remote . . . . . . . . . . . . . . . . . . . . . . . . . 22  
LDX-3232 Current Source Command Set . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22  
Command Syntax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22  
Command Paths . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25  
IEEE488.2 Command Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26  
LDX-3232 Frequently Used Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27  
Status Reporting . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28  
Event and Condition Registers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28  
Operation Complete Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 28  
Output Off Register . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30  
Command Timing and Completion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32  
Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32  
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TABLE OF CONTENTS  
Chapter 4 Command Reference  
LDX-3232 Device-Dependent Commands . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39  
LDX-3232 Device-Dependent Command Reference . . . . . . . . . . . . . . . . . . . . 40  
Chapter 5 Functions and Features  
Saving and Recalling from the Front Panel . . . . . . . . . . . . . . . . . . . . . . . . . . 83  
Saving and Recalling Under Remote Operation . . . . . . . . . . . . . . . . . . . . . . . 84  
Using the Laser Compliance Voltage Adjustment . . . . . . . . . . . . . . . . . . . . . 84  
Using the LDX-3232 Current Source’s Trigger Function . . . . . . . . . . . . . . . . 85  
Using the LDX-3232 Current Sources’s BNC Interlock Connection . . . . . . . 86  
BNC Interlock Usage Example . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86  
Modulating the Laser Current Source . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86  
Chapter 6 Calibration and Troubleshooting  
Calibration Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89  
Recommended Equipment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 90  
Local Calibration of the LDX-3232 Current Source . . . . . . . . . . . . . . . . . . . . 91  
Current Source Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 91  
I
Current Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 92  
PD  
Laser Forward Voltage Measurement Calibration . . . . . . . . . . . . . . . . . . . . 94  
Remote Calibration of the LDX-3232 Current Source . . . . . . . . . . . . . . . . . . 95  
Current Source Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95  
I
Current Calibration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 96  
PD  
Laser Forward Voltage Measurement Calibration . . . . . . . . . . . . . . . . . . . . 98  
Troubleshooting Guide . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 99  
Error Messages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101  
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TABLE OF CONTENTS  
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LIST OF FIGURES  
LIST OF FIGURES  
Figure 1.1 LDX-3232 Front View . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4  
Figure 1.2 LDX-3232 Rear View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4  
Figure 2.1 Common Laser Cathode - Photodiode Cathode . . . . . . . 11  
Figure 2.2 Common Laser Cathode - Photodiode Anode . . . . . . . . 11  
Figure 2.3 Common Laser Anode - Photodiode Cathode . . . . . . . . 11  
Figure 2.4 Common Laser Anode - Photodiode Anode . . . . . . . . . . 12  
Figure 2.5 Back Panel LD Connector . . . . . . . . . . . . . . . . . . . . . . . . 12  
Figure 3.1 LDX-3232 Command Path Structure . . . . . . . . . . . . . . . . 25  
Figure 3.2 LDX-3232 Status Reporting Schematic Diagram . . . . . . 29  
Figure 3.3 LDX-3232 Output Off Register . . . . . . . . . . . . . . . . . . . . 31  
Figure 4.1 Command Description Format . . . . . . . . . . . . . . . . . . . . 39  
Figure 5.1 LDX-3232 Rear Panel . . . . . . . . . . . . . . . . . . . . . . . . . . . 85  
Figure 6.1 IPD Calibration Circuit . . . . . . . . . . . . . . . . . . . . . . . . . . . 91  
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LIST OF FIGURES  
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LIST OF TABLES  
LIST OF TABLES  
Table 2.1 LDX-3232 Default Settings. . . . . . . . . . . . . . . . . . . . . . . . . 10  
Table 2.2 LDX-3232 Error Indicators . . . . . . . . . . . . . . . . . . . . . . . . . 19  
Table 3.1 Substitute Parameter Names. . . . . . . . . . . . . . . . . . . . . . . 23  
Table 3.2 LDX-3232 Often Used Commands . . . . . . . . . . . . . . . . . . 27  
Table 3.3 LDX-3232 Default Settings for Output Off Registers . . . . . 30  
Table 3.4 Error Code Classifications . . . . . . . . . . . . . . . . . . . . . . . . . 33  
Table 3.5 LDX-3232 Error Codes. . . . . . . . . . . . . . . . . . . . . . . . . . . . 33  
Table 4.1 LDX-3232 Device-Dependent Commands. . . . . . . . . . . . . 35  
Table 6.1 Recommended Test Equipment. . . . . . . . . . . . . . . . . . . . . 90  
Table 6.2 Required Calibration Components. . . . . . . . . . . . . . . . . . . 90  
Table 6.3 Error Code Classifications . . . . . . . . . . . . . . . . . . . . . . . . 101  
Table 6.4 LDX-3232 Error Codes. . . . . . . . . . . . . . . . . . . . . . . . . . . 101  
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LIST OF TABLES  
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SAFETY AND WAR RANTY INFOR MATION  
SAFETY AND WARRANTY INFORMATION  
The Safety and Warranty Information section provides details about cautionary  
symbols used in the manual, safety markings used on the instrument, and  
information about the Warranty including Customer Service contact information.  
Safety Information and the Manual  
Throughout this manual, you will see the words Caution and Warning indicating  
potentially dangerous or hazardous situations that, if not avoided, could result in  
death, serious or minor injury, or damage to the product. Specifically:  
Caution indicates a potentially hazardous situation that can result in minor or moderate  
injury or damage to the product or equipment.  
Warning indicates a potentially dangerous situation that can result in serious injury or  
death.  
WARNING  
Visible and/or invisible laser radiation. Avoid direct exposure to the beam.  
General Safety Considerations  
If any of the following conditions exist, or are even suspected, do not use the  
instrument until safe operation can be verified by trained service personnel:  
Visible damage  
Severe transport stress  
Prolonged storage under adverse conditions  
Failure to perform intended measurements or functions  
If necessary, return the instrument to ILX Lightwave, or authorized local ILX  
Lightwave distributor, for service or repair to ensure that safety features are  
maintained (see the contact information on page xiii).  
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SAFETY SYMBOLS  
All instruments returned to ILX Lightwave are required to have a Return  
Authorization Number assigned by an official representative of ILX Lightwave  
Corporation. See Returning an Instrument on page xi for more information.  
SAFETY SYMBOLS  
This section describes the safety symbols and classifications.  
Technical specifications including electrical ratings and weight are included within  
the manual. See the Table of Contents to locate the specifications and other  
product information. The following classifications are standard across all ILX  
Lightwave products:  
Indoor use only  
Ordinary Protection: This product is NOT protected against the harmful ingress of moisture.  
Class I Equipment (grounded type)  
Mains supply voltage fluctuations are not to exceed ±10% of the nominal supply voltage.  
Pollution Degree II  
Installation (overvoltage) Category II for transient overvoltages  
Maximum Relative Humidity: <80% RH, non-condensing  
Operating temperature range of 0°C to 40°C  
Storage and transportation temperature of -40°C to 70°C  
Maximum altitude: 3000 m (9843 ft.)  
This equipment is suitable for continuous operation.  
Safety Marking Symbols  
This section provides a description of the safety marking symbols that appear on  
the instrument. These symbols provide information about potentially dangerous  
situations that can result in death, injury, or damage to the instrument and other  
components.  
Caution,  
refer to  
manual  
Earth  
ground  
Terminal  
Alternating  
current  
Visible and/or  
invisible laser  
radiation  
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WAR RANTY  
Caution, risk  
of electric  
shock  
Protective  
Conductor  
Terminal  
Caution, hot  
surface  
Frame or  
chassis  
Terminal  
On: In position of a bistable push control.  
The slash (I) only denotes that mains are on.  
Off: Out position of a bistable push control.  
The circle (O) only denotes that mains are off.  
or  
(I)  
or  
(O)  
WARRANTY  
ILX LIGHTWAVE CORPORATION warrants this instrument to be free from  
defects in material and workmanship for a period of one year from date of  
shipment. During the warranty period, ILX will repair or replace the unit, at our  
option, without charge.  
Limitations  
This warranty does not apply to fuses, lamps, defects caused by abuse,  
modifications, or to use of the product for that it was not intended.  
This warranty is in lieu of all other warranties, expressed or implied, including any  
implied warranty of merchantability or fitness for any particular purpose. ILX  
Lightwave Corporation shall not be liable for any incidental, special, or  
consequential damages.  
If a problem occurs, please contact ILX Lightwave Corporation with the  
instrument's serial number, and thoroughly describe the nature of the problem.  
Returning an Instrument  
If an instrument is to be shipped to ILX Lightwave for repair or service, be sure to:  
1
2
Obtain a Return Authorization number (RA) from ILX Customer Service.  
Attach a tag to the instrument identifying the owner and indicating the required service or  
repair. Include the instrument serial number from the rear panel of the instrument.  
3
4
5
Attach the anti-static protective caps that were shipped with the instrument and place the  
instrument in a protective anti-static bag.  
Place the instrument in the original packing container with at least 3 inches (7.5 cm) of  
compressible packaging material. Shipping damage is not covered by this warranty.  
Secure the packing box with fiber reinforced strapping tape or metal bands.  
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WAR RANTY  
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Send the instrument, transportation pre-paid, to ILX Lightwave. Clearly write the return  
authorization number on the outside of the box and on the shipping paperwork. ILX  
Lightwave recommends you insure the shipment.  
If the original shipping container is not available, place your instrument in a  
container with at least 3 inches (7.5 cm) of compressible packaging material on all  
sides.  
Repairs are made and the instrument returned transportation pre-paid. Repairs  
are warranted for the remainder of the original warranty or for 90 days, thatever is  
greater.  
Claims for Shipping Damage  
When you receive the instrument, inspect it immediately for any damage or  
shortages on the packing list. If the instrument is damaged, file a claim with the  
carrier. The factory will supply you with a quotation for estimated costs of repair.  
You must negotiate and settle with the carrier for the amount of damage.  
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WAR RANTY  
Comments, Suggestions, and Problems  
To ensure that you get the most out of your ILX Lightwave product, we ask that  
you direct any product operation or service related questions or comments to ILX  
Lightwave Customer Support. You may contact us in whatever way is most  
convenient:  
Phone . . . . . . . . . . . . . . . . . . . . . . . . . . . (800) 459-9459 or (406) 556-2481  
Fax . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . (406) 586-9405  
Online FAQ: . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . www.ilxlightwave.com  
Or mail to:  
ILX Lightwave Corporation  
P. O. Box 6310  
Bozeman, Montana, U.S.A 59771  
www.ilxlightwave.com  
When you contact us, please have the following information:  
Model Number:  
Serial Number:  
End-User Name:  
Company:  
Phone:  
Fax:  
Description of what is  
connected to the ILX  
Lightwave instrument:  
Description of the problem:  
If ILX Lightwave determines that a return to the factory is necessary, you are  
issued a Return Authorization (RA) number. Please mark this number on the  
outside of the shipping box.  
You or your shipping service are responsible for any shipping damage when  
returning the instrument to ILX Lightwave; ILX recommends you insure the  
shipment. If the original shipping container is not available, place your instrument  
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WAR RANTY  
in a container with at least 3 inches (7.5 cm) of compressible packaging material  
on all sides.  
We look forward to serving you even better in the future!  
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INTR ODUCTION AND SPECIFICATIONS  
C H A P T E R  
1
Product Overview  
C H A P T E R  
1
INTRODUCTION AND SPECIFICATIONS  
This chapter is an introduction to the LDX-3232 High Compliance Current Source.  
This chapter contains first time setup information, important safety considerations,  
maintenance information, instrument specifications, and general LDX-3232  
information.  
If any of the following symptoms exist, or are even suspected, remove the LDX-3232  
from service. Do not use the LDX-3232 until trained service personnel can verify safe  
operation.  
Visible damage  
Severe transport stress  
Prolonged storage under adverse conditions  
Failure to perform intended measurements or functions  
If necessary, return the LDX-3232 to ILX Lightwave for service and repair to ensure that  
safety features are maintained.  
Product Overview  
The LDX-3232 instrument is a high compliance laser diode current source  
intended for use with quantum cascade laser diodes and other devices requiring a  
high compliance output. The LDX-3232 current source provides a high stability  
output with multiple laser protection features and a fully redundant current limit.  
The LDX-3232 offers the added benefits of dual laser interlocks and a GPIB  
interface to allow full automation of testing.  
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INTR ODUCTION AND SPECIFICATIONS  
Initial Inspection  
C H A P T E R  
1
Initial Inspection  
When you receive your LDX-3232 instrument, verify that the following items were  
shipped with the instrument:  
LDX-3232 High Compliance Current Source  
LDX-3232 Series Instruction Manual  
Power Cord  
Shipping Kit  
Installing Your LDX-3232 High Compliance Current Source  
Grounding Requirements  
The LDX-3232 High Compliance Current Source comes with a three conductor  
AC power cable. The power cable must either be plugged into an approved three-  
contact electrical outlet or used with a three-contact or two-contact adapter with  
the grounding wire connected to an electrical ground (safety ground). The  
LDX-3232's power jack and supplied power cable meet IEC safety standards.  
AC Line Power Requirements  
You can operate the LDX-3232 instrument from a single phase power source  
delivering nominal line voltages of 100, 120, 220-240 VAC (all values RMS), at  
50/60 Hz. The line power voltage can vary ±10% but cannot exceed 250 VAC.  
Maximum power consumption is 60 VA (Volt-Amps). The instrument's operational  
voltage is factory configurable and need not be changed before operating the  
instrument. However, check to be sure that the voltage printed on the back panel  
of the instrument matches the power-line voltage in your area.  
Before connecting the LDX-3232 High Compliance Current Source to a power source,  
verify that the AC power source matches the setting of the LDX-3232's voltage printed on  
the rear panel of the instrument.  
To avoid electrical shock hazard, connect the instrument to properly earth-grounded,  
3-prong receptacles only. Failure to observe this precaution can result in severe injury or  
death.  
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INTR ODUCTION AND SPECIFICATIONS  
Installing Your LDX-3232 High Compliance Current Source  
C H A P T E R  
1
GPIB Connector  
The IEEE 488 GPIB interface connector is located on the rear panel, directly  
above the power input module and fuse. See Figure 1.2, LDX-3232 Rear View.  
Attach the GPIB cable to the 24-pin connector located on the rear panel. The  
connector is tapered to ensure proper orientation. Using your fingers, tighten the  
two screws on the cable connector.  
A total of 15 devices can be connected together on the same GPIB interface bus.  
The cables have single male/female connectors on each end so that several  
cables can be stacked. This allows more than one cable to be attached to any  
one device. However, the maximum length of the GPIB cables must not exceed  
20 meters (65 feet) total or 2 meters (6.5 feet) per device.  
The GPIB Address  
The talk and listen addresses on the LDX-3232 High Compliance Current Source  
are identical. This GPIB address is read locally by pressing the (GPIB) LOCAL  
switch with the address displayed on the LED display. The instrument comes from  
the factory configured with the GPIB address set to 1. You can change the  
LDX-3232's GPIB address locally (via front panel). A procedure for changing the  
address can be found in the section "Changing the GPIB Address" in Chapter 3.  
Tilt-Foot Adjustment  
The LDX-3232 High Compliance Current Source comes standard with folding  
front legs and two rear feet for use as a bench top instrument. Extending the front  
feet so that the instrument front panel sits up makes it easier to view the LED  
displays. To use them, place the unit on a stable base and rotate the front legs  
downward until they lock into position.  
Operating the LDX-3232 Precision Current Source  
Now that the LDX-3232 High Compliance Current Source is installed and ready  
for use, you can begin to learn about its operation. The following photos show the  
functional keypad groupings, back panel connectors, and so on. Use these figures  
to familiarize yourself with the LDX-3232. After that, use Chapter 2 for  
fundamentals of operating your instrument.  
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INTR ODUCTION AND SPECIFICATIONS  
Installing Your LDX-3232 High Compliance Current Source  
C H A P T E R  
1
Adjust  
Section  
Display  
Power  
Switch  
Current Range  
Selection  
Parameter  
Selection  
Modulation Input  
Connector  
Laser Mode  
Selection  
GPIB Section  
Figure 1.1 LDX-3232 Front View  
PD Bias Adjust  
LD Connector  
GPIB Connector  
Power Cord  
Connector  
Interlock Input  
Connector  
Trigger Output  
Connector  
Fan  
Figure 1.2 LDX-3232 Rear View  
4
LDX-3232  
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INTR ODUCTION AND SPECIFICATIONS  
C H A P T E R  
1
Maintenance  
Maintenance  
You may have to return your instrument to the ILX Lightwave facility at some time  
for repair or service whether or not it is under warranty. There is a charge for  
repairs after the warranty period has expired. Contact an ILX Lightwave service  
representative for shipping instructions prior to returning the instrument. Have the  
model number, instrument serial number, and a description of the problem or  
request at the time of the call. All ILX Lightwave instruments are identified by a  
serial number located on the rear panel. The first four or five digits are the model  
number; the last four digits are unique to the instrument and identify your  
instrument specifically. A return authorization number will be given to you at the  
time of your request for repair or service. Please use this number in all  
communications concerning your instrument.  
If you need to ship your LDX-3232 High Compliance Current Source back to the  
factory for repair, be sure that the LDX-3232 is packaged in an enclosure with  
cushioning material to prevent damage to the instrument during shipment (use the  
original shipping containers and accessories if possible). Re-install the ESD  
protective caps on the rear and front panels over the connectors (9 pin D, BNC,  
and GPIB). Shipping damage is not covered under warranty.  
Attach a tag to the instrument identifying the owner and indicating the service or  
repair needed. Include the model number and serial number. We suggest that you  
insure the shipment.  
In North America, contact ILX Lightwave for return authorization and shipping  
instructions. Outside of North America, contact your ILX distributor for shipping  
information.  
For more information on how to obtain repair services, see the Safety and  
Warranty section of this manual.  
If cleaning is required, use a clean dry cloth. Do not use solvents.  
Potentially lethal voltages exist within the LDX-3232 High Compliance Current Source. To  
avoid electric shock, do not perform any of the maintenance on the instrument unless  
you are qualified to do so. Qualified service personnel are required to wear protective  
eyeglasses and anti-static wristbands while working on the LDX-3232 High Compliance  
Current Source circuit boards. High voltages are present on and around the instrument’s  
printed circuit boards.  
04_06  
LDX-3232  
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INTR ODUCTION AND SPECIFICATIONS  
Specifications  
C H A P T E R  
1
Specifications  
LDX-3232  
1
Drive Current Output  
Output Current Range  
0 to 2000 mA  
40 µA  
0 to 4000 mA  
2
Setpoint Resolution  
80 µA  
Setpoint Accuracy (% of FS)  
Compliance Voltage  
±0.05%  
±0.05%  
0 - 15 V, adjustable  
<100 ppm/°C  
<20 ppm  
0 - 15 V, adjustable  
<100 ppm/°C  
<20 ppm  
Temperature Coefficient  
3
Short Term Stability (1 hour)  
Long Term Stability (24 hours)  
4
<40 ppm  
<40 ppm  
5
Noise and Ripple (µA rms)  
<20 µA  
<20 µA  
<40 µA  
<20 µA  
High Bandwidth Mode  
Low Bandwidth Mode  
Transients  
6
<4 mA  
<8 mA  
<4 mA  
<8 mA  
Operational  
7
1 kV EFT/Surge  
Compliance Voltage Adjust  
Range  
0 - 15 V  
10 mV  
±20%  
0 - 15 V  
20 mV  
±40%  
Resolution  
Accuracy  
Drive Current Limit Settings  
Range  
1 to 2020 mA  
10 mA  
1 to 4040 mA  
20 mA  
Resolution  
Accuracy  
±20 mA  
±40 mA  
Photodiode Feedback  
Type  
Differential  
0 - 5V, adjustable  
5 to 10,000 µA  
±0.02%  
Differential  
0 - 5V, adjustable  
5 to 10,000 µA  
±0.02%  
PD Reverse Bias  
PD Current Range  
8
Output Stability  
Accuracy, setpoint (% of FS)  
External Analog Modulation  
Input  
±0.05%  
±0.05%  
0 - 10 V, 1 kΩ  
0 - 10 V, 1 kΩ  
Transfer Function  
200 mA / V  
400 mA / V  
6
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INTR ODUCTION AND SPECIFICATIONS  
C H A P T E R  
1
Specifications  
LDX-3232  
9
Bandwidth (3 dB)  
DC to 250 kHz  
DC to 10 kHz  
DC to 250 kHz  
DC to 10 kHz  
High Bandwidth  
Low Bandwidth  
Trigger Output  
Type  
TTL  
TTL  
Pulse Width  
13 µs  
12 ms  
13 µs  
12 ms  
Delay  
Measurement (Display)  
Output Current Range  
Output Current Resolution  
0 to 2000.0 mA  
0.1 mA  
0 to 4000.0 mA  
0.1 mA  
10  
Photodiode Current Range  
Photodiode Current Resolution  
Photodiode Current Accuracy  
0 to 10,000 µA  
1 µA  
0 to 10,000 µA  
1 µA  
±4 µA  
±4 µA  
11  
PD Responsivity Range  
0.00 to 1000.00 µA/mW  
0.01 µA/mW  
0.00 to 5000.0 mW  
0.1 mW  
0.00 to 1000.00 µA/mW  
0.01 µA/mW  
0.00 to 5000.0 mW  
0.1 mW  
PD Responsivity Resolution  
Optical Power Range  
Optical Power Resolution  
Forward Voltage Range  
Forward Voltage Resolution  
0.000 to 10.000 V  
1 mV  
0.000 to 10.000 V  
1 mV  
12  
Forward Voltage Accuracy  
±2 mV  
±2 mV  
General  
Size (H x W x D)  
Weight  
4” x 8.5” x 13.4”; 102 mm x 216 mm x 340 mm  
~ 20 pounds (9 kg)  
Power  
100/120/230-240 V~; 2/2/1A 50/60 Hz  
0°C – 40°C operating; -40°C – 70°C storage  
< 90% relative humidity, non-condensing  
Temperature  
Humidity  
Laser Safety Features  
Key switch, interlock and output delay (meets CDRH US  
21 CFR 1040.10)  
Display Type  
5-digit, green LED  
Notes  
1. All values relate to a one-hour warm-up period at room temperature, 25°C.  
2. Based on resolution of digital-to-analog converters used in the design.  
3. Over any 1-hour period, half-scale output.  
4. Over any 24-hour period, half-scale output.  
5. Measured electrically with a 1 ohm load at half-scale output; evaluating spectral noise density over a 150kHz bandwidth from  
125kHz to 275 kHz.  
6. Maximum output current transient from normal operational situations (e.g., power on-off, current on-off), as well as accidental  
situations (e.g., power line plug removal).  
7. Maximum output current transient resulting from a 1000 V power-line transient spike. Tested to ILX Lightwave Technical Standard  
#LDX-00196.  
04_06  
LDX-3232  
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INTR ODUCTION AND SPECIFICATIONS  
Specifications  
C H A P T E R  
1
8. Maximum monitor photodiode current drift over any 30 minute period. Assumes zero drift in responsivity of photodiode.  
9. 50% modulation at mid-scale output. Higher bandwidth is possible with smaller magnitude modulation signal.  
10.Similar resolution available over GPIB.  
11.Responsivity value is user-defined and is used to calculate the optical power.  
12.Four wire voltage measured at the load. Voltage measurement accuracy while driving calibration load. Accuracy is dependent  
upon load and cable used.  
Available Options and Accessories  
Options and accessories available for the LDX-3232 High Compliance Current  
Sources include the following:  
DESCRIPTION  
MODEL NUMBER  
LNF-320  
Noise Filter  
Current Source Interconnect Cable (terminated)  
Current Source Interconnect Cable (unterminated)  
DIL Laser Diode Mount  
CC-305S  
CC-306S  
LDM-4982  
LDM-4894  
LDM-4442  
RM-139  
Butterfly Laser Diode Mount  
High Power Laser Diode Mount  
Single Rack Mount Kit  
Dual Rack Mount Kit  
RM-140  
Other laser diode mounts are available. Please contact ILX Lightwave for information on  
additional options for your application.  
Our goal is to make the best laser diode instrumentation available anywhere. To  
achieve this, we need your ideas and comments on ways we can improve out  
products. We invite you to contact us at any time with your suggestions.  
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OPERATION  
Applying Power to Your LDX-3232  
C H A P T E R  
2
C H A P T E R  
2
OPERATION  
This chapter introduces you to the operation of the LDX-3232 High Compliance  
Current Source. It offers instructions for connecting your laser to the current  
source and describes powering up the instrument. This chapter also contains step  
by step procedures that teach you how to operate your current source in Constant  
Current Mode and Constant Power Mode. We recommend that you review the  
contents of this chapter at a minimum before operating the LDX-3232 Current  
Source.  
Applying Power to Your LDX-3232  
To turn on the LDX-3232, rotate the key in the "POWER"  
section of the front panel from "O" to "I". This action will initiate  
the power on sequence. If the LDX-3232 does not appear to  
turn on, verify that it is connected to line power. If line power is  
not the problem, remove the power cord and check the voltage  
selection block in addition to the line power fuse.  
The Power On Sequence  
During the power-up sequence, the following takes place. For about three  
seconds all indicators light up, and all of the 7-segment displays indicate "8". Then  
all lamps are turned off for three seconds. Next, the firmware version will be  
displayed. Then, a self-test is performed to ensure that the instrument's hardware  
and processor are communicating. After this test, the instrument is ready to  
operate and is configured to the state it was in when the power was last shut off.  
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OPERATION  
Connecting to the Laser  
C H A P T E R  
2
The Power On State  
You can choose to "clear" the last saved state by recalling the default values.  
These values are stored in BINS to that you can save or recall instrument  
configurations (described in more detail in Chapter 5). "BIN 0" contains all of the  
default configurations listed in Table 2.1.  
Note: If the instrument cannot successfully complete the power on test, an error message  
of E-512 or E-513 will be displayed on the Display. See Chapter 3 for a list of error codes  
and actions to take when your instrument indicates these errors.  
Table 2.1 LDX-3232 Default Settings  
GPIB mode in LOCAL via front panel, or in REMOTE via GPIB  
PARAMETERS not selected  
CAL PD = 0 µA / mW  
LIM I (high range) = 1000 mA  
LIM I (low range) = 500 mA  
LIM V = 15 volts  
LIM P = 5000 mW  
Output off  
DISPLAY enabled, in I mode  
Constant I, low bandwidth mode selected  
I setpoint = 0 mA  
I
setpoint = 0 µA  
PD  
P
setpoint = 0 mW  
PD  
RECALL BIN number = 0  
Connecting to the Laser  
When connecting your laser to the LDX-3232, we recommend that the instrument  
be powered up with the output off. In this condition, a low impedance shunt is  
active across the output terminals. When disconnecting devices, it is only  
necessary to turn the current source output off.  
It is also recommended that the connections to the LDX-3232 output be made  
using twisted wire pairs with an earth-grounded shield (see Figures 2.1 - 2.4). The  
output terminals of the instrument are left floating relative to earth ground to  
suppress AC power-on/power-off transients that may occur through an earth-  
ground path. If the output circuit is earth-grounded at some point (such as through  
the laser package and mount), the user must be careful to avoid multiple earth  
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LDX-3232  
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OPERATION  
Connecting to the Laser  
C H A P T E R  
2
grounds in the circuit. Multiple earth grounds may provide circuit paths that induce  
spurious currents in the photodiode feedback circuit and output leads.  
Note: Cable connections to the laser must be secure! Loose connections can cause  
momentary open circuits that can damage the laser.  
Figures 2.1 - 2.4 show the possible configurations of connecting laser diodes and  
photodiodes with the LDX-3232 High Compliance Laser Current Source.  
LDX-3232 Current Source  
OUTPUT  
7
+
Bias  
+
6
9
-
5
3
P. D.  
L. D.  
Earth Ground  
Figure 2.1 Common Laser Cathode - Photodiode Cathode  
LDX-3232 Current Source  
OUTPUT  
7
+
Bias  
6
9
+
-
5
3
P. D.  
L. D.  
Earth Ground  
Figure 2.2 Common Laser Cathode - Photodiode Anode  
LDX-3232 Current Source  
OUTPUT  
7
+
Bias  
+
6
9
-
5
3
P. D.  
L. D.  
Earth Ground  
Figure 2.3 Common Laser Anode - Photodiode Cathode  
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OPERATION  
Connecting to the Laser  
C H A P T E R  
2
LDX-3232 Current Source  
OUTPUT  
7
+
Bias  
6
9
+
-
5
3
P. D.  
L. D.  
Earth Ground  
Figure 2.4 Common Laser Anode - Photodiode Anode  
The 9-pin connector marked CURRENT SOURCE on the back panel is used to  
connect your laser diode to the LDX-3232. There are connections provided for  
laser cathode and anode, photodiode cathode and anode, chassis ground and  
interlock. The pinout diagram for this connector is shown in Figure 2.5.  
1, 2 Interlock  
3
4
5
6
7
8
9
Chassis Ground  
Cathode Voltage Sense  
Laser Cathode  
PDCathode (+)  
PDAnode (-)  
1
2
6
7
3
4
5
8
9
Anode Voltage Sense  
Laser Anode  
Figure 2.5 Back Panel LD Connector  
Interlock Connections  
In order for the laser output to be enabled a short circuit must exist between the  
Interlock Pins (Pins 1 and 2) of the connector. The short can be a direct short  
across the pins or a switch to prevent laser operation until the switch is closed. If a  
short does not exist between these two pins, the INTERLOCK LED will illuminate  
on the front panel and the laser output will be disabled.  
Note: The BNC Interlock Connection from the BNC connector on the rear panel will also  
make the INTERLOCK LED illuminate. Please see the notes in chapter five on use of the  
BNC interlock connection to learn more about its operation.  
The interlock terminals on the LASER connector, pins 1 and 2, must be kept isolated  
from all other connections including earth ground.  
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OPERATION  
Connecting to the Laser  
C H A P T E R  
2
Photodiode Connections  
Many laser diode modules contain an internal photodiode that monitors the back-  
facet emission of the laser. Usually, this photodiode is internally connected to  
either the laser anode or cathode.  
The photodiode and laser connections to the LDX-3232 are electrically isolated  
from ground and each other. So, if a 4 pin connection is made (no common  
connections), no additional jumpers are required. Figures 2.1 - 2.4 show the  
recommended connections and shielding for 3-pin lasers (where the common  
connection is internal to the device). A 4-pin laser should be connected with the  
same shielding as shown in Figure 2.1, but the common connection (between the  
photodiode and the laser) is optional.  
Setting the PD Bias  
The LDX-3232 provides an adjustable reverse bias of 0-5 VDC for the photodiode.  
To set the photodiode bias to 5 V reverse bias, turn the back panel PD BIAS  
ADJUST fully clockwise. To set the photodiode bias to 0 V reverse bias, turn the  
back panel PD BIAS ADJUST fully counter-clockwise.  
Grounding Considerations  
The LASER outputs of the LDX-3232 High Compliance Current Source are  
isolated from chassis ground, allowing either output terminal to be grounded at the  
user's option. Figures 2.1 - 2.4 show the proper earth-ground shielding for laser  
diode/photodiode connections.  
04_06  
LDX-3232  
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OPERATION  
Front Panel Operation  
C H A P T E R  
2
Front Panel Operation  
This section describes fundamentals of operation for your LDX-3232 in two  
operating modes: Constant Current (I) and Constant Power (P).  
The Display  
The digital display is used to show control parameters such as laser drive current  
(mA), laser current limit (mA), laser forward voltage (V), voltage limit (V), monitor  
photodiode current (µA), and laser optical power (mW) in both setpoint and  
measurement modes. It will also display error codes that relate to LASER  
operation. Error indicators underneath the display indicate control errors and are  
explained in the section titled “ERROR INDICATORS”. All laser control  
parameters are displayed on this digital display with the appropriate annunciator  
illuminated.  
Operating a Laser in Constant Current (I) Mode  
Suppose you have an LDX-3232 and you want to run the instrument in Constant  
Current, low bandwidth mode, with a setpoint of 1500 mA and a current limit of  
1750 mA. This particular mode uses a low-pass filter on the laser drive current  
output to significantly reduce noise. In this mode a modulation input of up to  
10 kHz may be used via the front panel MOD EXTERNAL connector. Follow the  
instructions below in the sequence presented.  
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OPERATION  
Operating a Laser in Constant Current (I) Mode  
C H A P T E R  
2
Setting Up the Precision Current Source  
Set the LDX-3232 in Constant Current, low bandwidth mode  
by selecting I in the MODE section of the front panel. Do this  
by toggling the SELECT push button until the I indicator is  
illuminated. Repeatedly pressing the (MODE) SELECT  
switch cycles through the current (I), light power (P), or  
high-bandwidth current (IHBW) control modes.  
Next, in the RANGE section set the current source range by  
selecting the 2000 mA range indicated by the accompanying  
LED. You will need to press the SELECT push button twice  
to change the range. It must be pressed twice quickly (within  
less than 1 second) to switch between ranges, and the  
LASER output must be off (LASER MODE ON indicator  
unlit) in order to change ranges.  
Configure the display so that it reads laser current in mA. Press and release the  
SELECT switch in the DISPLAY section of the front panel until the mA annunciator  
is lit. The (DISPLAY) SELECT switch is also used to select the IPD (PD current,  
µA), PPD (laser power, mW), or V (forward voltage, V) measurement or setpoint  
display modes. When the setpoint mode is active, the corresponding annunciator  
will flash to indicate setpoint rather than measurement display.  
To only view the setpoint, press and hold down the display SELECT switch for two  
or more seconds. When the SELECT switch is released the previous  
measurement mode will be restored.  
At this point the LDX-3232 is in Constant Current Mode, (I), in the 2000 mA range,  
and the display is reading in mA. Next, we need to adjust the setpoint of the laser  
current source.  
To adjust the setpoint of the current source to 1500 mA, turn the adjust knob to  
vary the setpoint. When the adjust knob is turned, the LDX-3232 automatically  
changes to setpoint mode indicated by the flashing annunciator. Adjust the  
setpoint to 1500 mA. After an adjustment has been made, and the adjust knob is  
released, the setpoint mode will time out in three seconds. The display will revert  
to the original measurement display mode (I, IPD, V, or PPD).  
The instrument is still not ready to turn on the laser. One of the laser protection  
features our precision current sources offer is a fully independent hardware  
current limit. The current limit protects your laser by never allowing the laser drive  
current to exceed the limit independent of the setpoint and the output control  
mode (Constant Current or Constant Power).  
04_06  
LDX-3232  
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OPERATION  
Operating a Laser in Constant Current (I) Mode  
C H A P T E R  
2
To set the current source limit, use the SELECT  
push button in the PARAMETER section of the front  
panel to select LIM I. Press and hold the  
(PARAMETER) SET push button and rotate the  
adjust knob to vary the limit setpoint value. Set the  
limit to 1750 mA. Once the (PARAMETER) SET  
push button is released, the new parameter value is  
stored in non-volatile memory.  
When the LASER current limit is reached, the CURRENT LIMIT error indicator  
flashes. The current limit setting is independent of the voltage drop of the device  
connected to the LASER output, and therefore, no dummy load is required for  
precise adjustment of the current limit. Furthermore, since the current limit  
circuitry is fully independent of the main current control, the current limit can be  
adjusted safely, even while the LASER output is active.  
An additional feature of the LDX-3232 instrument is an adjustable voltage limit.  
This allows an extra level of laser protection in the event of an intermittent open  
circuit. For maximum protection via the fastest open-circuit detection, the voltage  
limit should be set to a value slightly greater than the intended operating voltage.  
To set the LASER voltage limit, use the SELECT push  
button in the PARAMETER section of the front panel to  
select COMP V and then press and hold the (PARAMETER)  
SET push button. While holding the (PARAMETER) SET  
push button, adjust the voltage limit using the adjust knob.  
Now you are ready to enable the current source output for  
your laser diode.  
In the MODE section of the front panel, press the push button labeled OUTPUT.  
The accompanying LED labeled ON will illuminate, indicating that the laser current  
source's output is enabled. The instrument will drive the current source to the  
value set by the corresponding MODE setpoint. When the LASER output is off, an  
internal short is placed across the LASER output. The OUTPUT switch has a  
toggling action. Pressing the switch again will disable the current source output  
and the ON LED will not be illuminated. The default condition for the current  
source output is off when the instrument is first powered up. With the laser output  
enabled, the LASER display should be indicating measured laser current. If the  
output won't function, check the following conditions:  
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OPERATION  
Operating a Laser in Constant Power (P) Mode  
C H A P T E R  
2
Conditions That Will Automatically Shut Off the LASER OUTPUT  
The following conditions will automatically cause the instrument to disable the  
current source output:  
LASER High Power Limit  
LASER Interlock / Key Lock Turned Off  
LASER Open Circuit or Voltage Limit  
Operating a Laser in Constant Power (P) Mode  
Suppose you want to operate a 3 mW laser at constant 1mW level. The LDX-3232  
allows you to operate the laser current source driver in a Constant Power mode.  
In this mode, the LDX-3232 drives current to the laser to reach a setpoint power  
value (in mW). The control loop feedback parameter is photodiode current that the  
LDX-3232 converts to optical power via a user-defined photodiode responsivity  
number. If laser power changes due to internal or environmental conditions, the  
LDX-3232 will increase/decrease the current to the laser to maintain the power  
setpoint. The following paragraphs detail the instrument configuration in Constant  
Power Mode.  
To set the LDX-3232 in Constant Power mode, select P in the MODE section of  
the front panel by toggling the SELECT push button. Repeatedly pressing the  
(MODE) SELECT switch cycles through the current (I), light power (P), or high  
bandwidth current (IHBW) control modes. The LED indicator shows the selected  
mode.  
Entering Photodiode Responsivity Values  
The photodiode responsivity, CAL photodiode, is  
used to convert between photodiode current and  
optical power of the laser diode. To enter the CAL  
photodiode parameter, select CAL PD with the  
(PARAMETER) SELECT push button by toggling  
down past LIM P. The indicator becomes lit when  
CAL PD is selected and the display indicates the  
responsivity parameter in µA/mW (not an-  
nunciated). Rotate the adjust knob while holding the  
(PARAMETER) SET push button to enter a new  
value for responsivity. When the correct value is  
displayed, store the number by releasing the  
(PARAMETER) SET pushbutton.  
04_06  
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OPERATION  
Operating a Laser in Constant Power (P) Mode  
C H A P T E R  
2
A method to calculate the responsivity is suggested below.  
1
2
3
Measure (with a calibrated detector) the output power of the device.  
Measure the corresponding photodiode current.  
Calculate the responsivity by dividing the photodiode current by the optical power noting  
the units required are µA/mW.  
The LDX-3232 High Compliance Current Source can be put  
into a special mode with the CAL PD parameter set to zero.  
When the CAL PD value is zero, the LASER output will be  
controlled to the IPD setpoint value. Therefore, the  
instrument is in Constant IPD mode. The display will indicate  
"-.-" for the power measurement.  
Next, configure the display so that it reads in mW by pressing and releasing the  
(DISPLAY) SELECT switch until the mW annunciator is lit.  
Adjust the Constant Power setpoint of the LDX-3232 to 1.00 mW. To do this, turn  
the adjust knob to vary the setpoint. When the adjust knob is turned, the  
LDX-3232 automatically changes to setpoint mode as indicated by the flashing  
annunciator. Adjust the setpoint to 1.00 mW. After an adjustment has been made,  
and the adjust knob is released, the setpoint mode will time out in three seconds.  
The display will then return to the measurement display mode (I, IPD, V, or PPD).  
Before the laser output is enabled, the power limit for the laser under test should  
be set. In Constant Power mode, this is accomplished by setting a Power limit,  
LIM P value. The LDX-3232 uses the responsivity value entered to calculate a  
power limit as a function of monitor current (IPD). This is a software limit only.  
To set the Constant Power limit, use the SELECT push button in the  
PARAMETER section to select LIM P. When the LIM P is indicated by the  
accompanying LED, the display will indicate the limit setpoint in mW. Press and  
hold the (PARAMETER) SET push button and rotate the adjust knob to set the  
limit to 1.50 mW. When the desired value is reached, release the (PARAMETER)  
SET push button to store the new limit value.  
The LIM P is the absolute limit of optical power, as detected by the unit via the  
monitor photodiode feedback loop. In order for this limit to be meaningful, the  
monitor photodiode responsivity (CAL PD) must be adjusted correctly. This limit is  
a software limit only. The LASER output is normally turned off if this limit is  
reached (See LASer:ENABle:OUTOFF command in Chapter 4 for instructions on  
disabling this function). The maximum LIM P value is 5000.0 mW.  
Also, in constant power mode the LASER current limit and voltage limit values are  
in effect. Setting of these limits is described later in this chapter.  
18  
LDX-3232  
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OPERATION  
Error Indicators  
C H A P T E R  
2
Now the instrument is configured to operate in Constant  
Power Mode. In the MODE section, enable the output of the  
laser current source by depressing the OUTPUT push  
button once. The accompanying LED labeled ON will  
illuminate indicating that the laser output is on and current is  
being driven to the laser. The LDX-3232 current source will  
drive the laser to the Constant Power setpoint and maintain  
closed loop control with the photodiode current  
measurement.  
Error Indicators  
The LDX-3232 High Compliance Current Sources indicate general operational  
error conditions. Each error condition results in an action as shown in the table  
below.  
Table 2.2 LDX-3232 Error Indicators  
Error Condition  
Interlock  
Action  
Output off; INTERLOCK light flashes at 1 Hz  
Open Circuit  
Output off; OPEN CIRCUIT light flashes at 1 Hz; if this condition was caused by  
an excessively high compliance voltage, the VOLTAGE LIMIT light will also be  
turned on.  
Current Limit  
Voltage Limit  
CURRENT LIMIT light flashes at 1 Hz  
VOLTAGE LIMIT light flashes at 1 Hz; this indicator warns that the output is within  
0.25 V of LIM V setting; if the voltage limit (LIM V) is reached, the LASER output  
will shut off.  
Optical Output  
Power Limit  
Output off; POWER LIMIT light flashes at 1 Hz  
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OPERATION  
Error Indicators  
C H A P T E R  
2
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REMOTE OPERATION  
C H A P T E R  
3
C H A P T E R  
3
REMOTE OPERATION  
Everything you learned to do from the front panel can also be done remotely and  
in some cases, with more flexibility. For instance, in remote mode, you have  
access to commands for functions not found on the front panel, such as  
commands that will increment (INC) and decrement (DEC) the current setpoint by  
a pre-defined step value. The following sections show you the fundamentals of  
operating your LDX-3232 High Compliance Current Source remotely through the  
GPIB interface.  
Reading the GPIB Address  
Before you can operate the LDX-3232 instrument from a remote location, you  
need to know its GPIB address. Simply press the LOCAL switch in the section  
labeled GPIB on the front panel. The instrument will display the address. The  
default address from the factory is address "Adr 01".  
Changing the GPIB Address  
Every device on the GPIB bus must have a unique address. If it is necessary to  
change the address, press and hold in the (PARAMETER) SET switch while  
displaying the GPIB address. Turn the ADJUST knob until the desired address  
value is displayed, then release the SET switch. The new GPIB address will then  
be stored in non-volatile memory. The allowable address range is 0-30 for primary  
GPIB addressing. Extended GPIB addressing is not implemented on the  
LDX-3232 at this time.  
04_06  
LDX-3232  
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REMOTE OPERATION  
LDX-3232 Current Source Command Set  
C H A P T E R  
3
Changing Operation from Local to Remote  
Sending a command over the GPIB will automatically put the  
instrument in REMOTE mode. The REMOTE indicator will  
identify when the Current Source is in remote operation mode.  
When the instrument is in REMOTE mode, pressing the LOCAL  
switch returns the instrument to LOCAL control mode unless the  
Local Lockout state has been activated by the host computer.  
Local Lockout disables all LDX-3232 High Compliance Current  
Source front panel switches until this condition is changed by the  
host computer. When the instrument is put in Local Lockout  
Mode by the host computer, the REMOTE indicator will flash at a  
1Hz rate to indicate that the front panel is completely disabled by  
Local Lockout.  
The TALK/LISTEN indicator is illuminated when the instrument is communicating  
over the GPIB bus.  
LDX-3232 Current Source Command Set  
For the most efficient and effective remote control of your LDX-3232 High  
Compliance Current Source, we recommend you study the following sections. You  
will learn about the LDX-3232 command sets, both GPIB-IEEE488 Command  
Commands and the most used device specific commands, and command syntax.  
Later in this chapter you will be introduced to the error and status registers.  
Command Syntax  
Any command or command query must contain all of the letters that are shown in  
the LDX-3232 Command Path Structure, Figure 3.2. However, the Current  
Source's command parser is NOT CASE SENSITIVE so upper or lower case may  
be used in any combination. The lower case letters shown with the Device  
Dependent commands in Chapter 4 are optional letters and may be used for  
clarity. For example, the following commands are equal:  
LAS:DIS 1  
LAS:DisP 1  
LAS:DISPLAY 1  
In this example, only the first three letters "DIS" are required, while the other  
letters, "play" are optional. These optional letters must be used in the proper  
sequence as shown.  
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REMOTE OPERATION  
LDX-3232 Current Source Command Set  
C H A P T E R  
3
The syntax of the LDX-3232 High Compliance Current Source commands follows  
the rules laid out in the GPIB-IEEE488 standard. Colons (:) indicate the start of a  
new command path, while semicolons (;) indicate a separation of commands  
within a command string. A leading colon on a command may be used to return  
the LDX-3232 High Compliance Current Source command parser to the  
command path root (see Figure 3.1).  
Spaces or white space may be used to separate commands and/or data (after the  
command header or query question mark). Spaces or white space must be used  
to separate the command (header) from the first parameter (or program data). The  
following examples show valid syntax for commands with the LDX-3232 High  
Compliance Current Source:  
LAS:display:ldi  
Laser:limit:ldi 400  
LAS:DIS 1; las:set:ldi?  
Las:MODE:Mdp; LAS:OUT 1  
The following are examples of invalid syntax for the LDX-3232 High Compliance  
Current Source. These command strings would produce an erroneous result, as  
explained:  
LAS:MODE MDP  
LAS:MODE:ILBW DEC  
LAS:DIS ?  
Missing colon, MODE? expected  
Missing semicolon, DEC command generates an error  
Space not allowed before question mark, DIS command  
expected  
Las:LDI33;dis?  
Space missing between LDI command and the parameter  
value, 33  
For further clarity in programming, the (Boolean) values of one (1) and zero (0)  
may be used or their names as indicated in the following table:  
Table 3.1 Substitute Parameter Names  
Substitute Name  
ON  
Value  
1
0
1
0
1
0
1
0
OFF  
OLD  
NEW  
TRUE  
FALSE  
SET  
RESET  
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LDX-3232  
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REMOTE OPERATION  
LDX-3232 Current Source Command Set  
C H A P T E R  
3
If multiple parameters are expected, they should be separated with commas:  
LAS:INC 100,50  
A query has no space between the mnemonic and the question mark:  
LAS:LDI?  
The LDX-3232 High Compliance Current Source uses a terminator of  
<NL><^END> (new line with EOI). For users whose GPIB driver defaults expect a  
carriage return in the terminator, <CR><NL><^END>, the TERMcommand may be  
used for convenience (see TERMcommand in Chapter 4). For more information,  
refer to your GPIB driver configuration manual.  
The command structure is illustrated in Figure 3.1. Table 4.1 lists all of the  
LDX-3232 High Compliance Current Source’s device-dependent commands, with  
the full path shown for each command and a brief explanation of its usage.  
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REMOTE OPERATION  
C H A P T E R  
3
Command Paths  
Command Paths  
The LDX-3232 High Compliance Current Source device-dependent commands  
are structured into a tree format (see Figure 3.1). Each of the legal paths is listed  
below, followed by its list of path options, each of that is followed by the  
commands themselves. It is recommended that the first-time user begin learning  
the commands by using the full path notation. Once you are familiar with the  
commands, you may wish to take advantage of the shortcuts allowed for  
command paths.  
(root)  
(com.  
DELAY  
LAS  
cmds)  
ERR?  
*CAL?  
MES  
*CLS  
:CALMD  
:CALMD?  
:COND?  
:DEC  
:CAL  
:MODE  
:ENAB  
:LIM  
:SET  
:DIS  
MES?  
*ESE  
*ESE?  
*ESR?  
*IDN?  
*OPC  
RAD  
RAD?  
:CONST?  
:LDI  
:LDI?  
:LDI  
:COND  
:IHBW  
:ILBW  
:MDP  
:I1  
:I1?  
:I3  
:I3?  
:MDP  
:MDP?  
:V  
SECURE  
TERM  
TERM?  
TIME?  
TIMER?  
:DIS  
:MDI?  
:MDP?  
:LDI?  
:COND?  
:EVE  
:DIS?  
:EVE?  
:INC  
:LDI?  
:LDV  
:LDV  
:LDV?  
:MDI  
*OPC?  
:EVE?  
*PSC  
*PSC?  
*PUD  
*PUD?  
*RCL  
:LDV?  
:MDI  
:OUTOFF  
:OUTOFF?  
:LDI  
:MDI?  
:V?  
:LDI?  
:LDV  
:MDI?  
:MDP  
:MDP?  
:SET  
:LDV?  
*RST  
:MDI  
:SET?  
:PARAM  
*SAV  
:MDI?  
:MDLN  
:MDLN?  
:MDP  
*SRE  
*SRE?  
*STB?  
*TST?  
*WAI  
:MDP?  
:MODE?  
:OUT  
:OUT?  
:RAN  
:RAN?  
:STEP  
:STEP?  
:TOL  
:TOL?  
Figure 3.1 LDX-3232 Command Path Structure  
04_06  
LDX-3232  
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REMOTE OPERATION  
IEEE488.2 Command Commands  
C H A P T E R  
3
IEEE488.2 Command Commands  
The IEEE488.2 Common Commands and Queries are distinguished by the "*"  
that begins each mnemonic. The diagrams below show the syntax structure for  
common commands, common commands with numeric data required, and  
command command queries.  
:
COMMAND  
:
COMMAND  
*
*
:
COMMAND  
*
< Decimal  
Numeric Program  
Data>  
< w hite  
?
space>  
Common Command  
Common Command Query  
Common Command with Numeric Data  
Numeric data is required with *PSC(1=on, 0=off), *RCL(0 to 10, see front panel  
RECALL function), *SAV(1 to 10, see front panel SAVE function), *ESE(0 to 255,  
see Figure 3.2), *SRE(0 to 255, see Figure 3.2), and *PUD(used at factory only).  
A list of all of the GPIB-IEEE488 Common Commands supported by the  
LDX-3232 follows:  
*CAL?  
*ESE?  
*OPC  
*CLS  
*ESR?  
*OPC?  
*PUD  
*RST  
*SRE  
*WAI  
*ESE  
*IDN?  
*PSC  
*PSC?  
*RCL  
*PUD?  
*SAV  
*SRE?  
*TST?  
*STB?  
For more information on these commands, refer to an ANSI/IEEE 488-1987  
standards reference.  
Note: Care should be taken to set the GPIB time-out appropriately for use with the *WAI,  
DELAY, or *OPC?Commands. If the time for a response after one of these commands  
exceed the GPIB time-out period, a bus (timeout) error will occur. Usually, after this timeout  
error, the LDX-3232 Series Instrument will generate a query error (E302). This error code is  
reported via the ERR?Query.  
26  
LDX-3232  
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REMOTE OPERATION  
LDX-3232 Frequently Used Commands  
C H A P T E R  
3
LDX-3232 Frequently Used Commands  
The LDX-3232 High Compliance Current Source’s complete command set  
contains over 60 commands that allow you to operate the current source for a  
variety of applications. Within the command set, however, is a smaller subset of  
commands that will meet most of your needs. These commands are listed in  
Table 3.2.  
Table 3.2 LDX-3232 Often Used Commands  
Name  
Parameters  
Function  
ERR?  
NONE  
Returns errors generated since the last query  
Used to set the CAL PD (monitor responsivity) constant  
Used to set the current source setpoint value  
Used to return the constant current source measured value  
Used to return the measured laser voltage value  
Used to set the low range current limit  
LAS:CALMD  
LAS:LDI  
1
1
LAS:LDI?  
LAS:LDV?  
LAS:LIM:I2  
LAS:LIM:I4  
LAS:LIM:MDP  
NONE  
NONE  
1
1
1
Used to set the high range current limit  
Used to set the constant optical power (from monitor  
photodiode) limit value  
LAS:LIM:V  
1
Used to set the current source compliance voltage limit value  
(LIM V)  
LAS:MDP  
1
Used to set the constant optical power setpoint  
Returns the actual monitor photodiode power value  
Returns the mode, ILBW, IHBW, or MDP (optical power)  
Sets the mode to constant current, high bandwidth mode  
Sets the mode to constant current, low bandwidth mode  
Sets the mode to constant optical power mode  
Used to enable/disable the current source output  
Returns the current source output status  
LAS:MDP?  
NONE  
NONE  
NONE  
NONE  
NONE  
1
LAS:MODE?  
LAS:MODE:IHBW  
LAS:MODE:ILBW  
LAS:MODE:MDP  
LAS:OUT  
LAS:OUT?  
NONE  
1
LAS:RAN  
Sets the laser current output range  
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REMOTE OPERATION  
Status Reporting  
C H A P T E R  
3
Status Reporting  
This section contains information that is relevant for understanding instrument  
error and statu reporting. It also contains information regarding the use of the  
instrument status for generating interrupts for interrupt driven programs or  
subroutines. Understanding the Operation Complete definition for the instrument  
is useful for programming synchronization. The Output Off Register section also  
contains iformation on setting some of the conditions that will force the laser  
current source output off.  
The following sections describe the Event and Condition registers, Operation  
Complete Flag, Output Off registers, and Error Messages.  
Event and Condition Registers  
In addition to the required GPIB-IEEE488 status reporting structures, the  
LDX-3232 High Compliance Current Source remote interface provides Event and  
Condition Registers for LASER operations. The Event Registers are used to  
report events that occur during the operation of the LDX-3232 High Compliance  
Current Source. Events differ from conditions in that events signal an occurrence  
once, and are not reset until the Event Register is queried, the status cleared by  
the *CLScommand, or the instrument is powered off. Conditions reflect the  
current state of the device and therefore may change many times during  
operation. Querying a Condition Register does not change its contents.  
Figure 3.3 shows the status reporting scheme of the LDX-3232 High Compliance  
Current Source. Each of the registers that may be accessed by a command or  
query has the appropriate command or query written above or below the register  
representation. For example, the LASER Condition Register may be queried via  
the LASer:COND?query.  
The condition or event registers are logically ANDed with their respective enable  
registers. These bits are then logically ORed to form a summary message in the  
status byte for that particular register.  
Operation Complete Definition  
Note that Bit 0 of the Standard Event Status Register contains the status of the  
Operation Complete flag. Enabling this bit via the *ESEcommand allows the user  
to update bit 5 of the status byte. Then, if the SRE mask has bit 5 set, and the user  
issues an *OPCcommand, the SRQ (bus) signal will be generated upon  
completion of the currently processed commands. This bus signal (SRQ) may be  
used to initiate service request routines, that depend on the completion of all  
previous commands.  
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C H A P T E R  
3
Status Reporting  
For example, the user may turn the current source on (LAS:OUT 1), enable an  
SRQ on Operation Complete (set *ESE 1and *SRE 5), and have an SRQ  
handling routine in the user's software, that reads a new measurement after the  
output on state has been reached. This allows the use of the operation complete  
features of the LDX-3232, without the need for program looping or polling that can  
tie up the GPIB. Operation Complete on the LDX-3232 is defined as:  
1
2
No operations to the LASER current source hardware are pending.  
No EEPROM (non-volatile) memory write cycles are in progress.  
Standard  
Event Status Register  
*ESR?  
LASER ConditionStatusRegister  
LASer:COND?  
0 – Current Limit  
1 – Voltage Limit  
2 – N/A  
3 – Power Limit  
4 – Interlock  
15 14 13 12 11 10 9 8  
7 6 5 4 3 2 1 0  
0 - Operation Complete  
1 - Request Control  
2 - Query Error  
3 - Device-Dependendent Error  
4 - Execution Error  
5 - Command Error  
6 - User Request  
7
6
5
4
3
2
1
0
&
&
&
&
&
&
5 – N/A  
&
&
LOGICAL  
OR  
&
&
6 – Comp. Voltage Limit  
7 – Open Circuit  
8 – Output Shorted  
9 – Out of Tolerance  
10 – Output On  
11 – Ready for Calibration  
12 – N/A  
13 – N/A  
14 – N/A  
15 – N/A  
&
3
&
&
2
&
&
1
LOGICAL  
OR  
&
&
&
&
&
&
&
&
&
0
7 - Power On  
7
6
5
4
Standard  
Event Status Enable  
Register  
QUEUE  
NOT-EMPTY  
15 14 13 12 11 10 9 8  
7 6 5 4 3 2 1 0  
{
*ESE  
*ESE?  
LASER ConditionStatusEnable  
OUTPUT  
QUEUE  
LAS :ENABle:COND  
LAS :ENABle:  
LASER EventStatusRegister  
LASer:EVEnt?  
Status Byte Register  
*STB?  
0 – Current Limit  
1 – Voltage Limit  
2 – N/A  
SERVICE  
REQUEST  
GENERATION  
15 14 13 12 11 10 9 8  
7 6 5 4 3 2 1 0  
7
6
5
4
3
2
1
0
{
0 – N/A  
1 - N/A  
2 – LASER Event  
3 – LASER Cond.  
4 - Message Available  
5 - Event Status Summary  
6 - Request Service/Master Status Summary  
7 - Error Available  
3 – Power Limit  
4 – Interlock  
5 – N/A  
6 – Comp. Voltage Limit  
7 – Open Circuit  
8 – Output Shorted  
9 – Tolerance Change  
10 – Output On/Off change  
11 – New Measurement Ready  
12 – N/A  
&
&
&
&
&
&
LOGICAL  
OR  
&
&
&
3
&
&
2
&
&
1
&
&
0
LOGICAL  
OR  
&
&
&
&
7
5
4
&
{
&
&
Service Request Enable  
&
Register  
*SRE  
*SRE?  
13 – N/A  
14 – N/A  
15 14 13 12 11 10 9 8  
7 6 5 4 3 2 1 0  
QUEUE  
NOT-EMPTY  
15 – N/A  
LASER EventStatusEnable  
LAS :ENABle:EVEnt  
LAS :ENABle :  
{
ERROR  
QUEUE  
Figure 3.2 LDX-3232 Status Reporting Schematic Diagram  
Note: If the GPIB times out while waiting for a response, either set the GPIB time-our  
longer or use SRQ generated interrupts in your program. See your GPIB manual for  
time-out configuration or SRQ programming setup.  
The *OPC, *OPC?and *WAIcommands should not be used inside a calibration routine.  
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REMOTE OPERATION  
Status Reporting  
C H A P T E R  
3
Output Off Register  
The Output Off Enable Register allows you to determine that conditions and  
events in the LDX-3232 High Compliance Current Source can cause the current  
source output to be turned off. This reigster is configured in a manner similar to  
the status reporting registers. However, the register output is not reported in the  
Status Byte Register. Rather, it sets the hardware that controls the output  
switching. The events and conditions that may be set to cause the current source  
output to be turned off are shown in Figure 3.3.  
The default (factory) settings for this register are shown in Table 3.3. These  
settings are not affected by the *PSC(Power-On Status Clear) command.  
Table 3.3 LDX-3232 Series Default Settings for Output Off Registers  
0 - disabled  
1 - disabled  
2 - N/A  
8 - N/A  
9 - disabled  
10 - N/A  
11 - N/A  
12 - N/A  
13 - N/A  
14 - N/A  
15 - N/A  
3 - enabled  
4 - N/A  
5 - N/A  
6 - N/A  
7 - N/A  
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C H A P T E R  
3
Status Reporting  
r
LASER Output Off  
Register  
14  
11 10 9  
7 6 5 4 3 2 1 0  
15  
13 12  
8
&
&
&
&
&
&
&
Logical  
OR  
&
&
&
&
&
&
&
&
&
8
9
15 14 1312 11 10  
5 4  
2
7 6  
3
1 0  
LASER Output Off  
Enable Register  
Turn Output Off  
LASer:ENABle:OUTOFF <nrf>  
LASer:ENABle:OUTOFF?  
Figure 3.3 LDX-3232 Output Off Register  
0 - LASER Current Limit  
8 - N/A  
1 - LASER Voltage Limit  
9 - LASER Output Changed to be Out of Tolerance  
2 - N/A  
10 - N/A  
11 - N/A  
12 - N/A  
13 - N/A  
14 - N/A  
15 - N/A  
3 - LASER Power Limit (output on)  
4 - N/A  
5 - N/A  
6 - N/A  
7 - N/A  
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REMOTE OPERATION  
Command Timing and Completion  
C H A P T E R  
3
Command Timing and Completion  
This section describes, for each device-dependent command, whether that  
command is performed in an overlapped or sequential manner. In other words, it  
states whether the next command may begin while the current command is being  
executed, or if the next command must wait until the current command is  
completed before its execution begins. The conditions for setting the operation  
complete flag are given in the Chapter 3 section titled Operation Complete  
Definition.  
All LDX-3232 device-dependent commands are executed in an overlapped  
manner, except the DELAYcommand that is sequential. The operation complete  
flag is set after the conditions outlined in the Operation Complete Definition have  
been satisfied.  
The *WAI(common command) is an example of a sequential command that  
forces the next command to wait until the no-operation-pending flag is true. This is  
essentially the same as waiting for the OPC flag to become true, because the no-  
operations-pending flag is used to set the OPC flag (bit 0 of the Standard Event  
Status Register).  
Commands that change the status of the instrument limits or change its mode or  
current range, step value, or status enable registers will not have their OPC flag  
set until all current writing to non-volatile memory has been completed. This is  
done to ensure that the OPC flag is never set prematurely.  
Whenever there is any output (response) data in the Output Queue, bit 4 is set in  
the Status Byte Register. Whenever there is any error message in the Error  
Queue, bit 7 is set in the Status Byte Register.  
Error Messages  
In the event of a hardware error condition, error messages will be displayed on the  
display. In most cases, the error message will appear for three seconds. In some  
cases the error code display will remain until the user changes display modes. In  
the case of multiple error messages, the display may sequentially show each  
message for three seconds. In addition to the hardware errors, GPIB errors may  
be read via the ERR?query. Table 3.4 lists the numerical error ranges by function.  
Table 3.5 contains all of the error messages that may be generated. Not all of  
these messages may appear on the front panel displays. Some refer to GPIB  
activities only.  
In remote operation, the errors can be read by issuing the ERR?query. When this  
is done, all of the error messages that are resident in the error queue are returned  
32  
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REMOTE OPERATION  
C H A P T E R  
3
Error Messages  
(up to 10 may be stored). Reading the error queue via GPIB clears the error  
queue.  
Table 3.4 Error Code Classifications  
Error Code Range  
E-001 to E-099  
E-100 to E-199  
E-200 to E-299  
E-300 to E-399  
E-500 to E-599  
Area of Operation  
Internal Program Errors  
Parser Errors  
Execution Control Errors  
GPIB Errors  
LASER Control Errors  
Table 3.5 LDX-3232 Series Error Codes  
Error Code Explanation  
E-001  
E-103  
E-104  
E-105  
E-106  
E-123  
E-124  
E-126  
Memory allocation failure  
<DEFINITE LENGTH ARBITRARY BLOCK PROGRAM DATA> length too long  
<NON-DECIMAL NUMERIC PROGRAM DATA> type not defined  
<DECIMAL PROGRAM DATA> exponent not valid  
<DECIMAL PROGRAM DATA> digit expected  
Command not found  
<program mnemonic> Lookup, failed because query/command type match failed  
Too few or too many program data elements  
E-201  
E-202  
E-203  
E-205  
E-207  
E-209  
E-210  
E-211  
E-213  
E-214  
<PROGRAM DATA> value out of range  
<PROGRAM DATA> will not convert to valid type  
Security violation, command is not available without clearance  
<PROGRAM DATA> is not a Boolean value or word  
<PROGRAM DATA> will not convert to an unsigned 16-bit value  
<PROGRAM DATA> will not convert to an unsigned 32-bit value  
<PROGRAM DATA> will not convert to a floating point value  
<PROGRAM DATA> will not convert to a character value  
<PROGRAM DATA> is incorrect block data length  
<PROGRAM DATA> length exceeds maximum  
E-302  
Query error; device was addressed to talk, but GPIB controller failed to read all of the  
<RESPONSE MESSAGE>  
04_06  
LDX-3232  
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REMOTE OPERATION  
Error Messages  
C H A P T E R  
3
Error Code Explanation  
E-501  
E-503  
E-504  
E-505  
E-507  
E-510  
E-511  
E-512  
E-513  
E-515  
E-516  
E-519  
LASER interlock disabled output  
LASER open circuit disabled output  
LASER current limit disabled output  
LASER voltage limit disabled output  
LASER power limit disabled output  
LASER out of tolerance disabled output  
LASER control error disabled output  
Analog section status is all 1’s or all 0’s (power down)  
Serial EEPROM checksum error  
Laser output must be off to change ranges  
Incorrect configuration for calibration sequence to start  
Setting a measurement is only valid during the calibration phase for that measurement;  
user has tried to calibrate a measurement without first entering the required calibration  
mode.  
34  
LDX-3232  
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COMMAND REFERENCE  
C H A P T E R  
4
C H A P T E R  
4
COMMAND REFERENCE  
This chapter is a guide to all of the device-dependent commands for the  
LDX-3232 High Compliance Current Source. This chapter is divided into two  
parts. The first part contains an overview of the remote commands used by the  
LDX-3232 High Compliance Current Source. The second part contains all of the  
LDX-3232 commands in alphabetical order. Figure 4.1 shows the format for the  
device command descriptions in this chapter. The commands that emulate local  
(front panel) operation are denoted by the solid box next to the Local label in the  
upper left corner of the command description.  
Table 4.1 LDX-3232 Series Device-Dependent Commands  
Name  
Parameters  
Function  
DELAY  
1
Used to create a delay in the execution of further  
commands  
ERR?  
NONE  
1
Returns errors generated since the last query  
LAS:CALMD  
Used to set the CAL PD (monitor responsivity) constant  
Returns the CAL PD (monitor responsivity) constant  
Factory use only  
LAS:CALMD?  
LAS:CAL:CONST?  
LAS:CAL:LDI  
LAS:CAL:LDI?  
NONE  
1
NONE  
NONE  
Used to enter the laser current calibration mode  
Returns the ready state for entering the laser current  
calibration value  
LAS:CAL:LDV  
LAS:CAL:LDV?  
NONE  
NONE  
Used to enter the laser voltage calibration mode  
Returns the ready state for entering the laser voltage  
calibration mode  
LAS:CAL:MDI  
NONE  
Used to enter the monitor photodiode current calibration  
mode  
04_06  
LDX-3232  
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COMMAND REFERENCE  
C H A P T E R  
4
Name  
Parameters  
Function  
LAS:CAL:MDI?  
NONE  
Returns the ready state for entering the monitor  
photodiode current calibration value  
LAS:COND?  
LAS:DEC  
NONE  
Returns the value of the LASER condition register  
0, 1 or 2  
Used to decreate the laser current setpoint value by one  
or more steps  
LAS:DIS  
1
Turns the LASER display on or off  
LAS:DIS?  
NONE  
NONE  
NONE  
NONE  
NONE  
NONE  
Returns the LASER display value  
LAS:DIS:LDI  
LAS:DIS:LDI?  
LAS:DIS:LDV  
LAS:DIS:LDV?  
LAS:DIS:MDI  
Turn on/off LASER display to show laser output current  
Returns status of laser output current display, on/off  
Turn on/off LASER display to show laser output voltage  
Returns status of laser output voltage display, on/off  
Turn on/off LASER display to show photodiode monitor  
current  
LAS:DIS:MDI?  
LAS:DIS:MDP  
LAS:DIS:MDP?  
NONE  
NONE  
NONE  
Returns status of photo diode monitor current display,  
on/off  
Turns on/off LASER display to show photodiode monitor  
power  
Returns status of photodiode monitor power display,  
on/off  
LAS:DIS:PARAM  
LAS:DIS:SET  
NONE  
NONE  
Enables LASER display to show parameter values  
Shows the LASER display setpoint corresponding to  
mode  
LAS:DIS:SET?  
LAS:ENAB:COND  
LAS:ENAB:COND?  
LAS:ENAB:EVE  
LAS:ENAB:EVE?  
LAS:ENAB:OUTOFF  
NONE  
Returns status of LASER setpoint display, on/off  
Sets the enable register for LASER conditions  
Returns the value of the LAS conditions enable register  
Sets the enable register for LAS events  
1
NONE  
1
NONE  
1
Returns the value of the LAS event enable register  
Sets the enable register for LAS conditions, that turn the  
LAS output off  
LAS:ENAB:OUTOFF?  
LAS:EVENT?  
LAS:LDI  
NONE  
NONE  
1
Returns the value of the LAS outoff enable register  
Returns the value of the LAS event register  
Used to set the LASER constant current source setpoint  
value  
LAS:LDI?  
LAS:INC  
NONE  
Used to return the constant current source measured  
value  
0, 1, or 2  
Used to increment the LASER setpoint value by one or  
more steps  
LAS:LDV  
1
Used to set the laser voltage value for calibration  
Used to return the measured laser voltage value  
LAS:LDV?  
NONE  
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COMMAND REFERENCE  
C H A P T E R  
4
Name  
Parameters  
Function  
Used to set the LASER low range current source limit  
LAS:LIM:I2  
LAS:LIM:I2?  
LAS:LIM:I4  
LAS:LIM:I4?  
1
NONE  
1
Used to return the LASER low range current source limit  
Used to set the LASER high range current source limit  
NONE  
Used to return the LASER high range current source  
limit  
LAS:LIM:MDP  
LAS:LIM:MDP?  
1
Used to set the constant optical power (from monitor  
photodiode) limit value  
NONE  
Used to return the optical power (from monitor  
photodiode) limit value  
LAS:LIM:V  
1
Used to set the LASER compliance voltage limit value  
LAS:LIM:V?  
NONE  
Used to return the LASER compliance voltage limit  
value  
LAS:MDI  
1
Used to set the constant optical power setpoint, if  
photodiode responsivity is 0  
LAS:MDI?  
NONE  
Used to return the monitor photodiode current  
measured value  
LAS:MDLN  
1
Used to enable/disable the front panel modulation input  
LAS:MDLN?  
NONE  
Used to return the status of the front panel modulation  
input  
LAS:MDP  
1
Used to set the constant optical power setpoint  
Returns the actual monitor photodiode power value  
LAS:MDP?  
LAS:MODE?  
NONE  
NONE  
Returns the mode, I (current), IHBW (high bandwidth),  
or P (optical power)  
LAS:MODE:IHBW  
LAS:MODE:ILBW  
LAS:MODE:MDP  
LAS:OUT  
NONE  
NONE  
NONE  
1
Sets the mode to constant current, high bandwidth  
Sets the mode to constant current, low bandwidth  
Sets the mode to constant optical power mode  
Used to enable/disable the current source output  
Returns the current source output status  
Sets the laser current output range  
LAS:OUT?  
NONE  
1
LAS:RAN  
LAS:RAN?  
NONE  
NONE  
NONE  
NONE  
1
Returns the laser current output range  
LAS:SET:LDI?  
LAS:SET:MDI?  
LAS:SET:MDP?  
LAS:STEP  
Returns the laser constant I (current) setpoint  
Returns the laser constant optical power setpoint  
Returns the constant P (optical power) setpoint  
Used to set the LASER setpoint step value  
Returns the LASER setpoint step value  
LAS:STEP?  
LAS:TOL  
NONE  
2
Used to set the LASER setpoint tolerance value and  
time period value  
04_06  
LDX-3232  
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COMMAND REFERENCE  
C H A P T E R  
4
Name  
Parameters  
Function  
LAS:TOL?  
NONE  
Used to return the LASER setpoint tolerance value and  
time period value  
MES  
1
Used to enter a string message of up to 16 bits  
Returns a previously stored ASCII message  
MES?  
RAD  
NONE  
1
Sets the radix type for numerical data; decimal, binary,  
octal or hexadecimal  
RAD?  
NONE  
1
Used to return the radix type for numerical data  
Used to add a carriage return to the device terminator  
Returns the status of the TERM command  
TERM  
TERM?  
TIME?  
NONE  
NONE  
Returns the elapsed time since the instrument was last  
powered up  
TIMER?  
NONE  
Returns the elapsed time since the timer was last reset  
38  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Commands  
C H A P T E R  
4
LDX-3232 Device-Dependent Commands  
This section contains all of the device-dependent commands for the LDX-3232  
High Compliance Current Source, listed in alphabetical order. Sub-sections for  
each path are presented, listing the commands that are legal for that path. See  
Figure 3.1 for command path tree structure.  
Command Path:Name  
Required letters are shown in  
upper case; lower case letters  
are optional.  
Front Panel/  
Remote Execution  
Front Panel  
1
LASer:LIMit:I  
A solid box means the command  
can be executed in that mode.  
Command mnemonics in front  
panel (local) mode may vary.  
Remote  
The LASer:LIMit:I2 command sets the laser current  
limit value.  
Command Description  
SYNTAX DIAGRAM  
Syntax Diagram  
(For Remote Commands)  
:
LAS  
:
LIM  
Parameters  
Tells what parameters are  
expected, and their type.  
<white  
space>  
< nrf  
value >  
I2  
:
An <nrf value> refers to a  
flexible numeric notation  
(IEEE-488.2). Integer,  
An <nrf value> that represents the LASER limit  
current, in mA.  
PARAMETERS  
exponential, or floating point  
may be used with the decimal  
radix. Alternate radices may be  
selected in remote operation.  
POINTS OF  
INTEREST  
The current limit is in effect in all modes of  
operation of the laser output.  
In local operation, the limit current is entered  
by selecting the LIM I parameter, pressing and  
holding in the (PARAMETER) SET switch,  
adjusting the ADJUST knob until the desired value  
is displayed, and then releasing the SET switch.  
Points of Interest  
Has special information  
about the command.  
Examples  
Shows typical statements  
using the command.  
EXAMPLES  
"Las:Lim:I2 100" - action: the LASER current limit  
is set to 100.0 mA.  
"LAS:LIM:I4 3000" - action: the LASER current limit  
is set to 3000.0 mA.  
Figure 4.1 Command Description Format  
04_06  
LDX-3232  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
LDX-3232 Device-Dependent Command Reference  
The following pages contain a reference for the device-dependent commands of  
the LDX-3232 High Compliance Current Source. This reference contains useful  
information for both local and remote operation of the LDX-3232.  
References to the front panel labels are capitalized in the following reference  
pages (as is done throughout this manual). Therefore, a reference to the LOCAL  
switch is meant to signify the actual switch labeled LOCAL on the front panel of  
the LDX-3232.  
In some reference, parentheses are used to signify the labeled are for a particular  
switch or LED indicator on the front panel. For example, (PARAMETER) SET  
refers to the switch labeled “SET” in the PARAMETER area of the front panel.  
FRONT PANEL  
DELAY  
REMOTE  
The DELAY command causes the execution of commands to be delayed by a user-  
defined time. This command is similar to the *WAI common command, except that  
execution resumes after the specified number of miliseconds, instead of waiting for the  
Operation-Complete flag to be set.  
Syntax Diagram  
<white  
space>  
<nrf  
value>  
:
DELAY  
Parameters An <nrf value> that represents the delay time in milliseconds.  
Notes  
The Operation-Complete flag is held false until the delay period elapses, but the *OPC?  
query will not execute until the delay period has elapsed.  
This command is useful for creating delays that don't require a lot of program code and  
don't tie up the GPIB during execution.  
The delay time is approximate, with an error of about ±10%.  
Examples  
"DELAY 500" -action: Further commands and queries are not executed until about 0.5  
seconds have elapsed from the time this command is executed.  
“LAS:LDI 22;Delay 2000;LAS:LDI?” -actions: The current is set to 22.0 mA, then the  
LDX-3232 High Compliance Current Source waits for about 2.0 seconds before returning  
the measured current.  
Note: Care should be taken to set the GPIB time-out appropriately for use with the Delay  
command.  
40  
LDX-3232  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
ERRors?  
REMOTE  
The ERRors? query returns a list of command and device errors that have occurred  
since the last query. These errors are notated by a number that corresponds to the type  
of error that occurred. See Chapter 3 for information regarding error handling.  
Syntax Diagram  
:
ERR  
?
Parameters None.  
Notes  
The response data will be a list of the current errors. The errors are represented by  
numbers and are separated by commas. A response of 0 indicates that no errors were  
reported. The response data is sent as character data. Up to 10 error codes are stored  
between error queries.  
Examples  
"ERR?" -response: 0, means no errors reported.  
"Errors?" -response: 201, means that the <PROGRAM DATA> (parameter) value out of  
range error was reported since the last ERR? query.  
FRONT PANEL  
LASer:CALMD  
REMOTE  
The LASer:CALMD command sets the laser's photodiode feedback responsivity  
(the CAL PD parameter).  
Syntax Diagram  
CALMD  
CALPD  
<white  
space>  
<nrf  
value>  
:
LAS  
:
Parameters An <nrf value>, in mA/mW. The range is 0 to 1000.  
Notes  
If the parameter is set to 0, the LDX-3232 will operate in a constant IPD mode, when  
Constant P (MDP) mode is selected.  
The parameter should be set to 0 for IPD operation modes. Otherwise, the value of this  
parameter is used to convert between IPD and PPD values. The units of this parameter are  
mA/mW.  
Examples  
"LAS:CALMD 0" -action: sets the CAL PD parameter to 0. This enables the constant IPD  
mode of operation.  
"Laser:Calmd 1" -action: sets the CAL PD parameter to 1.00 mA/mW. Therefore, a  
photodiode feedback current of 1 mA will cause the PPD display to read 1 mW.  
04_06  
LDX-3232  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:CALMD?  
The LASer:CALMD? query returns the value of the laser's photodiode feedback  
responsivity (CAL PD parameter) setting.  
Syntax Diagram  
CALMD  
CALPD  
:
:
LAS  
?
Notes  
If this value is 0, the LDX-3232 will be set to operate in constant IPD mode, and the IPD  
setpoint value will be in effect. If this value is non-zero, the LDX-3232 will be set to  
operate in constant PPD mode, and the PPD setpoint value will be in effect.  
If this value is 0, the front panel P will display "-.-” and no P value can be calculated.  
PD  
PD  
Examples  
"LASER:CALMD?" -response: 0, means the LDX-3232 is set for operation in constant  
mode (if P mode is also selected).  
I
PD  
"Las:Calmd?" -response: 1.1, means the LDX-3232 is set for operation in constant P  
mode (if P mode is also selected) and the responsivity is set to 1.1 µA/mW. 1.1 µA of  
photodiode feedback current represents 1 mW of optical power.  
PD  
FRONT PANEL  
LAS:CAL:CONST?  
REMOTE  
The LAS:CAL:CONST? query returns a stored calibration value. It is intended for factory  
use only.  
42  
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LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:CAL:LDI  
The LASer:CAL:LDI command is used to enter the LASER current setpoint,  
measurement, and limit (in low bandwidth mode) calibration mode.  
Syntax Diagram  
LDI  
I
:
:
:
LAS  
CAL  
Parameters None  
Notes  
Since the limit circuit is the same for both high and low bandwidth modes, it is only  
calibrated when low bandwidth mode is selected.  
After this command is issued, the LDX-3232 High Compliance Current Source will allow  
calibration of the current setpoint, measurement, and limit (if low bandwidth mode is  
selected). This procedure is outlined in Chapter 6.  
The calibration defaults to the selected bandwidth setting. Therefore, it is necessary to  
select the desired bandwidth (I or IHBW) and turn the LASER output on before performing  
the calibration for that bandwidth.  
Calibration is performed at the current setpoint, wherever it is set. If the LASER output is  
not on, E516 is displayed.  
In remote operation, the LASer:CAL:LDI? query may be used to determine if the  
LDX-3232 High Compliance Current Source is ready for the user to enter a value.  
Examples  
"Las:CAL:LdI" -action: the LDX-3232 enters calibration mode for LASER current.  
"Las:Cal:LDI" -action: the LDX-3232 enters calibration mode for LASER current.  
04_06  
LDX-3232  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:CAL:LDI?  
The LASer:CAL:LDI? query is used to determine that the LDX-3232 is ready for a value  
to be entered during the calibration cycle of the LASer:CAL:LDI mode.  
Syntax Diagram  
LDI  
:
:
:
LAS  
CAL  
?
I
Notes  
Examples  
After this query is issued and a response of 1 is received, the LDX-3232 will be ready for  
the user to enter a current value via the LASer:LDI command (see Chapter 6).  
"LASer:CAL:LDI?" -response: 1, means the LDX-3232 is ready for the user to enter a  
current value via the LASer:LDI command.  
“LASer:Cal:LdI?” -response: 0, means the LDX-3232 is not yet ready for the user to enter  
a LASER current value  
FRONT PANEL  
LASer:CAL:LDV  
REMOTE  
The LASer:CAL:LDV command is used to enter the LASER voltage measurement  
calibration mode.  
Syntax Diagram  
:
LAS  
:
:
CAL  
LDV  
Parameters None  
Notes  
After this command is issued, the LDX-3232 will allow calibration of the laser voltage  
measurement. This procedure is outlined in Chapter 6.  
The LASer:CAL:LDV? query may be used to determine if the LDX-3232 is ready for the  
user to enter a value.  
Examples  
"Las:CAL:Ldv" -action: the LDX-3232 enters calibration mode for LASER voltage.  
"Las:Cal:LDV" -action: the LDX-3232 enters calibration mode for LASER voltage.  
44  
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LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:CAL:LDV?  
The LASer:CAL:LDV? query is used to determine that the LDX-3232 is ready for a value  
to be entered during the calibration cycle of the LASer:CAL:LDV mode.  
Syntax Diagram  
:
:
:
LAS  
CAL  
LDV  
?
Notes  
After this query is issued and a response of 1 is received, the LDX-3232 will be ready for  
the user to enter a voltage value via the LASer:LDV command (see Chapter 6).  
Examples  
"LASer:CAL:LDV?" -response: 1, means the LDX-3232 is ready for the user to enter a  
voltage value via the LASer:LDV command.  
"LASer:Cal:LdV?" -response: 0, means the LDX-3232 is not yet ready for the user to  
enter a LASER voltage value.  
FRONT PANEL  
LASer:CAL:MDI  
REMOTE  
The LASer:CAL:MDI command is used to enter the LASER photodiode current  
calibration mode.  
Syntax Diagram  
IPD  
MDI  
:
:
:
LAS  
CAL  
Parameters None  
Notes  
After this command is issued, the LDX-3232 will automatically enter the LASER  
photodiode current calibration mode. When the LDX-3232 is ready, the user should enter  
the true measured value. This procedure is outlined in Chapter 6.  
If the LASER output is not ON or if the P mode is not selected, error code E-516 will be  
generated.  
In remote operation, the LASer:CAL:MDI? query may be used to determine if the  
LDX-3232 is ready for the user to enter a value via the LASer:MDI command.  
Examples  
"Las:CAL:MDI" -action: the LDX-3232 enters the LASER photodiode current calibration  
mode.  
"LAS:Cal:MDI" -action: the LDX-3232 enters the LASER photodiode current calibration  
mode.  
04_06  
LDX-3232  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:CAL:MDI?  
The LASer:CAL:MDI? query is used to determine that the LDX-3232 is ready for a value  
to be entered during the calibration cycle of the LASer:CAL:MDI mode.  
Syntax Diagram  
MDI  
:
:
:
LAS  
CAL  
?
IPD  
Notes  
Examples  
After this query is issued and a response of 1 is received, the LDX-3232 be ready for the  
user to enter a photodiode current value via the LASer:MDI command (see Chapter 6).  
"LAS:CAL:MDI?" -response: 1, means the LDX-3232 is ready for the user to enter a  
photodiode current value via the LASer:MDI command.  
FRONT PANEL  
LASer:COND?  
REMOTE  
The LASer:COND? query returns the value of the status condition register of the LASER  
operations.  
Syntax Diagram  
:
:
LAS  
COND  
?
-where the response is the sum of the following:  
1
LASER Current Limit  
LASER Voltage Limit  
N/A  
256  
Output is shorted  
2
512  
Output is outside tolerance limit  
4
1024  
2048  
4096  
8192  
16384  
32768  
Output on/off state  
8
Power limit  
Ready for calibration data state  
16  
32  
64  
128  
Interlock disabled  
N/A  
N/A  
N/A  
N/A  
N/A  
Compliance Voltage Limit  
Open circuit  
Notes  
The LASER conditions that are reported to the status byte are set via the  
LASer:ENABle:COND command.  
The Open circuit condition is only present while the LASER output is on, and when the  
hardware detects this condition, it will turn the LASER output off. Therefore, the Open  
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C H A P T E R  
4
Circuit condition is fleeting and may be missed via the LAS:COND? query. Therefore, the  
user should test for the Open Circuit Event via the LAS:EVEnt? query.  
The LASER condition status is constantly changing, while the event status is only  
cleared when the event status is read or the *CLS command is issued.  
Examples  
"LAS:COND?" -response: 513, means that the LASER limit current and out of tolerance  
LASER conditions currently exist.  
"Radix Hex; Laser:Cond?" -response: #H108, means that the LASER Output shorted  
and Power limit conditions currently exist.  
FRONT PANEL  
LASer:DEC  
REMOTE  
The LASer:DEC command decrements the selected laser control mode setpoint by one  
or more steps. Optional parameters allow multiple steps to be decremented and the time  
(in milliseconds) between decrements to be set, respectively. This is an overlapped  
command. Other commands may be executed while this function is in progress.  
Syntax Diagram  
<white  
space>  
<nrf  
value>  
<nrf  
value>  
,
:
:
LAS  
DEC  
Parameters 0, 1, or 2. The first optional parameter is the number of steps, and the second optional  
parameter is the number of milliseconds between steps.  
Notes  
The decremental default amount is one step. The step size can be edited via the  
LAS:STEP command. LDX-3232 default values are 0.1 mA, 0.1 mW, or 1 µA  
(if CALMD = 0).  
If the first optional parameter is used, but not the second, the user may decrement the  
LASER setpoint by a multiple of the LAS:STEP size, without changing the LAS:STEP  
size.  
If the both optional parameters are used, the user may create an automated stepping  
ramp function for the LASER output.  
If the first optional parameter is entered as zero, "LAS:DEC 0", the command will do  
nothing.  
The minimum time to complete one decrement is about 20 ms. Therefore, values for the  
second optional parameter (time between decrements) have a practical minimum of 20.  
Examples  
"LAS:MODE:I; LAS:STEP 3; LAS:DEC" -action: The laser source current setpoint is  
decremented by 0.3 mA.  
"LAS:MODE:I; LAS:STEP 3; LAS:DEC 3" -action: The laser source current setpoint is  
decremented by three times the amount described in the first example.  
"LAS:MODE:I; LAS:STEP 3; LAS:DEC 3,5000" -action: The laser source current  
setpoint is decremented by the amount described in the first example, three times, with  
five seconds between decremental steps.  
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FRONT PANEL  
LASer:DISplay  
REMOTE  
The LASer:DISplay command enables or disables (turns off) the display and some LEDs  
Syntax Diagram  
<white  
space>  
<nrf  
value>  
:
:
LAS  
DIS  
Parameters An <nrf value>; -where 1 = on, 0 = off.  
Notes  
Turning the display and LEDs off means that a message of all blank spaces is sent to the  
display, and most of the LEDs will be turned off.  
Examples  
"las:dis 1" -action: turns the LASER display on and enables the LASER indicator LEDs.  
"Laser:dis Off" -action: turns the LASER display and disables the LASER indicator  
LEDs.  
FRONT PANEL  
LASer:DISplay?  
REMOTE  
The LASer:DISplay? query returns the value shown on the display.  
Syntax Diagram  
:
:
LAS  
DIS  
?
Notes  
Returns the actual (6-character) string from the output buffer to the display. If the display  
is disabled, it returns " .".  
Examples  
"LAS:DIS?" -response: "- 99.9", means the LASER display shows "- 99.9".  
"Laser:DISp?" -response: " 0.6", means the LASER display shows " 0.6".  
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C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:DISplay:LDI  
The LASer:DISplay:LDI command sets the laser display to show the constant current  
measurement.  
Syntax Diagram  
I
:
:
:
LAS  
DIS  
LDI  
Parameters None.  
Notes  
The LDI measurement display mode is turned off automatically when another display  
selection is enabled.  
Examples  
"LAS:DIS:LDI" -action: enables the display for current values.  
FRONT PANEL  
LASer:DISplay:LDI?  
REMOTE  
The LASer:DISplay:LDI? query returns the status of the LDI measurement display mode.  
Syntax Diagram  
LDI  
:
:
:
LAS  
DIS  
?
I
- where the response is 0 or 1.  
Notes  
In local operation, the status of the LDI measurement display mode is indicated by the  
enunciator next to the display (mA will be illuminated and not blinking when the display is  
in LDI measurement mode).  
Examples  
"LAS:DIS:LDI?" -response: 0, means that the LDI measurement is not displayed.  
"Las:dis:ldI?" -response: 1, means that the LDI measurement is displayed.  
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FRONT PANEL  
REMOTE  
LASer:DISplay:LDV  
The LASer:DISplay:LDV command sets the laser display to show the laser forward  
voltage measurement.  
Syntax Diagram  
V
:
:
:
LAS  
DIS  
LDV  
Parameters None  
Notes  
The LDV measurement mode is turned off automatically when another display selection  
is enabled.  
Examples  
"LAS:DIS:LDV" -action: enables the display for LDV measurement mode.  
FRONT PANEL  
LASer:DISplay:LDV?  
REMOTE  
The LASer:DISplay:LDV? query returns the status of the LDV (laser diode voltage)  
measurement display mode.  
Syntax Diagram  
LDV  
V
:
:
:
LAS  
DIS  
?
- where the response is 0 or 1.  
Notes  
In local operation, the status of the LDV measurement mode is indicated by the  
enunciator next to the display (V will be illuminated when the display is in LDV  
measurement mode).  
Examples  
"LAS:DIS:LDV?" -response: 0, means that laser voltage measurement is not displayed.  
"LAS: DIS:LDV?" -response: 1, means that the laser voltage measurement is displayed.  
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FRONT PANEL  
REMOTE  
LASer:DISplay:MDI  
The LASer:DISplay:MDI command sets the laser display to show the monitor photodiode  
current measurement.  
Syntax Diagram  
IPD  
MDI  
:
:
:
LAS  
DIS  
Parameters None  
Notes  
The MDI measurement display is turned off automatically when another display selection  
is enabled.  
Examples  
"LAS:DIS:MDI" -action: enables the display for photodiode current measurement values.  
Laser:Disp:Mdi" -action: enables the LASER display for photodiode current  
measurement values.  
FRONT PANEL  
LASer:DISplay:MDI?  
REMOTE  
The LASer:DISplay:MDI? query returns the status of the (LASER DISPLAY) IPD switch.  
Syntax Diagram  
MDI  
:
:
:
LAS  
DIS  
?
IPD  
- where the response is 0 or 1  
In local operation, the status of the MDI measurement mode is indicated by the  
Notes  
enunciator next to the display (µA will be illuminated and not blinking when the display is  
in MDI measurement mode).  
Examples  
"LAS:DIS:MDI?" -response: 0, means that the laser photodiode monitor current  
measurement is not displayed.  
"Las:dis:MDI?" -response: 1, means that the monitor photodiode current measurement  
is displayed.  
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C H A P T E R  
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FRONT PANEL  
REMOTE  
LASer:DISplay:MDP  
The LASer:DISplay:MDP command sets the display to show the monitor photodiode  
power measurement.  
Syntax Diagram  
PPD  
MDP  
:
:
:
LAS  
DIS  
Parameters None  
Notes  
The MDP measurement display is turned off automatically when another display  
selection is enabled.  
Examples  
"Las:Display:MDp" -action: enables the display for photodiode power measurement  
values.  
"Laser:Disp:MDP" -action: enables the display for photodiode power measurement  
values.  
FRONT PANEL  
LASer:DISplay:MDP?  
REMOTE  
The LASer:DISplay:MDP? query returns the status of the MDP (monitor diode power)  
measurement display mode.  
Syntax Diagram  
MDP  
PPD  
:
:
:
LAS  
DIS  
?
- where the response is 0 or 1.  
Notes  
In local operation, the status of the MDP measurement mode is indicated by the  
enunciator next to the display (mW will be illuminated and not blinking when the display  
is in MDP measurement mode).  
Examples  
"LAS:DISp:MDp?" -response: 0, means that the MDP measurement is not displayed.  
"Las:dis:MDP?" -response: 1, means that the MDP measurement is displayed.  
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FRONT PANEL  
REMOTE  
LASer:DISplay:PARAM  
The LASer:DISplay:PARAM command enables the display to show the parameter  
values.  
Syntax Diagram  
:
:
:
LAS  
DIS  
PARAM  
Parameters None  
Notes  
This command has the same effect as pressing the (PARAMETER) SELECT switch  
while in LASER mode. The selected parameter will be displayed for three seconds. The  
actual LASER PARAM display is turned off automatically when a display selection is  
enabled.  
Each time the command is issued, the next LASER parameter will be selected, see  
Chapter 2 for more information.  
Examples  
"Laser:Display:Param" -action: selects a parameter and displays its value.  
"LAS:DIS:PARAM" -action: selects a parameter and displays its value.  
FRONT PANEL  
LASer:DISplay:SET  
REMOTE  
The LASer:DISplay:SET command sets the display to show the setpoint of the selected  
display mode.  
Syntax Diagram  
:
:
:
LAS  
DIS  
SET  
Parameters None  
Notes  
Using this command has the same effect as physically holding the (DISPLAY) SELECT  
switch down continuously.  
Examples  
"Las:Dis:Set" -action: enables the display for the setpoint of the selected mode: LDI,  
MDI (IPD) or MDP (PPD)  
"LAS:Dis:Set" -action: enables the display for the setpoint of the selected display mode.  
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FRONT PANEL  
LASer:DISplay:SET?  
REMOTE  
The LASer:DISplay:SET? query returns the status of the setpoint display mode.  
Syntax Diagram  
:
:
:
LAS  
DIS  
SET  
?
- where the response is 0 or 1.  
Notes  
Examples  
The setpoint display will not time out when REMOTE operation is used. (It will be  
continuously displayed.)  
"LAS:DISPLAY:SET?" -response: 0, means the setpoint is not shown on the display.  
"Las:Dis:Set?" -response: 1, means the setpoint value is shown on the display.  
FRONT PANEL  
LASer:ENABle:COND  
REMOTE  
The LASer:ENABle:COND command sets the condition status enable register of the  
LASER operations for summary (in bit 3 of the status byte) and generation of service  
requests.  
Syntax Diagram  
<nrf  
value>  
<white  
space>  
:
:
ENAB  
COND  
:
LAS  
Parameters An <nrf value> whose sum represents the enabled bits:  
1
LASER Current Limit  
LASER Voltage Limit  
N/A  
256  
Output is shorted  
2
512  
Output is outside tolerance limit  
4
1024  
2048  
4096  
8192  
16384  
32768  
Output on/off state  
8
Power limit  
Ready for calibration data state  
16  
32  
64  
128  
Interlock disabled  
N/A  
N/A  
N/A  
N/A  
N/A  
Compliance Voltage Limit  
Open circuit  
Notes  
The enabled or disabled LASER conditions can be read by using the  
LASer:ENABle:COND? query.  
The LASER condition status can be monitored by the LASer:COND? query. If any of the  
enabled LASER conditions are true, bit 3 of the status byte register will be set.  
The enable registers normally retain their values at power-up (as they were at power-  
down) unless the power-on status clear flag is set true (for more information see the  
*PSC definition, in the GPIB-IEEE488 specification).  
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Examples  
"LAS:ENAB:COND 129" -action: enables the LASER status condition register so that the  
Open circuit and LASER current limit conditions will be summarized in the status byte  
(bit 3).  
Laser:Enable:Cond #H0F9B" - action: enables the LASER status condition register so  
that any and all of the above conditions will be reported in the status byte register (bit 3).  
FRONT PANEL  
LASer:ENABle:COND?  
REMOTE  
The LASer:ENABle:COND? query returns the value of the status condition enable  
register of the LASER operations.  
Syntax Diagram  
:
:
:
LAS  
ENAB  
COND  
?
- where the response is the sum of the following:  
1
LASER Current Limit  
LASER Voltage Limit  
N/A  
256  
Output is shorted  
2
512  
Output changed to be in/out of tolerance  
4
1024  
2048  
4096  
8192  
16384  
32768  
Output on/off state  
8
Power limit  
Ready for calibration data state  
16  
32  
64  
128  
Interlock disabled  
N/A  
N/A  
N/A  
N/A  
N/A  
Compliance Voltage Limit  
Open circuit  
Notes  
The enabled LASER conditions can be set by using the LASer:ENABle:COND  
command.  
The LASER condition status can be monitored by the LASer:COND? query.  
Examples  
"LAS:ENAB:COND?" -response: 17, means that the Laser Current Limit and Interlock  
disabled LASER conditions will be reported (in summarized form) to the status byte  
(bit 3).  
"Radix Hex; Laser:Enable:Cond?" -response: #H0F9B, means that all of the above  
conditions will be reported (in summarized form) to the status byte (bit 3).  
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FRONT PANEL  
LASer:ENABle:EVEnt  
REMOTE  
The LASer:ENABle:EVEnt command sets the status event enable register of the LASER  
operations. These events are summarized in bit 2 of the status byte register.  
Syntax Diagram  
<nrf  
value>  
<white  
space>  
:
:
ENAB  
:
EVE  
LAS  
Parameters An <nrf value> whose sum represents the bits that are enabled:  
1
LASER Current Limit  
LASER Voltage Limit  
N/A  
256  
Output is shorted  
2
512  
Output changed to be in/out of tolerance  
4
1024  
2048  
4096  
8192  
16384  
32768  
Output on/off state changed  
8
Power limit  
New measurements taken  
16  
32  
64  
128  
Interlock changed state  
N/A  
N/A  
N/A  
N/A  
N/A  
Compliance Voltage Limit  
Open circuit  
Notes  
The enabled LASER events can be read by using the LASer:ENABle:EVEnt? query. The  
LASER event status can be monitored by the LASer:EVEnt? query.  
The enable registers normally retain their values at power-up (as they were at power-  
down) unless the power-on status clear flag is set true (for more information see the  
*PSC definition, in the GPIB-IEEE488 specification).  
Examples  
"LAS:ENAB:EVENT 136" -action: enables the LASER status event register so that the  
Open circuit and Power limit events will be reported (in summarized form) to the status  
byte (bit 2).  
"Laser:Enable:Event #H0F9B" -action: enables the LASER status event register so all of  
the above events will be reported (in summarized form) to the status byte (bit 2).  
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FRONT PANEL  
REMOTE  
LASer:ENABle:EVEnt?  
The LASer:ENABle:EVEnt? query returns the value of the status event enable register of  
the LASER operations.  
Syntax Diagram  
:
:
:
LAS  
ENAB  
EVE  
?
- where the response is the sum of the following:  
1
LASER Current Limit  
LASER Voltage Limit  
N/A  
256  
Output is shorted  
2
512  
Output changed to be in/out of tolerance  
4
1024  
2048  
4096  
8192  
16384  
32768  
Output on/off state  
8
Power limit  
New measurements taken  
16  
32  
64  
128  
Interlock state changed  
N/A  
N/A  
N/A  
N/A  
N/A  
Compliance Voltage Limit  
Open circuit  
Notes  
Examples  
The enabled LASER events can be set by using the LASer:ENABle:EVEnt command.  
The LASER event status can be monitored by the LASer:EVEnt? query.  
"LAS:ENAB:EVE?" -response: 1040, means that the Output on/off state change and  
Interlock changed LASER events will be reported (in summarized form) to the status byte  
register (bit 2).  
"Radix Hex; Las:Enab:Eve?" -response: #HFDB, means that all of the above events will  
be reported (in summarized form) to the status byte register (bit 2).  
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FRONT PANEL  
LASer:ENABle:OUTOFF  
REMOTE  
The LASer:ENABle:OUTOFF command sets the status outoff enable register of the  
LASER operations (things that will turn the LASER output off).  
Syntax Diagram  
<nrf  
value>  
<white  
space>  
:
:
ENAB  
OUTOFF  
:
LAS  
Parameters An <nrf value> whose sum represents the enabled bits:  
1
LASER Current Limit  
256  
N/A  
2
LASER Voltage Limit  
512  
Output is out of tolerance*  
4
N/A  
1024  
2048  
4096  
8192  
16384  
32768  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
8
Power limit (with output on)  
16  
32  
64  
128  
N/A  
N/A  
N/A  
N/A  
Notes  
The enabled LASER outoff bits can be read by using the LASer:ENABle:OUTOFF?  
query.  
The enable registers normally retain their values at power-up (as they were at power-  
down) unless the power-on status clear flag is set true (for more information see the  
*PSC definition, in the GPIB-IEEE488 specification).  
The factory default value for this register is #B0000100000001000, #H808, or 2056  
decimal.  
Examples  
"LAS:ENAB:OUTOFF 9" -action: enables the LASER status outoff register so that Power  
limit and LASER current limit conditions will cause the LASER output to be turned off.  
"Las:Enab:Outoff #HE0B" -action: enables the LASER status outoff register so that any  
or all of the above conditions will cause the LASER output to be turned off.  
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.
FRONT PANEL  
REMOTE  
LASer:ENABle:OUTOFF?  
The LASer:ENABle:OUTOFF? query returns the value of the status outoff enable register  
of the LASER operations.  
Syntax Diagram  
:
:
:
LAS  
ENAB  
OUTOFF  
?
-where the response is the sum of the following:  
1
LASER Current Limit  
256  
N/A  
2
LASER Voltage Limit  
512  
Output if out of tolerance  
4
N/A  
1024  
2048  
4096  
8192  
16384  
32768  
N/A  
N/A  
N/A  
N/A  
N/A  
N/A  
8
Power limit (with output on)  
16  
32  
64  
128  
N/A  
N/A  
N/A  
N/A  
Notes  
Examples  
The enabled LASER events can be set by using the LASer:ENABle:OUTOFF command.  
The LASER output status can be monitored by the LASer:EVEnt? query.  
"LAS:ENAB:OUTOFF?" -response: 1, means that Current Limit Condition will cause the  
LASER output to be turned off.  
"Radix Hex; Las:Enab:Eve?" -response: #H20B, means that all of the above conditions  
will cause the LASER output to be turned off.  
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FRONT PANEL  
LASer:EVEnt?  
REMOTE  
The LASer:EVEnt? query returns the value of the status event register of the LASER  
operations.  
Syntax Diagram  
:
:
LAS  
EVE  
?
-where the response is the sum of the following:  
1
LASER Current Limit  
LASER Voltage Limit  
N/A  
256  
Output is shorted  
2
512  
Output changed to be in/out of tolerance  
4
1024  
2048  
4096  
8192  
16384  
32768  
Output on/off state changed  
8
Power limit  
Measurement ready  
16  
32  
64  
128  
Interlock disabled  
N/A  
N/A  
N/A  
N/A  
N/A  
Compliance Voltage Limit  
Open circuit  
Notes  
The LASER conditions that are reported in the status byte can be set by using the  
LASer:ENABle:EVEnt command.  
The LASER event status is only cleared when the event status is read or by the *CLS  
command while the condition status is constantly changing.  
Examples  
"LAS:EVE?" -response: 513, means that the LASER output tolerance changed and  
current limit events have occurred since the last LASer:EVEnt? query.  
"Radix Hex; Laser:Event?" -response: #H88, means that the LASER Power limit and  
Open circuit events have occurred since the last LASer:EVEnt? query.  
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FRONT PANEL  
REMOTE  
LASer:INC  
The LASer:INC command increments the selected laser control mode setpoint by one or  
more steps. Optional parameters allow multiple steps to be incremented and the time (in  
ms) between increments to be set, respectively. This is an overlapped command. Other  
commands may be executed while this function is in progress.  
Syntax Diagram  
<white  
space>  
<nrf  
value>  
<nrf  
value>  
,
:
:
LAS  
INC  
Parameters 0, 1, or 2. The first optional parameter is the number of steps, and the second optional  
parameter is the number of ms between steps.  
Notes  
The decremental default amount is one step. The step size can be edited via the  
LAS:STEP command. LDX-3232 default values are 0.1 mA, 0.1 mW, or 1 µA.  
If the first optional parameter is used, but not the second, the LASER setpoint is  
incremented by a multiple of the LAS:STEP size without changing the LAS:STEP size.  
The second optional parameter is the time, in ms, between steps.  
If both optional parameters are used, the user may create an automated stepping ramp  
function for the LASER output.  
If the first optional parameter is entered as zero, “LAS:INC 0”, the command will do  
nothing.  
The minimum time to complete one increment is about 20 ms. Therefore, values for the  
second optional parameter (time between increments) have a practical minimum of 20.  
This command should not be overlapped with “LAS:DEC” or other “LAS:INC” commands.  
Examples  
“LAS:MODE:I; LAS:STEP 3; LAS:INC” -action: The laser source current setpoint is  
incremented by 0.03 mA.  
“LAS:MODE:I; LAS:STEP 3; LAS:INC 3” -action: The laser source current setpoint is  
incremented by three times the amount described in the first example.  
“LAS:MODE:I; LAS:STEP 3; LAS:INC 3,5000” -action: The laser source current setpoint  
is incremented by the amount described in the first example, three times, with  
fiveseconds between incremental steps.  
“LAS:STEP 1; LAS:Mode:P; Las:INC” -action: The power setpoint is incremented by  
0.01 mW.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:LDI  
The LASer:LDI command sets the laser control current.  
Syntax Diagram  
I
<white  
space>  
<nrf  
value>  
:
LAS  
:
LDI  
Parameters An <nrf value> that represents the (laser) output current in mA.  
Notes  
setpoint is the same for both low and high bandwidth output modes.  
"Las:LDI 400" -action: sets the laser output current to 400.00 mA.  
"LAS:ldi 100" -action: sets the laser output current to 100.0 mA.  
Examples  
FRONT PANEL  
REMOTE  
LASer:LDI?  
The LASer:LDI? query returns the value of the measured laser current.  
Syntax Diagram  
I
:
:
LAS  
?
LDI  
- where the response is the most recent laser current measurement.  
Notes  
Response is the measured laser output current for either low or high bandwidth modes.  
This measurement is updated approximately once every 600 ms.  
Examples  
"LAS:ldi?" -response: 30.0, means the measured laser output current is 30.0 mA.  
"Laser:LDI?" -response: 100.0, means the measured laser output current is 100.0 mA.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:LDV  
The LASer:LDV command sets the laser voltage for calibration of the laser voltage  
measurement.  
Syntax Diagram  
<white  
space>  
<nrf  
value>  
:
:
LAS  
LDV  
Parameters An <nrf value> that represents the (laser) output voltage, in volts.  
Notes  
setpoint is the same for both low and high bandwidth output modes and is entered only  
for LDV calibration.  
Examples  
"Las:LDV 4" -action: enters a value of 4.000 V.  
"LAS:ldv 1.025" -action: enters a value of 1.025 V.  
FRONT PANEL  
LASer:LDV?  
REMOTE  
The LASer:LDV? query returns the value of the measured laser voltage.  
Syntax Diagram  
:
:
LAS  
LDV  
?
- where the response is the measured laser output voltage for either low or high  
bandwidth modes.  
Notes  
This measurement is updated approximately once every 600 ms.  
Examples  
"LAS:ldv?" -response: 3.03, means the measured laser output voltage is 3.03 V.  
"Laser:LDV?" -response: 1.0, means the measured laser output voltage is 1.000 V.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:LIMit:I2  
The LASer:LIMit:I2 command sets the LASER current limit value for the 2000 mA range  
on the LDX-3232.  
Syntax Diagram  
<nrf  
value>  
<white  
space>  
:
:
LIM  
I2  
:
LAS  
Parameters An <nrf value> that represents the LASER limit current, in mA.  
Notes  
The current limit is in effect in all modes of operation (ILBW, IHBW, or P). The current  
limit in use depends on the LASER output range selection.  
Examples  
"LAS:LIM:I2 180" -action: the LASER current limit is set to 180 mA.  
":Laser:Limit:I2 160" -action: the LASER current limit is set to 160 mA.  
FRONT PANEL  
LASer:LIMit:I2?  
REMOTE  
The LASer:LIMit:I2? query returns the value of the LASER current limit for the 2000 mA  
range on the LDX-3232.  
Syntax Diagram  
:
:
:
LAS  
LIM  
I2  
?
- where the response is the current limit value for the 2000 mA range.  
Notes  
The current limit is in effect in all modes of operation (ILBW, IHBW, or P). The current  
limit in use depends on the LASER output range selection.  
Examples  
"LAS:LIM:I2?" -response: 40, means the laser current limit is 40 mA.  
"Laser:LIM:I2?" -response: 50, means the laser current limit is 50 mA .  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:LIMit:I4  
The LASer:LIMit:I4 command sets the LASER current limit value for the 4000 mA range  
on the LDX-3232.  
Syntax Diagram  
<nrf  
value>  
<white  
space>  
:
:
LIM  
:
I4  
LAS  
Parameters An <nrf value> that represents the LASER limit current, in mA.  
Notes  
The current limit is in effect in all modes of operation (ILBW, IHBW, or P). The current  
limit in use depends on the LASER output range selection.  
In local operation, the limit current is entered by selecting LIM I parameter, pressing and  
holding in the (PARAMETER) SET switch, adjusting the knob until the desired value is  
displayed, and then releasing the SET switch.  
Examples  
"LAS:LIM:I4 1800" -action: the LASER current limit is set to 1800 mA.  
":Laser:Limit:I4 160" -action: the LASER current limit is set to 160 mA.  
FRONT PANEL  
LASer:LIMit:I4?  
REMOTE  
The LASer:LIMit:I4? query returns the value of the LASER current limit for the 4000 mA  
on the LDX-3232.  
Syntax Diagram  
:
:
:
LAS  
LIM  
I4  
?
- where the response is the current limit value for the 4000 mA range.  
Notes  
The current limit is in effect in all modes of operation (ILBW, IHBW, or P). The current  
limit in use depends on the LASER output range selection.  
Examples  
"LAS:LIM:I4?" -response: 400, means the laser current limit is 400 mA.  
"Laser:LIM:I4?" -response: 1500, means the laser current limit is 1500 mA.  
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LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
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REMOTE  
LASer:LIMit:MDP  
The LASer:LIMit:MDP command sets the laser monitor photodiode power limit value.  
Syntax Diagram  
MDP  
P
<nrf  
value>  
<white  
space>  
:
:
:
LAS  
LIM  
Parameters An <nrf value> that represents the laser monitor photodiode power limit in mW.  
Notes  
When constant MDP mode is used, the output level is limited only by the LIM Ix value.  
Exceeding the powere limit will either cause the output to shut off (default) or generate a  
warning (see LAS:ENAB:OUTOFF command).  
Examples  
"LAS:LIM:MDP 10" -action: sets the laser output power limit to a value that corresponds  
to producing 10.00 mW of photodiode feedback (optical) power.  
"Las:Limit:MDp 5" -action: sets the laser output power limit to a value that corresponds to  
producing 5.00 mW of photodiode feedback (optical) power.  
FRONT PANEL  
LASer:LIMit:MDP?  
REMOTE  
The LASer:LIMit:MDP? query returns the value of the laser monitor photodiode power  
limit.  
Syntax Diagram  
MDP  
P
:
:
:
LAS  
LIM  
?
- where the response is the LASER power limit setting.  
Notes  
The (LASER) MDP limit is in effect for both laser output current ranges.  
The MDP limit is not in effect when CALMD=0. In this case, the monitor current  
measurement is not converted to power.  
Examples  
"LAS:LIM:MDP?" -response: 3.0, means the monitor photodiode power limit is set to  
3.0 mW.  
":LAS:Limit:MDP?" -response: 10.0, means the monitor photodiode power limit is set to  
10.0 mW.  
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LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:LIMit:V  
The LASer:LIMit:V command sets the LASER compliance voltage limit value.  
Syntax Diagram  
<nrf  
value>  
<white  
space>  
:
:
LIM  
V
:
LAS  
Parameters An <nrf value> that represents the LASER limit voltage, in volts.  
Notes  
The voltage limit setting is useful for laser protection. When the maximum operating  
voltage of a laser is known, the user may set the voltage limit to a value slightly higher  
than the maximum operating voltage. Then, if the laser is accidentally disconnected, the  
current source will quickly sense the over-voltage and shut off.  
In local operation, the voltage limit is entered by selecting the COMP V parameter,  
pressing and holding in the (PARAMETER) SET switch. Turn the adjust knob until the  
desired value is displayed and then release the SET switch.  
Examples  
"LAS:LIM:V 5.0" -action: the LASER compliance voltage limit is set to 5.0 V.  
":Laser:Limit:V 4.60" -action: the LASER compliance voltage limit is set to 4.6 V.  
FRONT PANEL  
LASer:LIMit:V?  
REMOTE  
The LASer:LIMit:V? query returns the value of the LASER compliance voltage limit  
setting.  
Syntax Diagram  
:
:
:
LAS  
LIM  
V
?
- where the response is the LASER limit voltage setpoint.  
The voltage limit is valid for all modes of Laser operation.  
Notes  
In local operation, the voltage limit is seen by selecting the COMP V parameter, pressing  
and holding in the (PARAMETER) SELECT switch.  
Examples  
"LAS:LIM:V?" -response: 4.5, means the laser compliance voltage limit is 4.5 V.  
"Laser:LIM:V?" -response: 10.0, means the laser compliance voltage limit is set to  
10.0 V.  
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LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:MDI  
The LASer:MDI command sets the value of the optical power setpoint, in µA, if the  
CALMD (CAL PD) responsivity is 0.  
Syntax Diagram  
MDI  
IPD  
<white  
space>  
<nrf  
value>  
:
LAS  
:
Parameters An <nrf value> that represents the photodiode feedback current, in µA.  
Notes  
If the CALMD (CAL PD) parameter is not set to 0, the LAS:MDI value will not be used. In  
this case, the measured MDI would be converted to MDP (PPD, by the CAL PD factor),  
and the MDP (PPD) setpoint would be used.  
Examples  
"Las:Mdi 40" -action: The LASER output is controlled so that the photodiode feedback  
current remains constant at 40 µA.  
"Laser:MDI 200" -action: The LASER output is controlled so that the photodiode  
feedback current remains constant at 200 µA.  
FRONT PANEL  
LASer:MDI?  
REMOTE  
The LASer:MDI? query returns the value of the laser photodetector current measurement  
in µA.  
Syntax Diagram  
MDI  
IPD  
:
:
LAS  
?
- where the response is the most recent LASER monitor current measurement.  
Notes  
The response is in µA. The response is valid, even when the unit is not in constant P  
mode.  
This measurement is updated approximately once every 600 ms.  
Examples  
"Las:Mode:MDP; Las:Calmd 0; Las:MDi?" -response: 100.0, means 100 µA of  
photodetector current. This feedback is controlling the laser current output.  
"LAS:MODE:IHBW; LAS:MDI?" -response: 20.0, means 20 µA of photodetector current,  
but photodiode monitor current is not controlling the laser output current.  
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LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:MDLN  
The LASer:MDLN command enables or disables (turns off) the front panel modulation  
input (BNC).  
Syntax Diagram  
<white  
space>  
<nrf  
value>  
:
LAS  
:
MDLN  
Parameters An <nrf value> - where 1=on, 0=off.  
Notes  
After turning the modulation off, it will remain off until turned back on via this command or  
by resetting the instrument.  
Examples  
“las:mdln 1” -action: turns the modulation input on and enables modulation via the front  
panel BNC connector.  
“Laser:mdln 0” -action: turns the modulation input off. Modulation signals at the front  
panel BNC will not effect the LAS output.  
FRONT PANEL  
LASer:MDLN?  
REMOTE  
The LASer:MDLN? query returns that status of the LAS modulation control. When  
disabled, a modulation signal at the front panel BNC will not effect the LAS output.  
Syntax Diagram  
:
LAS  
:
MDLN  
?
- where the response of 1=on, 0=off.  
Notes  
The LASER modulation control switches the front panel BNC in and out of the LAS  
control circuit. At power up or after reset, modulation is enabled by default.  
Examples  
“LAS:MDLN?” -response: 1, means that the LAS modulation input is enabled.  
“las:mdln?” -response: 0, means that the LAS modulation input is disabled.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:MDP  
The LASer:MDP command sets the value of the optical power setpoint in mW if the  
CALMD (CAL PD) responsivity is greater than 0.  
Syntax Diagram  
MDP  
P
<white  
space>  
<nrf  
value>  
:
LAS  
:
Parameters An <nrf value> that represents the photodiode feedback power in mW.  
Notes  
If the CALMD (CAL PD) parameter is set to 0, the LAS:MDP value will not be used. In  
this case, the measured MDP would be invalid, and the MDI (IPD) setpoint would be used.  
Examples  
"Las:Mdp 40" -action: The LASER output is controlled so that the photodiode feedback  
power remains constant at 40 mW.  
"Laser:MDP 200" -action: The LASER output is controlled so that the photodiode  
feedback power remains constant at 200 mW.  
FRONT PANEL  
LASer:MDP?  
REMOTE  
The LASer:MDP? query returns the value of the laser photodetector power measurement  
in mW.  
MDP  
:
:
LAS  
?
P
- where the response is the most recent LASER power measurement.  
Notes  
The response is in mW. The response is valid, even when the unit is not in constant P  
mode. This measurement is updated approximately once every 600 ms.  
Examples  
"Las:Mode:MDP; Las:Calmd 460; Las:MDp?" -response: 100.0, means 100 mW of  
photodetector power. This feedback is controlling the laser current output.  
"LAS:MODE:IHBW; LAS:MDP?" -response: 20.0, means 20 mW of photodetector  
power, but photodiode monitor current is not controlling the laser output current.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:MODE?  
The LASer:MODE? query returns the selected laser control mode.  
:
:
LAS  
MODE  
?
Notes  
IHBW mode is the same as I mode (low bandwidth), except that the output low bandpass  
filter is disabled in IHBW mode.  
Examples  
"LAS:MODE?" -response: ILBW, means that constant I (current) mode is in effect for the  
laser output.  
":Las:Mode?" -response: MDP, means that constant P (power) mode is in effect for the  
laser output, and CALMD>0.  
"Las:Mode?" -response: MDI, means that constant P (power) mode is in effect for the  
laser output, and CALMD=0.  
"Laser:MODE?" -response: IHBW, means that constant IHBW (current, high bandwidth)  
mode is in effect for the laser output.  
FRONT PANEL  
LASer:MODE:IHBW  
REMOTE  
The LASer:MODE:IHBW command selects laser high bandwidth constant current mode.  
:
:
:
LAS  
MODE  
IHBW  
Parameters None  
Notes  
This mode of operation is constant I mode with the output lowpass filter disabled.  
"LAS:Mode:Ihbw" -action: enables the laser high bandwidth constant current mode.  
Examples  
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LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:MODE:ILBW  
The LASer:MODE:ILBW command selects laser constant current mode.  
I
:
:
:
LAS  
MODE  
ILBW  
Parameters None  
Notes  
Examples  
Constant I mode (low bandwidth) enables the output low bandpass filter.  
"LAS:MODE:ILBW" -action: sets the laser output for constant I mode (low bandwidth).  
FRONT PANEL  
LASer:MODE:MDP  
REMOTE  
The LASer:MODE:MDP command selects laser constant power mode.  
P
:
:
:
LAS  
MODE  
MDP  
Parameters None  
Notes  
This mode of laser operation requires the laser's monitor photodiode feedback to  
maintain constant optical power or constant monitor current.  
In this mode, the displayed parameter will be either IPD (if CALMD=0) in µA, or PPD (if  
CALMD>0) in mW.  
Examples  
"LAS:MODE:MDP" -action: sets the laser output mode of operation to constant optical  
power mode.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:OUTput  
The LASer:OUTput command turns the laser output on or off.  
<white  
space>  
<nrf  
value>  
:
:
LAS  
OUT  
Parameters An <nrf value>; 1=on, 0=off.  
Notes  
There is a two-second delay after the output is turned on before the output shorting relay  
is opened. Following this, the output current ramps up to the current setpoint slowly to  
protect the laser. Therefore, the time to turn the output on and reach the setpoint current  
varies from two to about three seconds.  
After the output is turned on, it may be useful to wait until the output is stable (within  
tolerance) before performing further operations, but it is not necessary. When the LASER  
output is off, it is safe to connect or disconnect devices to the LASER output terminals.  
When the LASER output is off, an internal short is placed across the output terminals.  
Examples  
"LAS:I 20; LAS:OUT ON" -action: sets the laser output current to 20 mA and then turns  
the output on.  
FRONT PANEL  
LASer:OUTput?  
REMOTE  
The LASer:OUTput? query returns the status of the laser output switch.  
:
:
LAS  
OUT  
?
- where the response is 0 or 1  
Notes  
Although the status of the switch is on, the output may not have reached the setpoint  
value.  
Examples  
"Las:OUT?" -response: 0, means that the output switch is disabled, devices may be  
safely disconnected or connected at the LASER output terminals.  
"LAS:OUT?" -response: 1, means that the LASER output switch is enabled, LASER  
output is present.  
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LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:RANge  
The LASer:RANge command selects the laser's drive current output range.  
<white  
space>  
<nrf  
value>  
:
:
LAS  
RAN  
Parameters An <nrf value> that represents the laser current output range.  
2 = 2000 mA, and 4= 4000 mA range  
Notes  
This range setting effects the Laser Drive Current output current range only. The Laser  
Drive Current output should be “off” when this command is issued. If the Laser Diode  
Current output is “on” when this command is issued, the LDX-3232 will generate error  
E515, and the range will not be changed.  
Examples  
"LAS:RAN 4" -action: sets the laser output drive current range to 4000 mA.  
"Laser:range 2" -action: sets the laser output drive current range to 2000 mA.  
FRONT PANEL  
LASer:RANge?  
REMOTE  
The LASer:RANge? query returns the value of the Laser Drive Current range.  
:
:
LAS  
RAN  
?
- where the response is in integer; 2 means 2000 mA range and 4 means 4000 mA  
range.  
Notes  
The resolution and accuracy of the laser limit current are dependent on the Laser Drive  
Current output range.  
Examples  
"LAS:RAN?" -response: 2, means that the Laser Drive Current range is 2000mA.  
"LAS:range?" -response: 4, means that the Laser Drive Current range is 4000mA.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:SET:LDI?  
The LASer:SET:LDI? query returns the constant I value that is used for both output  
ranges and both bandwidths.  
:
:
:
LAS  
SET  
I
LDI  
?
- where the response is the constant I setpoint value, in mA.  
In local operation, the constant I setpoint is read by selecting I or I  
Notes  
mode, then  
HBW  
pressing and holding down the SELECT switch in the DISPLAY area of the front panel.  
When the mA indicator is blinking, the display will show the LDI setpoint.  
Examples  
"LAS:SET:LDI?" -response: 50.0, means the laser output current setpoint value is  
50.0 mA.  
"Laser:set:ldi?" -response: 120.0 means the laser output current setpoint value is  
120.0 mA.  
FRONT PANEL  
LASer:SET:MDI?  
REMOTE  
The LASer:SET:MDI? query returns the laser monitor photodiode current setpoint value  
(when CALPD=0), in µA.  
:
:
:
LAS  
SET  
IPD  
?
MDI  
- where the response is the constand IPD setpoint value, in µA.  
Notes  
In local operation, the MDI setpoint is read by selecting P mode, then pressing and  
holding down the SELECT switch in the DISPLAY area of the front panel. When the µA  
indicator is blinking, the display will show the MDI setpoint.  
The monitor photodiode current is directly proportional to the laser optical output power.  
Therefore, the MDI (IPD) setpoint may be used to control optical output of the laser.  
Examples  
"las:set:mdi?" -response: 30.0, means the laser monitor photodiode current is setpoint is  
30 µA, for use in constant P mode with CALPD = 0.  
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LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
"LAS:Set:MDI?" -response: 100.0 means the laser monitor photodiode current is  
setpoint is 100 µA, for use in constant P mode with CALMD=0.  
FRONT PANEL  
REMOTE  
LASer:SET:MDP?  
The LASer:SET:MDP? query returns the laser monitor photodiode power setpoint value  
(when CALMD [CAL PD] is not zero), in mW.  
:
:
:
LAS  
SET  
P
?
MDP  
- where the response is the constand PPD setpoint, in mW.  
Notes  
In local operation, the MDP setpoint is read by selecting P mode, then pressing and  
holding down the SELECT switch in the DISPLAY area of the front panel. When the mW  
indicator is blinking, the display will show the MDP setpoint. This setpoint is used in  
constand MDP mode only.  
Examples  
"LAS:Set:MDP?" -response: 10.0, means the laser monitor photodiode feedback  
setpoint is 10.0 mW (CALPD>0).  
"Laser:Set:MDP?" -response: 25.0, means the laser monitor photodiode feedback  
setpoint is 25.0 mW (CALPD>0).  
FRONT PANEL  
LASer:STEP  
REMOTE  
The LASer:STEP command is used to increment or decrement the selected laser control  
mode setpoint by the given amount, when used with the LASer:INC or LASer:DEC  
command.  
<white  
space>  
<nrf  
value>  
:
:
LAS  
STEP  
Parameters An integer value of the step amount, in the range 1 to 9999.  
Notes  
The step of one corresponds to the smallest display resolution for the mode. For  
example, a step of one means 0.1 mA, 0.1 mW, or 1 µA (if CALPD=0).  
Examples  
"Las:Mode:i; Las:ldi 20; Las:Step 100; Las:Inc; Las:set:ldi?" -action: sets the step to  
10.0 mA, so the Las:set:ldi? query will return a value of 21.0 mA.  
"LAS:STEP 100" -action: sets the step size to 100; could mean 10.0 mA , 10.0 mW, or  
100 µA.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
LASer:STEP?  
The LASer:STEP? query is used to read back the LASer STEP value. This value is used  
to increment or decrement the selected laser control mode setpoint by the given amount  
when used with the LASer:INC or LASer:DEC command.  
:
:
LAS  
STEP  
?
- where the response is an integer value.  
Examples  
"Las:Mode:LDI; Las:Step?" -response: 1 means the step size is 0.1 mA, since Const I  
mode is in effect.  
"LAS:MODE:MDP; LAS:CALMD 1; LAS:STEP?" -response: 10 means the step size is  
1.0 mW, since Const P mode is in effect.  
FRONT PANEL  
LASer:TOLerance  
REMOTE  
The LASer:TOLerance command allows the programmer to determine the LASER  
current tolerance and time window for it to occur, in order that the operation complete flag  
be set after a "LASer:OUTput 1" command is issued or the LASER setpoint is changed.  
<white  
space>  
<nrf  
value>  
<nrf  
value>  
,
:
:
TOL  
LAS  
Parameters Two <nrf values>; the first represents the LASER current tolerance in mA with a range of  
0.1 to 100.0 mA; and the second represents the time window, in seconds, with a range of  
0.001 to 50.000 seconds.  
Notes  
The LDX-3232 defaults to a tolerance of 1.0 mA for three seconds, unless changed by  
the LASer:TOLerance command.  
If the LDX-3232 is operated in P mode, the current tolerance parameter is not used.  
Instead a fixed value of 50 µA is used for the IPD current. A fixed value of 1 mW is used for  
PPD power, and only the time window parameter may be adjusted.  
Note: If the tolerance is set too tight it may never be achieved. This is due to the calibration  
of the setpoint and measurement values.  
Examples  
"Las:Tol 0.5,10" -action: the LDX-3232's LASER current source will be in tolerance when  
the LASER current is within 0.5 mA for 10.000 seconds.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
LASer:TOLerance?  
REMOTE  
The LASer:TOLerance? query allows the programmer to determine how the LASER  
current tolerance is set.  
:
:
LAS  
TOL  
?
- where the response consists of two values, the first is the current tolerance in mA and  
the second is the time window, in seconds.  
Notes  
The tolerance of the LDX-3232 LASER current may be used to delay programming after  
an "LASer:OUTput 1" command is issued or the setpoint is changed.  
A change of the output into or out of tolerance flag sets a flag in the LASER status event  
register and so entering or exiting LASER current tolerance may be used to generate  
service requests.  
Examples  
"Las:Tol?" -response: "0.2,5.0", means the LDX-3232 has a LASER current tolerance  
setting of 0.2 mA with a time window of 5.000 seconds.  
"LASER:TOL?" -response: "1.0,20.0", means the LDX-3232 has a LASER current  
tolerance setting of 1.0 mA with a time window of 20.000 seconds.  
FRONT PANEL  
MESsage  
REMOTE  
The MESsage command allows the user to enter an ASCII string of up to 16 non-NULL  
characters. This command may be useful for storing messages that relate to a test or  
configuration.  
<white  
space>  
:
<ascii  
string>  
MES  
Parameters An ASCII string that is 1 - 16 bytes in length.  
Notes  
The message may contain any ASCII character, but will be terminated when a NULL  
terminator character is received. If the message has less than 16 bytes, the software will  
fill the remaining message space with the space character. After 16 bytes have been  
entered, the software will null-terminate the string.  
Examples  
MESSAGE "This is a test." -action: The string, "This is a test. " will be stored in  
non-volatile memory.  
Mes "Test 3" -action: The string, "Test 3  
" will be stored in non-volatile memory.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
MESsage?  
The MESsage? query returns the previously stored message. This message will always  
be 16 bytes long and enclosed in quotes. The message is entered via the MESsage  
command.  
:
MES  
?
- where the response is a 16-byte long character string.  
Notes  
The response data will be a 16-byte long string. If there is no previously stored message,  
the response will be "  
", all spaces.  
Examples  
"MES?" -response: "Test 3  
", means the previously stored message was "Test 3".  
"Message?" -response: "This is a test. ", means the previously stored message was  
"This is a test."  
FRONT PANEL  
RADix  
REMOTE  
The RADix command allows the programmer to select the radix type for status,  
condition, and event query response data. Decimal, binary, hexadecimal, and octal are  
allowed.  
<white  
space>  
:
RAD  
DEC  
BIN  
HEX  
OCT  
Parameters As shown above, character program data is expected.  
Notes  
DECimal is the default type. Only the first three letters of the words decimal,  
hexadecimal, binary, or octal are required.  
When the RADIX is selected, all status, condition, and event queries will return values in  
the new radix.  
In the cases where the radix is not DECimal, the flexible numeric type <nrf value> (as  
shown in the Command Reference diagrams) will be replaced by HEX, BIN, or OCT  
representation.  
All of the above radixes may be used to enter program data at any time, without the need  
for issuing the RADix command. The proper prefix must also be used with Hex (#H),  
binary (#B), or octal (#Q).  
This command may be useful for setting up status reporting blocks. The bit-wise status  
representation may be more easily read in BIN, HEX, or OCT.  
Examples  
"RAD dec" -action: the decimal radix is selected.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
"rad hex; *ESR?" -action: the hexadecimal radix is selected; -response: #H80, means  
power-on was detected.  
FRONT PANEL  
RADix?  
REMOTE  
The RADix? query allows the programmer to determine that radix type for status,  
condition, and event query response data is currently selected. Decimal, binary, octal,  
and hexadecimal are allowed.  
:
RAD  
?
- where the character response data of DEC means decimal, BIN means binary, HEX  
means hexadecimal, and OCT means octal.  
Notes  
DEC is the default type. The LDX-3232 defaults to this radix at power-up.  
The RADix command is used to select the desired radix. Once it is changed, the new  
radix will remain in effect until the power is shut off or a new RADix command is issued.  
Examples  
"RAD?" -response: Dec, means the selected radix is decimal.  
"rad?" -response: Hex, means the selected radix is hexadecimal.  
"RADIX?" -response: Oct, means the selected radix is octal.  
SECURE  
TERM  
FRONT PANEL  
REMOTE  
The SECURE command allows the service technician access to the protected user data  
command, *PUD, that is a common command. This data is normally changed only at the  
factor, and therefore the SECURE command is not needed by the user.  
FRONT PANEL  
REMOTE  
The TERM command allows the programmer to change the default  
(GPIB/IEEE488 standard) terminator to include the carriage return.  
<white  
space>  
<nrf  
value>  
:
TERM  
Parameters An <nrf value>, 0=FALSE, non-zero=TRUE  
Notes  
An altered terminator will be in the form <CR><NL><^END>. This technically takes the  
LDX-3232 out of GPIB/IEEE488 specification, but may be done for convenience when  
using non standard GPIB controllers. This termination will be sent with all output until the  
"TERM 0" command is sent or the LDX-3232 is powered off.  
Examples  
"Term 1" -temporarily sets <CR><NL><^END> as the output terminator.  
"Term 0" -sets the GPIB/IEEE488 standard <NL><^END>terminator. This is the  
LDX-3232 default value.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
REMOTE  
TERM?  
The TERM? query allows the programmer to determine whether the default  
(IEEE488.2 standard) terminator has been altered to include a carriage return.  
:
TERM  
?
- where the response is 0 or 1.  
An altered terminator will be in the form <CR><NL><^END>. This termination will be  
Notes  
sent with all output until the "TERM 0" command is sent, or the LDX-3232 is powered off.  
Examples  
"Term?" -response: 1, means that the <CR><NL><^END> terminator is temporarily  
being used.  
"Term?" -response: 0, means that the <NL><^END> terminator (GPIB/IEEE488  
standard) is being used.  
FRONT PANEL  
TIME?  
REMOTE  
The TIME? query allows the programmer to determine how much time has passed since  
the LDX-3232 was last powered up.  
:
TIME  
?
- where the response is character data in the form: hours:minutes:seconds.  
The TIME clock is independent of the TIMER clock.  
Notes  
Examples  
"Time?" -response: 1:02.36, means that one minute and 2.36 seconds have passed  
since the LDX-3232 was powered up.  
"TIME?" -response: 32:00:76, means that 32 minutes and 0.76 seconds have passed  
since the LDX-3232 was powered up.  
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COMMAND REFERENCE  
LDX-3232 Device-Dependent Command Reference  
C H A P T E R  
4
FRONT PANEL  
TIMER?  
REMOTE  
The TIMER? query allows the programmer to determine how much time has passed  
since the last TIMER? query was issued.  
:
TIMER  
?
- where the response is character data that represents hours:minutes:seconds.  
Notes  
Each time the TIMER? query is issued, the timer is reset to 0 and the elapsed time since  
the last TIMER? query is returned.  
The timer counter is initially set at power-up, the same as the TIME? counter. So the first  
time the TIMER? is issued its response will be the same as if a TIME? query's response.  
Examples  
"Timer?" -response: 00:02:00.31, means the LDX-3232 has been on for two minutes and  
0.31 seconds since the last TIMER? query was issued.  
"TIMER?" -response: 00:00:12.03, means the LDX-3232 has been on for 12.03 seconds  
since the last TIMER? query was issued.  
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FUNCTIONS AND FEATURES  
Saving and Recalling from the Front Panel  
C H A P T E R  
5
C H A P T E R  
5
FUNCTIONS AND FEATURES  
This chapter introduces you to the LDX-3232 High Compliance Current Source  
functions and operating features such as event triggering, analog modulation of  
laser injection current, and Save and Recall.  
Saving and Recalling from the Front Panel  
For applications where you might need to alternate between particular instrument  
configurations, the LDX-3232 Current Source offers a unique SAVE and RECALL  
feature. The SAVE feature allows you to easily store all front panel settings for any  
given instrument configuration. These settings, that are stored in one of ten  
memory bins, can be retrieved at any time with the RECALL function. This saves  
setup time, and it reduces the chance of setup error for tests that are periodically  
repeated. For example, using the configuration described in Chapter 2 where the  
Current Source is operating in Constant Current mode, the instrument parameters  
saved by using the SAVE function would be Constant Current Mode, 2000 mA  
range, a limit setpoint of 1750 mA, a laser current setpoint of 1500 mA, and  
Display Mode I. Once this setup is saved, the LDX-3232 Current Source may be  
configured for another unique setup. You can recall the original setup for the first  
experiment any time using the RECALL function.  
To enter the SAVE/RECALL mode, press the SELECT switch in the PARAMETER  
section until the SAVE indicator LED becomes lit and the unit displays the SAVE  
"bin" on the display. If another bin number is desired, press and hold the SET  
switch and rotate the adjust knob until the desired bin number is displayed.  
Releasing the SET switch completes the SAVE operation and all of the instrument  
parameters are saved to the indicated bin number as they appear on the front  
panel.  
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FUNCTIONS AND FEATURES  
Saving and Recalling Under Remote Operation  
C H A P T E R  
5
To recall a previously saved instrument setup, press the SELECT switch until the  
RECALL indicator led becomes lit. The instrument will display a RECALL "bin"  
number on the display. If you desire to change the RECALL bin, press and hold  
the SET switch and rotate the adjust knob until the desired bin number is  
displayed. Releasing the SET switch completes the RECALL operation. The  
instrument is restarted and the front panel parameters are reconfigured to the new  
parameters saved under that bin number.  
The factory default values for front panel parameters may be restored by recalling  
"bin" zero (0). See Table 2.1 for the default settings.  
Saving and Recalling Under Remote Operation  
For saving under remote operation, use the command *SAVx, where x is the  
desired "bin" number (1-10). For a recall under remote operation, use the  
command *RCLx, where x is the desired "bin" number (0 - 10).  
Using the Laser Compliance Voltage Adjustment  
For applications where you need to have critical protection of the laser, we  
recommend the following. Using a 1 Ω resistor or other non-critical load, set the  
LASER voltage limit as described in Chapter 2.  
Then with the LASER output on, slowly increase the LASER current and watch  
the LASER voltage measurement. Press the (DISPLAY) SELECT push button to  
see the voltage. At about 0.25 V below the LASER voltage limit value, the  
VOLTAGE LIMIT warning indicator will become lit on the display. Continue to  
adjust the current upwards until the voltage limit is reached and the output is shut  
off. Record the voltage at that the LASER output shuts off. It should be within the  
specification of the LASER voltage limit accuracy. However, there is typically  
some offset error. For example, if the LASER voltage limit is set to 5.0 V, the  
actual voltage where it shuts off may be 4.9 V. This error term of 0.1 V should be  
considered when setting the LASER compliance voltage limit.  
The closer the LASER voltage limit shut off point is to the operating voltage of  
your laser, the faster the circuit will work in the event of an open circuit. Some  
experimentation may be necessary for optimum results.  
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FUNCTIONS AND FEATURES  
Using the LDX-3232 Current Source’s Trigger Function  
C H A P T E R  
5
Using the LDX-3232 Current Source’s Trigger Function  
For applications where you need to synchronously initiate a measurement task  
from a remote instrument with the LDX-3232 Current Source, the Current Source  
offers a trigger output signal. The TTL pulse is initiated with any remote change in  
setpoint of the laser current source. A typical application for utilization of this  
feature is laser characterization tasks where an L-I curve is generated. For a  
programmed step in laser current, a light measurement can be triggered for each  
step in laser current. The trigger output is enabled only in remote mode via the  
GPIB/IEEE 488 GPIB Interface.  
The trigger output is available via a standard BNC connector on the rear panel of  
the LDX-3232 Current Source. See Figure 5.1. The TTL pulse is approximately  
13 µs wide and has a delay time of about 10-12 ms after the current setpoint is  
changed via GPIB. This delay does not include the GPIB transmission time. The  
time for any command to be sent via GPIB depends on the interface hardware  
and software control. The current setpoint may be changed by the LAS:LDI,  
LAS:INC, or LAS:DEC commands.  
Note: The minimum step change time required for a corresponding trigger pulse is 20 ms.  
Care should be used with respect to the timing of any setpoint commands in relation to the  
actual hardware function. The INC and DEC commands have a minimum step time of  
about 20 ms that allows for the hardware initiation of a setpoint change and the settling of  
the output. The LAS:LDI command does not have any fixed delay for settling. With this  
command, some trigger pulses may be missed if the program step time is less than the  
20 ms minimum.  
A one shot trigger pulse will occur on power up of the instrument due to the states of the  
processor I/O.  
Figure 5.1 LDX-3232 Rear Panel  
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FUNCTIONS AND FEATURES  
Using the LDX-3232 Current Sources’s BNC Interlock Connection  
C H A P T E R  
5
Using the LDX-3232 Current Sources’s BNC Interlock  
Connection  
The LDX-3232 BNC interlock connection is designed to allow an external  
emergency input signal to turn the current output off. The BNC interlock is TTL  
compatible and configured to be normally closed (as opposed to the DB-9  
interlock connection, that is normally open). The BNC interlock connection, when  
left unconnected, is pulled to a logic high with a 100 kΩ resistor. High values  
(+5 V) will keep the interlock closed (current source in the operational state), while  
low values (0 V) will open the BNC interlock (forces the output off). Once the  
BNC interlock is opened, the output will stay off until the interlock is closed again,  
and you re-enable the output.  
BNC Interlock Usage Example  
When using the LDX-3232 Current Source to drive a temperature controlled laser  
diode, the BNC interlock can be used to accept an error signal from the laser  
diode temperature controller unit. Linking the LDX-3232 Current Source to a  
temperature controller* with the ability to signal when its temperature control has  
gone outside of some tolerance window will allow the LDX-3232 to safely shutoff  
its output before thermal damage occurs to the laser diode.  
*The ILX Lightwave LDT-5900 series of temperature controllers include an output  
BNC connector that is compatible with the BNC interlock feature of the LDX-3232.  
The output BNC connector of the LDT-5900 has a TTL compatible output signal  
that will signal when the temperature control has gone outside of a programmable  
temperature window. For more information about the LDT-5900 series of  
temperature controllers, please call 1-800-459-9459 (USA or Canada only),  
1-406-556-2481 (International), or go to www.ilxlightwave.com.  
Modulating the Laser Current Source  
The LDX-3232 Current Source allows a modulated signal to be superimposed on  
the source output current. For example, assume you are using an LED for your  
experiment where you need to operate the LED in constant current at POP  
=
100 mW, with a modulated signal from 3 to 30 kHz. The experiment requires the  
LDX-3232's laser Current Source to be configured for the 2000 mA range, high  
bandwidth mode with a limit of 1750 mA. The allowable bandwidth of the  
modulated analog signal, defined as the 3 dB roll off point, is dependent on the  
output current range and the mode (constant current low/high bandwidth). See the  
section, LASER CURRENT SOURCE SPECIFICATIONS, in Chapter 1 for  
external analog modulation bandwidth specifications.  
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FUNCTIONS AND FEATURES  
Modulating the Laser Current Source  
C H A P T E R  
5
Setting up the Current Source for a modulated laser injection  
current is easy. The (MOD) EXTERNAL connector (BNC) on the  
front panel is the input for the modulated signal. Connect a  
modulating voltage signal from a standard function generator, for  
example, to this connector. The modulation port input impedance  
is 1 kΩ. The transfer function for the low and high current ranges  
of the LDX-3232 are 200 mA/V and 400 mA/V.  
Set the LDX-3232 in Constant Current High Bandwidth  
Mode by selecting IHBW in the MODE section of the front  
panel. Do this by toggling the (MODE) SELECT push  
button until the IHBW indicator is illuminated. Repeatedly  
pressing the (MODE) SELECT switch cycles through the  
current (I), optical power (P), or high bandwidth current  
(IHBW) control modes.  
Next, set the current source range by selecting the  
2000 mA range indicated by the accompanying LED. You  
will need to press the select push button twice to change  
the range. It must be pressed twice quickly (within less than  
one second) to switch between modes, and the current  
source output must be off (MODE ON indicator unlit) in  
order to change ranges.  
The limit clamp function for DC output current applies to the modulated current as  
well protecting your laser in any mode. To accomplish setting the current source  
limit, use the (PARAMETER) SELECT push button LIM I. Press the  
(PARAMETER) SET push button and rotate the adjust knob. Set the limit to  
1750 mA. Once the (PARAMETER) SET push button is released, the new  
parameter value is stored in non-volatile memory.  
When the laser current limit is reached, the CURRENT LIMIT error indicator  
flashes. The current limit setting is independent of the voltage drop of the device  
connected to the laser output, and therefore, no dummy load is required for  
precise adjustment of the current limit. Furthermore, since the current limit  
circuitry is fully independent of the main current control, the current limit can be  
adjusted safely, even while the current source output is active.  
Now you are ready to modulate the laser injection current. To enable the Current  
Source output, press the push button labeled (MODE) OUTPUT. The  
accompanying LED labeled ON will illuminate indicating that the laser current  
source's output is enabled. The instrument will drive the current source to the  
value set by the corresponding MODE setpoint. Turn on the function generator  
(modulation source) to inject the modulation signal.  
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FUNCTIONS AND FEATURES  
Modulating the Laser Current Source  
C H A P T E R  
5
To disable the output, press the OUTPUT push button again. When the LDX-3232  
current output is off, an internal short is placed across the output. This short will  
prevent the modulation signal from reaching the LED in our example experiment.  
Thus, it is safe to disconnect the test device (LED) when the LDX-3232's output is  
off, regardless of the presence of the modulation signal.  
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CALIBRATION AND TR OUBLESHOOTING  
C H A P T E R  
6
Calibration Overview  
C H A P T E R  
6
CALIBRATION AND TROUBLESHOOTING  
This chapter describes calibration of your LDX-3232 Series Current Source.  
Descriptions of the required test instruments, calibration conditions, and the  
detailed procedures for calibration of the instrument's Laser Diode Current Source  
are included. A troubleshooting guide is also offered for some of the more  
common failure symptoms. This chapter is divided into three major sections, local  
(front panel) calibration, remote (through the GPIB Interface) calibration, and a  
troubleshooting guide.  
Calibration Overview  
There are several calibrations to be performed to completely calibrate your  
LDX-3232 Current Source. The Laser Diode Current Source calibration consists  
of calibrating the current source in both ranges and both modes (low and high  
bandwidth), calibrating the photodiode monitor feedback ammeter and finally the  
forward voltage measurement. The current limits are calibrated internally by the  
instrument as part of the calibration process.  
Your LDX-3232 Current Source can be calibrated with the case closed. It should  
be calibrated every 12 months or whenever performance verification indicates that  
calibration is necessary, such as differences between setpoint and measurement  
display values that exceed the accuracy specification. Calibrate the instrument  
under laboratory conditions. We recommend calibration at 23°C ± 1.0°C. When  
necessary, however, the LDX-3232 Current Source may be calibrated at its  
intended use temperature if this is within the specified operating temperature  
range of 0 to 40°C.  
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CALIBRATION AND TR OUBLESHOOTING  
Recommended Equipment  
C H A P T E R  
6
Finally, the LDX-3232 Current Source should be allowed to warm up for at least  
one hour before calibration.  
Recommended Equipment  
Recommended test equipment for calibrating the LDX-3232 Current Source is  
listed in Table 6.1. Equipment other than that shown in the table may be used if  
the specifications meet or exceed those listed.  
Table 6.1 Recommended Test Equipment  
Description  
DMM  
Manufacturer/Model  
HP 3457A  
Specification  
DC Amps (@ 1.0 A): ±0.02%  
Resistance (@ 10 Ω): ±0.02%  
0.1 µA or 0.1 mV resolution  
It will be necessary to connect various loads and circuits to the outputs of each  
current source for the calibration procedure. A schematic is shown in Figure 6.1  
for the photodiode calibration circuit with the required components listed in Table  
6.2. Also, the devices required for other calibration loads are listed in Table 6.2.  
Table 6.2 Required Calibration Components  
Laser Current Source Calibration  
Current Source Calibration, all models  
Voltage Measurement Calibration  
10 Ω, 20 W resistor, low TCR  
15 Ω, 5 W resistor, low TCR  
PD Monitor Calibration (See Schematic in Figure 6.1)  
PD Calibration Circuit  
49 Ω resistor, 1%, 1/4 W  
100 Ω resistor, 1%, 1/4 W  
1.0 MΩ resistor, 1%, 1/4 W  
5 Ω, 1%, 10W  
R1  
R2  
R4  
R3  
U1  
TIL 117 opto isolator  
90  
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Local Calibration of the LDX-3232 Current Source  
9-Pin D-Sub  
LD Cathode (5)  
LD Anode (9)  
R4  
1 M  
PD Cathode + (6)  
PD Anode - (7)  
R2  
100  
R3  
R1  
49  
V
U1 TIL117  
Voltmeter  
6
5
1
A
Ipd Current  
2
3
Ammeter  
4
CALIBRATION CIRCUIT  
Figure 6.1 I Calibration Circuit  
PD  
Local Calibration of the LDX-3232 Current Source  
There are three calibration adjustments required for the LASER current source of  
the LDX-3232 Current Source. They are calibration of the constant current source  
for both bandwidths and ranges, calibration of the laser voltage measurement,  
and calibration of the constant light power (IPD) feedback circuits.  
The LDX-3232 Current Source implements a two-point calibration for the Laser  
current source. Two currents (approximately 80% and 20% of FS) are applied to  
a test load, and the resulting actual currents are fed back (by the user) to the  
Current Source. The Laser Current Source calibration program uses the two sets  
of data to calculate new calibration constants. These calibration constants are  
used to set the actual current output of the current source.  
Current Source Calibration  
The following procedure is for calibrating each range of the current source.  
Calibration must be performed on both bandwidth modes. A total of four  
calibrations will be performed on the current source. Start with the low range, low  
bandwidth mode. Configure the Laser Current Source in the following state:  
Function  
State  
MODE  
I (constant current low bandwidth)  
low (lowest per instrument model)  
90% of FS (full scale of range)  
80% of FS  
RANGE  
CURRENT LIMIT  
SETPOINT  
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C H A P T E R  
6
a.  
b.  
Measure and record the resistance of a 1Ω, 20 W resistor (A 4-wire [Kelvin]  
resistance measurement is recommended.) Connect the load resistor across the  
LASER output terminals (Laser Anode and Laser Cathode) on the 9 pin connector of  
the rear panel.  
Connect the calibrated DMM across the load resistor. Configure the multimeter to  
measure voltage in volts. You will be calculating the actual Laser current in the  
following manner using Ohm's Law.  
I = V/ R  
--where V is the accurately measured voltage across the resistor, and R is the  
accurately measured load resistance in Ohms. I is the actual Laser current in Amps.  
Note: Check the current measuring range of your multimeter. You may be able to measure  
Laser Output current in mA by connecting the meter directly to the outputs of the Laser  
Current Source.  
c.  
Press the (MODE) ON switch to turn the current source output on. The output must  
be on in order to enter the LASER I calibration mode.  
d.  
Enter the LASER I calibration mode by pushing the (GPIB) LOCAL and (DISPLAY)  
SELECT switches at the same time. The display will blank and the Current Source  
will drive the current output to the setpoint and the Display will indicate output current  
in mA.  
e.  
f.  
Calculate the actual current through the load as described in step b. Press and hold  
in the (PARAMETER) SET switch and turn the adjust knob until the display indicates  
the calculated actual current.  
Release the (PARAMETER) SET switch. After the (PARAMETER) SET switch is  
released, the Current Source will drive the current output to about 25% of the first  
calibration setpoint.  
g.  
h.  
Calculate the measured current again through the load resistor.  
Press and hold in the (PARAMETER) SET switch and turn the adjust knob until the  
display indicates the actual current as calculated in step g.  
i.  
Release the (PARAMETER) SET switch to accept the second calibration point. After  
the (PARAMETER) SET switch is released, the Current Source will calculate the  
calibration constants and store them to nonvolatile memory. In low bandwidth  
calibration mode, the LDX-3232 Series Current Source will also perform current limit  
calibration, indicated by the CURRENT LIMIT LED flashing.  
j.  
Turn the current source output off. Change the Mode to I  
(high bandwidth  
HBW  
constant current mode). Repeat the calibration procedure as described above.  
k.  
Change the output range to high range and repeat the calibration procedure as  
described above.  
I
Current Calibration  
PD  
The following procedure is for calibrating the LASER IPD (PD monitor) setpoint  
and measurement. This procedure calibrates the feedback circuits for constant  
IPD and constant PPD modes. When these values are reached and are stable, the  
user enters the actual value of the monitor current, measured with a DMM. The  
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Local Calibration of the LDX-3232 Current Source  
LDX-3232 Series Current Source then automatically calibrates the LASER  
feedback circuits.  
Configure the Current Source in the following manner for the Laser Current  
Source calibration:  
Function  
State  
MODE  
P (constant power)  
set equal to zero  
90% of FS (full scale of range)  
80% of FS  
CAL PD  
CURRENT LIMIT  
I
SETPOINT  
PD  
a.  
With the LASER output off, connect a calibrated ammeter to the PD Anode output of  
the Laser Current Source output connector (9 pin on rear panel), and connect the  
circuit of Figure 6.1 to the LASER and PD outputs with the correct load resistor for  
the Current Source model you are calibrating (See Table 6.2).  
Note: If a precision ammeter is not available, use a zero-Ohm jumper in place of the  
ammeter. Then, place a calibrated DMM (with 0.1 mV resolution) to measure the voltage  
across the resistor, R1, as shown in Figure 6.1. Calculate the current in the following steps  
by using Ohm's Law:  
I = V/ R  
--where V is the accurately measured voltage across the resistor, and R is the accurately  
measured load resistance. I is the actual photodiode current to be measured by the  
LDX-3232 Current Source. (A 4-wire [Kelvin] resistance measurement is recommended.)  
b.  
Press the (MODE) ON switch to turn the current source output on. Verify proper  
operation, i.e. the I measurement (via DMM) and setpoint should be close, and the  
PD  
unit should not be in current limit.  
c.  
Press the (GPIB) LOCAL and FINE switches at the same time to place the Current  
Source in its I Current Calibration mode.  
PD  
After a few seconds the display will show the I setpoint value.  
PD  
d.  
After the value on the display is stable (has not changed by more than one digit for  
several seconds) the LDX-3232 Current Source is ready for the actual I value to be  
PD  
entered.  
Press and hold in the (PARAMETER) SET switch and turn the adjust knob until the  
display shows the actual monitor current, as shown on the calibrated ammeter (or the  
calculated I value from Step a).  
PD  
e.  
f.  
Release the (PARAMETER) SET switch to store the first calibration value. The  
Current Source will then set the second calibration current, approximately one-fourth  
(1/4) of the original current. (For example, if the first calibration setpoint was 4000 µA,  
the second setpoint will be about 1000 µA.)  
Press and hold in the (PARAMETER) SET switch and turn the adjust knob until the  
display indicates the actual current as measured by the ammeter or as calculated.  
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C H A P T E R  
6
g.  
Release the (PARAMETER) SET switch to accept the second calibration point. After  
the (PARAMETER) SET switch is released, the LDX-3232 Series Current Source will  
calculate the calibration constants and store them to nonvolatile memory.  
Laser Forward Voltage Measurement Calibration  
The following procedure is for calibrating the LASER voltage measurement.  
Configure the Current Source in the following manner for the Laser Current  
Source Voltage calibration:  
Function  
State  
LASER MODE  
RANGE  
I (constant current low bandwidth)  
2000 mA  
CURRENT LIMIT  
I SETPOINT  
Set to FS (full scale of range)  
800 mA  
a.  
With the current source output off, connect a calibrated voltmeter, in parallel with a  
resistor (15 Ω, 5 W), to the LASER output (Laser Anode and Laser Cathode) on the  
rear panel of the Current Source.  
b.  
c.  
Press the (MODE) ON switch to turn the current source output on. The current  
source output must be on in order to enter the LDV calibration mode.  
Enter the LASER V calibration mode by pushing the (GPIB) LOCAL and RANGE  
switches at the same time. The display will blank and the Current Source will drive  
the LASER current output to the respective setpoint and the display will indicate  
forward voltage in Volts.  
d.  
e.  
Enter the measured voltage (in volts). Press and hold in the (PARAMETER) SET  
switch and turn the adjust knob until the display indicates the measured voltage.  
Once the actual voltage value is entered, the Current Source will set the current to  
approximately one-fourth (1/4) of the original value. It will then expect the second  
calibration voltage point.  
f.  
Input the second actual (measured) LASER forward voltage as in Step d.  
g.  
Once the second actual voltage value is entered, the Current Source will store the  
new calibration constants.  
This ends the section on front panel calibration of your LDX-3232 Current Source.  
The next section discusses calibration through the GPIB/IEEE488 interface.  
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Remote Calibration of the LDX-3232 Current Source  
Remote Calibration of the LDX-3232 Current Source  
The LDX-3232 Current Sources can be calibrated remotely via the GPIB  
Interface. All of the required calibration commands are listed in Table 4.1 in  
Chapter 4. The procedures below are general guidelines for writing a program to  
calibrate your instrument.  
Note: The operation complete flag (bit 0 of the Standard Event Status Register) may be  
used to trigger a service request. This type of interrupt is enabled by setting bit 0 of the  
Service Request Enable register (via the *ESEcommand) and bit 5 of the Service Request  
Enable register (via the *SREcommand). Service request (SRQ) handling depends on your  
GPIB hardware. Refer to your GPIB user's manual for details.  
After a calibration value is entered, the *OPC?query may be used to determine when the  
calibration sequence is done. However, the *OPC, *WAIcommand, or *OPC?query should  
not be issued until after the expected calibration value is entered, or the system will "hang".  
This happens because the LDX-3232 Current Source will wait indefinitely for an input, yet  
not allow any input until the calibration is finished.  
Current Source Calibration  
There are three calibration adjustments required for the LDX-3232 Current  
Source. They are calibration of the constant current source for both bandwidths  
and ranges, calibration of the laser voltage measurement, and calibration of the  
constant light power (IPD) feedback circuits.  
The LDX-3232 Current Source implements a two-point calibration for the current  
source. Two currents (approximately 20% and 80% of FS) are applied to a test  
load, and the resulting actual currents are fed back (by the user) to the current  
source. The laser current source calibration program uses the two sets of data to  
calculate new calibration constants. These calibration constants are used to set  
the actual current of the current source.  
The following procedure is for calibrating each range of the current source. Start  
with the low range. After calibration is complete in this range, switch to the high  
range and repeat the procedure.  
Configure the current source in the following manner for the laser current source  
calibration:  
Function  
State  
GPIB COMMAND  
LAS:MODE:ILBW  
LAS:RAN x  
LASER MODE  
RANGE  
I (constant current low bandwidth)  
Low (lowest per instrument model)  
90% of FS (full scale of range)  
80% of FS  
LIMIT  
LAS:LIM:Ix  
LAS:LDI  
SETPOINT  
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C H A P T E R  
6
a.  
b.  
Measure and record the resistance of a 1 Ω, 20 W resistor. (A 4-wire [Kelvin]  
resistance measurement is recommended.) Connect the load resistor across the  
LASER output terminals (Laser Anode and Laser Cathode) on the 9 pin connector of  
the rear panel.  
Connect the calibrated DMM across the load resistor. Configure the multimeter to  
measure voltage in volts. You will be calculating the actual Laser current in the  
following manner using Ohm's Law.  
I = V/ R  
--where V is the accurately measured voltage across the resistor, and R is the  
accurately measured load resistance in Ohms. I is the actual Laser current in Amps.  
c.  
d.  
e.  
The current source output must be on in order to enter the LASER I calibration mode.  
Enter the LAS:OUTPUT ONcommand to turn the current source output on.  
Enter the LASER I calibration mode by issuing the LAS:CAL:LDIcommand. The  
display will indicate a current in mA.  
Input the first actual (measured) output current (as an <nrf value>) via the  
LAS:LDI <nrf value>command.  
If this value is to be measured and entered remotely via a GPIB controlled DMM, for  
example, the measured value of the current should not be entered until the  
LDX-3232 Series Current Source is ready to receive it. The Current Source will be  
ready to receive the new measured value when, after a LAS:CAL:LDI?query is  
sent, the response from the Current Source is "1".  
f.  
Once the newly measured I value is entered via the LAS:LDIcommand, the Current  
Source will apply a new current equal to about 25% of the previous set current.  
g.  
h.  
Input the second actual (measured) output current (as an <nrf value>) as in  
Step e.  
Once the second actual I value is entered via the LAS:LDIcommand, the new  
calibration constants will be calculated and stored into non-volatile memory. In low  
bandwidth calibration mode, the LDX-3232 Current Source will also perform current  
limit calibration as indicated by the CURRENT LIMIT LED flashing. The OPC?query  
may be used (after the LAS:LDIvalue is sent) to determine when the calibration is  
completed. Or, wait about two seconds before continuing with other GPIB  
commands.  
i.  
Turn the current source output off. Change the Mode to I  
(high bandwidth  
HBW  
constant current mode) with the LAS:IHBWcommand. Repeat the calibration  
procedure as described above.  
I
Current Calibration  
PD  
The following procedure is for calibration the LASER IPD constant current source.  
This procedure calibrates the feedback circuits for constant IPD and constant PPD  
modes. When these values are reached and are stable, the user enters the actual  
value of the current, as measured by an external DMM. The LDX-3232 Current  
Source then automatically calibrates the LASER feedback circuits.  
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Remote Calibration of the LDX-3232 Current Source  
Configure the current source in the following manner for the laser current source  
calibration:  
Function  
LASER MODE  
RANGE  
State  
GPIB COMMAND  
LAS:MODE:ILBW  
LAS:RAN x  
I (constant current low bandwidth)  
Low (lowest per instrument model)  
90% of FS (full scale of range)  
80% of FS  
LIMIT  
LAS:LIM:Ix  
LAS:LDI  
I
SETPOINT  
PD  
a.  
With the LASER output off, connect a calibrated ammeter to the PD Anode output of  
the Laser Current Source output connector (9 pin on rear panel), and connect the  
circuit of Figure 6.1 to the LASER and PD outputs with the correct load resistor for  
the Current Source model you are calibrating (See Table 6.2).  
b.  
c.  
d.  
Enter the LAS:OUT ONcommand to turn the LASER output on. Verify proper  
operation, i.e. the IPD output should be close to the setpoint, and the unit should not  
be in current limit (read the limit status via the LAS:COND?query, bit 0).  
Enter the LAS:CAL:MDIcommand to place the Current Source in its LASER Current  
Calibration mode. The Current Source will increase the laser current output until the  
current at the PD monitor (I ) inputs equals the targeted setpoint.  
PD  
After a few seconds, the Current Source will be ready for the actual I  
current to be  
PD  
entered via the LAS:MDI <nrf value>command. The measured value of the  
current should not be entered until the Current Source is ready to receive it. The  
Current Source will be ready to receive the current value when, after a  
LAS:CAL:MDI?query is sent, the response from the Current Source is "1".  
e.  
Once the actual I value is entered via the LAS:MDI <nrf value>command, the  
PD  
Current Source will store the new calibration value. It will then set the output to  
approximately one-fourth (1/4) of the original current. (For example, if the first  
calibration setpoint was 4000 µA, the second setpoint will be 1000 µA.) Then, it will  
be ready to receive the second calibration value.  
f.  
Input the second actual (measured) monitor diode current (as an <nrf value>) as  
in Step d.  
g.  
Once the second actual IPD value is entered via the LAS:MDIcommand, the new  
calibration constants will be calculated and stored into non-volatile memory. The  
OPC?query may be used (after the LAS:MDIvalue is sent) to determine when the  
calibration is completed. Or, wait about two seconds before continuing with other  
GPIB commands.  
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6
Laser Forward Voltage Measurement Calibration  
The following procedure is for calibrating the LASER voltage measurement.  
Configure the current source in the following manner for the laser current source  
voltage calibration:  
Function  
State  
GPIB Command  
LAS:MODE:ILBW  
LAS:RANGE1  
LASER MODE  
RANGE  
I (constant current low bandwidth)  
2000 mA  
CURRENT LIMIT  
I SETPOINT  
Set to FS (full scale of range)  
400 mA  
LAS:LIM:Ix  
LAS:LDI 400  
a.  
With the LASER output off, connect a calibrated voltmeter, in parallel with a resistor  
(15 Ω, 5 W), to the LASER output (Laser Anode and Laser Cathode) on the rear  
panel of the Current Source.  
b.  
c.  
d.  
The current source output must be on in order to enter the LDV calibration mode.  
Enter the LAS:OUT ON command to turn the current source output on.  
Enter the LAS:CAL:LDVcommand to place the Current Source in its LASER Voltage  
Calibration mode.  
Enter the measured voltage (in volts) via the LAS:LDV <nrf value>command.  
The measured value of the voltage should not be entered until the LDX-3232 Current  
Source is ready to receive it. The current source will be ready to receive the voltage  
value when, after a LAS:CAL:LDV?query is sent, the response from the Current  
Source is "1".  
e.  
Once the actual voltage value is entered via the LAS:LDV <nrf value>command,  
the Current Source will set the current to approximately one-fourth (1/4) of the  
original value. It will then expect the second calibration voltage point.  
f.  
Input the second actual (measured) LASER forward voltage (as an <nrf value>)  
as in Step d.  
g.  
Once the second actual voltage value is entered via the LAS:LDVcommand, the  
Current Source will store the new calibration constants. The OPC?query may be  
used (after the LAS:LDVvalue is sent) to determine when the calibration is  
completed. Or, wait about two seconds before continuing with other GPIB  
commands.  
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Troubleshooting Guide  
Troubleshooting Guide  
This section is a guide to troubleshooting the LDX-3232 Current Sources. Some  
of the more common symptoms are listed here, and the appropriate  
troubleshooting actions are given. We recommend that the user start at the  
beginning of this guide. Read the symptom descriptions, and follow the steps for  
the corrective actions that apply. If you encounter problems that are beyond the  
scope of this guide, contact your ILX Lightwave customer service representative.  
Symptom  
Corrective Actions  
GENERAL  
LDX-3232 unit will not power up  
Check AC power line voltage and power cord connection.  
Power on, but display is frozen  
and switches don’t operate  
This may occur if the instrument loses power (AC line) briefly.  
turn the power switch off and on again to restart.  
Displays E514 on power up on  
display  
Hold (GPIB) LOCAL button, RANGE button and FINE button as  
you are powering up the instrument. This clears the laser board  
EEPROM, LLLLL will be displayed on the display; the laser  
current source must be recalibrated.  
Instrument resets at power up or  
any LASER mode change  
Hold (GPIB) LOCAL button, RANGE button and FINE button as  
you are powering up the instrument. This clears the laser board  
EEPROM, LLLLL will be displayed on the display; the laser  
current source must be recalibrated.  
LASER CURRENT SOURCE  
Power on, but no current output  
Check interlock pins on LASER input connector on instrument  
rear panel; these pins must be shorted either directly or though  
a switch.  
If OPEN CIRCUIT indicator is lit, check the load connections  
and then try again.  
Check the OUTPUT ON switch, the corresponding LED should  
be lit.  
Output current at limit; can’t be  
lowered  
If POWER mode is used, check the monitor diode (feedback)  
connections; try reversing the polarity of the monitor  
photodiode; also check the photodiode bias adjustment on the  
rear panel.  
If in I or I  
mode, check the current setpoint and I LIMIT  
HBW  
setting; setting the output below the limit may require several  
turns of the adjust know if the setpoint is much greater than the  
desired limit setting.  
Output goes off intermittently  
Check the interlock circuit; an intermittent interlock will turn the  
output off.  
Check that the AC power cord connection is secure; power line  
drop-outs may reset the unit and when power is restored, the  
output will be off.  
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6
Symptom  
Corrective Actions  
Unable to adjust output  
Check the I LIMIT parameter for the output range in use, see  
that it is set above 0 mA.  
Power mode operation has high  
output current, but little or no  
power measured  
Check back panel PD BIAS; if set too low, may act as an open  
feedback loop; if in doubt, set the PD BIAS to mid range (2.5 V)  
Output exceeds power limit  
The “power limit” is not a hardware limit. It only serves as a  
warning that the power measurement has exceeded the limit  
setpoint. Normally this limit will cause the output to shut off. This  
feature can be defeated via the LAS:ENABLE:OUTOFF  
command.  
Open circuit error occurs during  
calibration  
Check load connections; check that measuring meter does not  
auto-range (use non-auto-ranging modes).  
Calibration is aborted  
unintentionally  
Calibration modes will be aborted if an open circuit is detected.  
VOLTAGE LIMIT indicator blinks  
This indicates a voltage limit error; check laser connections. A  
high impedance may cause this condition.  
Open circuit error E503 or voltage  
limit error E505 prevents output  
from reaching desired value  
The LDX-3232 instruments have an adjustable laser  
compliance voltage. Check to see if the LASER voltage limit  
setting is too low (Chapter 2); check laser connections.  
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Error Messages  
Error Messages  
In the event of a hardware error condition, error messages will be displayed on the  
display. In most cases, the error message will appear for three seconds. In some  
cases the error code display will remain until the user changes display modes. In  
the case of multiple error messages, the display may sequentially show each  
message for three seconds. In addition to the hardware errors, GPIB errors may  
be read via the ERR?query. Table 3.4 lists the numerical error ranges by function.  
Table 3.5 contains all of the error messages that may be generated. Not all of  
these messages may appear on the front panel displays. Some refer to GPIB  
activities only.  
In remote operation, the errors can be read by issuing the ERR?query. When this  
is done, all of the error messages that are resident in the error queue are returned  
(up to 10 may be stored). Reading the error queue via GPIB clears the error  
queue.  
Table 6.3 Error Code Classifications  
Error Code Range  
E-001 to E-099  
E-100 to E-199  
E-200 to E-299  
E-300 to E-399  
E-500 to E-599  
Area of Operation  
Internal Program Errors  
Parser Errors  
Execution Control Errors  
GPIB Errors  
LASER Control Errors  
Table 6.4 LDX-3232 Series Error Codes  
Error Code Explanation  
E-001  
E-103  
E-104  
E-105  
E-106  
E-123  
E-124  
E-126  
Memory allocation failure  
<DEFINITE LENGTH ARBITRARY BLOCK PROGRAM DATA> length too long  
<NON-DECIMAL NUMERIC PROGRAM DATA> type not defined  
<DECIMAL PROGRAM DATA> exponent not valid  
<DECIMAL PROGRAM DATA> digit expected  
Command not found  
<program mnemonic> Lookup, failed because query/command type match failed  
Too few or too many program data elements  
E-201  
E-202  
<PROGRAM DATA> value out of range  
<PROGRAM DATA> will not convert to valid type  
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Error Messages  
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6
Error Code Explanation  
E-203  
E-205  
E-207  
E-209  
E-210  
E-211  
E-213  
E-214  
Security violation, command is not available without clearance  
<PROGRAM DATA> is not a Boolean value or word  
<PROGRAM DATA> will not convert to an unsigned 16-bit value  
<PROGRAM DATA> will not convert to an unsigned 32-bit value  
<PROGRAM DATA> will not convert to a floating point value  
<PROGRAM DATA> will not convert to a character value  
<PROGRAM DATA> is incorrect block data length  
<PROGRAM DATA> length exceeds maximum  
E-302  
Query error; device was addressed to talk, but GPIB controller failed to read all of the  
<RESPONSE MESSAGE>  
E-501  
E-503  
E-504  
E-505  
E-507  
E-510  
E-511  
E-512  
E-513  
E-515  
E-516  
E-519  
LASER interlock disabled output  
LASER open circuit disabled output  
LASER current limit disabled output  
LASER voltage limit disabled output  
LASER power limit disabled output  
LASER out of tolerance disabled output  
LASER control error disabled output  
Analog section status is all 1’s or all 0’s (power down)  
Serial EEPROM checksum error  
Laser output must be off to change ranges  
Incorrect configuration for calibration sequence to start  
Setting a measurement is only valid during the calibration phase for that measurement;  
user has tried to calibrate a measurement without first entering the required calibration  
mode.  
102  
LDX-3232  
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