Important Information
Warranty
The NI 5911 is warranted against defects in materials and workmanship for a period of one year from the date of shipment, as evidenced by
receipts or other documentation. National Instruments will, at its option, repair or replace equipment that proves to be defective during the
warranty period. This warranty includes parts and labor.
The media on which you receive National Instruments software are warranted not to fail to execute programming instructions, due to defects
in materials and workmanship, for a period of 90 days from date of shipment, as evidenced by receipts or other documentation. National
Instruments will, at its option, repair or replace software media that do not execute programming instructions if National Instruments receives
notice of such defects during the warranty period. National Instruments does not warrant that the operation of the software shall be
uninterrupted or error free.
A Return Material Authorization (RMA) number must be obtained from the factory and clearly marked on the outside of the package before
any equipment will be accepted for warranty work. National Instruments will pay the shipping costs of returning to the owner parts which are
covered by warranty.
National Instruments believes that the information in this document is accurate. The document has been carefully reviewed for technical
accuracy. In the event that technical or typographical errors exist, National Instruments reserves the right to make changes to subsequent
editions of this document without prior notice to holders of this edition. The reader should consult National Instruments if errors are suspected.
In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it.
EXCEPT AS SPECIFIED HEREIN, NATIONAL INSTRUMENTS MAKES NO WARRANTIES, EXPRESS OR IMPLIED, AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF
MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. CUSTOMER’S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF
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DAMAGES RESULTING FROM LOSS OF DATA, PROFITS, USE OF PRODUCTS, OR INCIDENTAL OR CONSEQUENTIAL DAMAGES, EVEN IF ADVISED OF THE POSSIBILITY
THEREOF. This limitation of the liability of National Instruments will apply regardless of the form of action, whether in contract or tort, including
negligence. Any action against National Instruments must be brought within one year after the cause of action accrues. National Instruments
shall not be liable for any delay in performance due to causes beyond its reasonable control. The warranty provided herein does not cover
damages, defects, malfunctions, or service failures caused by owner’s failure to follow the National Instruments installation, operation, or
maintenance instructions; owner’s modification of the product; owner’s abuse, misuse, or negligent acts; and power failure or surges, fire,
flood, accident, actions of third parties, or other events outside reasonable control.
Copyright
Under the copyright laws, this publication may not be reproduced or transmitted in any form, electronic or mechanical, including photocopying,
recording, storing in an information retrieval system, or translating, in whole or in part, without the prior written consent of National
Instruments Corporation.
Trademarks
CVI™, FLEX ADC™, LabVIEW™, National Instruments™, NI™, and ni.com™ are trademarks of National Instruments Corporation.
Product and company names mentioned herein are trademarks or trade names of their respective companies.
WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS
(1) NATIONAL INSTRUMENTS PRODUCTS ARE NOT DESIGNED WITH COMPONENTS AND TESTING FOR A LEVEL OF
RELIABILITY SUITABLE FOR USE IN OR IN CONNECTION WITH SURGICAL IMPLANTS OR AS CRITICAL COMPONENTS IN
ANY LIFE SUPPORT SYSTEMS WHOSE FAILURE TO PERFORM CAN REASONABLY BE EXPECTED TO CAUSE SIGNIFICANT
INJURY TO A HUMAN.
(2) IN ANY APPLICATION, INCLUDING THE ABOVE, RELIABILITY OF OPERATION OF THE SOFTWARE PRODUCTS CAN BE
IMPAIRED BY ADVERSE FACTORS, INCLUDING BUT NOT LIMITED TO FLUCTUATIONS IN ELECTRICAL POWER SUPPLY,
COMPUTER HARDWARE MALFUNCTIONS, COMPUTER OPERATING SYSTEM SOFTWARE FITNESS, FITNESS OF COMPILERS
AND DEVELOPMENT SOFTWARE USED TO DEVELOP AN APPLICATION, INSTALLATION ERRORS, SOFTWARE AND
HARDWARE COMPATIBILITY PROBLEMS, MALFUNCTIONS OR FAILURES OF ELECTRONIC MONITORING OR CONTROL
DEVICES, TRANSIENT FAILURES OF ELECTRONIC SYSTEMS (HARDWARE AND/OR SOFTWARE), UNANTICIPATED USES OR
MISUSES, OR ERRORS ON THE PART OF THE USER OR APPLICATIONS DESIGNER (ADVERSE FACTORS SUCH AS THESE ARE
HEREAFTER COLLECTIVELY TERMED “SYSTEM FAILURES”). ANY APPLICATION WHERE A SYSTEM FAILURE WOULD
CREATE A RISK OF HARM TO PROPERTY OR PERSONS (INCLUDING THE RISK OF BODILY INJURY AND DEATH) SHOULD
NOT BE RELIANT SOLELY UPON ONE FORM OF ELECTRONIC SYSTEM DUE TO THE RISK OF SYSTEM FAILURE. TO AVOID
DAMAGE, INJURY, OR DEATH, THE USER OR APPLICATION DESIGNER MUST TAKE REASONABLY PRUDENT STEPS TO
PROTECT AGAINST SYSTEM FAILURES, INCLUDING BUT NOT LIMITED TO BACK-UP OR SHUT DOWN MECHANISMS.
BECAUSE EACH END-USER SYSTEM IS CUSTOMIZED AND DIFFERS FROM NATIONAL INSTRUMENTS' TESTING
PLATFORMS AND BECAUSE A USER OR APPLICATION DESIGNER MAY USE NATIONAL INSTRUMENTS PRODUCTS IN
COMBINATION WITH OTHER PRODUCTS IN A MANNER NOT EVALUATED OR CONTEMPLATED BY NATIONAL
INSTRUMENTS, THE USER OR APPLICATION DESIGNER IS ULTIMATELY RESPONSIBLE FOR VERIFYING AND VALIDATING
THE SUITABILITY OF NATIONAL INSTRUMENTS PRODUCTS WHENEVER NATIONAL INSTRUMENTS PRODUCTS ARE
INCORPORATED IN A SYSTEM OR APPLICATION, INCLUDING, WITHOUT LIMITATION, THE APPROPRIATE DESIGN,
PROCESS AND SAFETY LEVEL OF SUCH SYSTEM OR APPLICATION.
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Compliance
FCC/Canada Radio Frequency Interference Compliance*
Determining FCC Class
The Federal Communications Commission (FCC) has rules to protect wireless communications from interference. The FCC
places digital electronics into two classes. These classes are known as Class A (for use in industrial-commercial locations only)
or Class B (for use in residential or commercial locations). Depending on where it is operated, this product could be subject to
restrictions in the FCC rules. (In Canada, the Department of Communications (DOC), of Industry Canada, regulates wireless
interference in much the same way.)
Digital electronics emit weak signals during normal operation that can affect radio, television, or other wireless products. By
examining the product you purchased, you can determine the FCC Class and therefore which of the two FCC/DOC Warnings
apply in the following sections. (Some products may not be labeled at all for FCC; if so, the reader should then assume these are
Class A devices.)
FCC Class A products only display a simple warning statement of one paragraph in length regarding interference and undesired
operation. Most of our products are FCC Class A. The FCC rules have restrictions regarding the locations where FCC Class A
products can be operated.
FCC Class B products display either a FCC ID code, starting with the letters EXN,
or the FCC Class B compliance mark that appears as shown here on the right.
FCC/DOC Warnings
This equipment generates and uses radio frequency energy and, if not installed and used in strict accordance with the instructions
in this manual and the CE Mark Declaration of Conformity**, may cause interference to radio and television reception.
Classification requirements are the same for the Federal Communications Commission (FCC) and the Canadian Department
of Communications (DOC).
Changes or modifications not expressly approved by National Instruments could void the user’s authority to operate the
equipment under the FCC Rules.
Class A
Federal Communications Commission
This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC
Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated
in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and
used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this
equipment in a residential area is likely to cause harmful interference in which case the user will be required to correct
the interference at his own expense.
Canadian Department of Communications
This Class A digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations.
Cet appareil numérique de la classe A respecte toutes les exigences du Règlement sur le matériel brouilleur du Canada.
Class B
Federal Communications Commission
This equipment has been tested and found to comply with the limits for a Class B digital device, pursuant to part 15 of the
FCC Rules. These limits are designed to provide reasonable protection against harmful interference in a residential installation.
This equipment generates, uses and can radiate radio frequency energy and, if not installed and used in accordance with the
instructions, may cause harmful interference to radio communications. However, there is no guarantee that interference will not
occur in a particular installation. If this equipment does cause harmful interference to radio or television reception, which can
be determined by turning the equipment off and on, the user is encouraged to try to correct the interference by one or more of
the following measures:
•
•
•
•
Reorient or relocate the receiving antenna.
Increase the separation between the equipment and receiver.
Connect the equipment into an outlet on a circuit different from that to which the receiver is connected.
Consult the dealer or an experienced radio/TV technician for help.
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Canadian Department of Communications
This Class B digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations.
Cet appareil numérique de la classe B respecte toutes les exigences du Règlement sur le matériel brouilleur du Canada.
Compliance to EU Directives
Readers in the European Union (EU) must refer to the Manufacturer's Declaration of Conformity (DoC) for information**
pertaining to the CE Mark compliance scheme. The Manufacturer includes a DoC for most every hardware product except for
those bought for OEMs, if also available from an original manufacturer that also markets in the EU, or where compliance is not
required as for electrically benign apparatus or cables.
To obtain the DoC for this product, click Declaration of Conformity at ni.com/hardref.nsf/. This website lists the DoCs
by product family. Select the appropriate product family, followed by your product, and a link to the DoC appears in Adobe
Acrobat format. Click the Acrobat icon to download or read the DoC.
*
Certain exemptions may apply in the USA, see FCC Rules §15.103 Exempted devices, and §15.105(c). Also available in
sections of CFR 47.
** The CE Mark Declaration of Conformity will contain important supplementary information and instructions for the user or
installer.
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Conventions
The following conventions are used in this manual:
»
The » symbol leads you through nested menu items and dialog box options
to a final action. The sequence File»Page Setup»Options directs you to
pull down the File menu, select the Page Setup item, and select Options
from the last dialog box.
This icon denotes a note, which alerts you to important information.
This icon denotes a caution, which advises you of precautions to take to
avoid injury, data loss, or a system crash.
bold
Bold text denotes items that you must select or click on in the software,
such as menu items and dialog box options. Bold text also denotes
parameter names.
italic
Italic text denotes variables, emphasis, a cross reference, or an introduction
to a key concept. This font also denotes text that is a placeholder for a word
or value that you must supply.
monospace
Text in this font denotes text or characters that you should enter from the
keyboard, sections of code, programming examples, and syntax examples.
Text in this font is also used for proper names of functions or variables.
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Chapter 1
Installing the NI 5911 ....................................................................................................1-1
Acquiring Data with Your NI 5911 ...............................................................................1-3
Chapter 2
Differential Input.............................................................................................2-2
Input Impedance..............................................................................................2-3
Oscilloscope Mode..........................................................................................2-5
When Internal Calibration Is Needed..............................................................2-7
Triggering and Arming ..................................................................................................2-8
Analog Trigger Circuit ....................................................................................2-9
Trigger Hold-Off .............................................................................................2-10
Memory..........................................................................................................................2-10
Triggering and Memory Usage .......................................................................2-10
Multiple-Record Acquisitions........................................................................................2-11
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Contents
RTSI Bus and Clock PFI............................................................................................... 2-11
PFI Lines......................................................................................................... 2-11
PFI Lines as Inputs ........................................................................... 2-12
PFI Lines as Outputs......................................................................... 2-12
Synchronization .............................................................................................. 2-12
Appendix A
Appendix B
Technical Support Resources
Glossary
Index
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1
Taking Measurements
with the NI 5911
Thank you for buying a National Instruments (NI) 5911 digitizer, featuring
the FLEX ADC. This chapter provides information on installing,
connecting signals to, and acquiring data from your NI 5911.
Installing the NI 5911
There are two main steps involved in installation:
1. Install the NI-SCOPE driver software. You use this driver to write
programs to control your NI 5911 in different application development
interactively control your NI 5911 with the Scope Soft Front Panel.
2. Install your NI 5911. For step-by-step instructions for installing
NI-SCOPE and the NI 5911, see Where to Start with Your NI Digitizer.
in Appendix A, Specifications, of this manual.
Connecting Signals
Figure 1-1 shows the front panel for the NI 5911. The front panel contains
three connectors—a BNC connector, an SMB connector, and a 9-pin mini
circular DIN connector (see Figure 1-2).
The BNC connector is for attaching the analog input signal you wish to
measure. The BNC connector is analog input channel 0. To minimize noise,
do not allow the shell of the BNC cable to touch or lie near the metal of the
computer chassis. The SMB connector is for external triggers and for
generating a probe compensation signal. The SMB connector is PFI1.
The DIN connector gives you access to an additional external trigger line.
The DIN connector can be used to access PFI2.
Note The +5 V signal is fused at 1.1 A. However, NI recommends limiting the current
from this pin to 30 mA. The fuse is self-resetting.
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Chapter 1
Taking Measurements with the NI 5911
CH0
PFI1
PFI2
(DIN)
Figure 1-1. NI 5911 Connectors
9
8
7
6
5
2
4
1
3
1
3
+5 Volts (Fused)
GND
Reserved
4
5
6
Reserved
Reserved
PFI 2
7
8
9
Reserved
Reserved
Reserved
Figure 1-2. 9-Pin Mini Circular DIN Connector
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Chapter 1
Taking Measurements with the NI 5911
Acquiring Data with Your NI 5911
You can acquire data either programmatically—by writing an application
for your NI 5911—or interactively with the Scope Soft Front Panel.
Programmatically Controlling Your NI 5911
To help you get started programming your NI 5911, NI-SCOPE comes
with examples that you can use or modify.
You can find examples for these different ADEs:
•
•
•
LabVIEW—Go to Program Files\National Instruments\
LabVIEW\Examples\Instr\niScopeExamples\
LabWindows/CVI, C, and Visual Basic with Windows 98/95—Go to
vxipnp\win95\Niscope\Examples\c\
LabWindows/CVI, C, and Visual Basic with Windows 2000/NT—Go
to vxipnp\winnt\Niscope\Examples\
For information about using NI-SCOPE to programmatically control your
digitizer, refer to your NI-SCOPE Software User Manual. Other resources
include the NI-SCOPE Instrument Driver Quick Reference Guide. It
contains abbreviated information on the most commonly used functions
and LabVIEW VIs. For more detailed function reference help, see the
NI-SCOPE Function Reference Help file, located at Start»Programs»
National Instruments»NI-SCOPE. For more detailed VI help,
use LabVIEW context-sensitive help (Help»Show Context Help) or the
NI-SCOPE VI Reference Help, located at Start»Programs»National
Instruments»NI-SCOPE.
Interactively Controlling Your NI 5911 with the Scope Soft Front Panel
The Scope Soft Front Panel allows you to interactively control your
NI 5911 as you would a desktop oscilloscope. To launch the Scope Soft
Front Panel select Start»Programs»National Instruments»NI-SCOPE»
NI-SCOPE Soft Front Panel. Refer to the Scope Soft Front Panel Help
file for instructions on configuring the Scope Soft Front Panel for your
specific application.
Note Press F1 with the Scope Soft Front Panel running to access the Scope Soft Front
Panel Help.
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2
Hardware Overview
This chapter includes an overview of the NI 5911, explains the operation of
each functional unit making up your NI 5911, and describes the signal
connections. Figure 2-1 shows a block diagram of the NI 5911.
Analog Input
Connector
AC/DC Coupling
Protect/
Calibration
Mux
PGIA
A/D Converter
100 MHz, 8-Bit
Noise
Shaper
Calibration
Generator
Timing IO/
Memory Control
Reference
Clock
Digital IO
Connector
Digital Signal
Processor
Capture
Memory
Data
Figure 2-1. NI 5911 Block Diagram
Differential Programmable Gain Input Amplifier (PGIA)
The analog input of the NI 5911 is equipped with a differential
programmable gain input amplifier. The PGIA accurately interfaces to and
scales the signal presented to the analog-to-digital converter (ADC)
regardless of source impedance, source amplitude, DC biasing, or
common-mode noise voltages.
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Differential Input
When measuring high dynamic range signals, ground noise is often a
problem. The PGIA of the NI 5911 allows you to make noise-free signal
measurements. The PGIA differential amplifier efficiently rejects any
noise present on the ground signal. Internal to the PGIA, the signal
presented at the negative input is subtracted from the signal presented at the
positive input. As shown in Figure 2-2, this subtraction removes ground
noise from the signal. The inner conductor of the BNC is V+; the outer shell
is V–.
Input Signal
V+
+
Vout
PGIA
–
V–
Ground Noise
Figure 2-2. Noise-Free Measurements of Signal
Grounding Considerations
The path for the positive signal has been optimized for speed and linearity.
You should always apply signals to the positive input and ground to the
negative input. Reversing the inputs will result in higher distortion and
lower bandwidth.
The negative input of the amplifier is grounded to PC ground through a
10 kΩ resistor. The PGIA is therefore referenced to ground, so it is not
necessary to make any external ground connections. If the device you
connect to the NI 5911 is already connected to ground, ground-loop noise
voltages may be induced into your system. Notice that in most of these
situations, the 10 kΩ resistance to PC ground is normally much higher than
the cable impedances you use. As a result, most of the noise voltage occurs
at the negative input of the PGIA where it is rejected, rather than in the
positive input, where it would be amplified.
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Chapter 2
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Input Ranges
To optimize the ADC resolution, you can select different gains for the
PGIA. In this way, you can scale your input signal to match the full input
range of the converter. The NI 5911 PGIA offers seven different input
ranges, from 0.1 V to 10 V, as shown in Table 2-1.
Table 2-1. Input Ranges for the NI 5911
Range
10 V
5 V
Input Protection Threshold
10 V
5 V
5 V
5 V
5 V
5 V
5 V
2 V
1 V
0.5 V
0.2 V
0.1 V
Note If you try to acquire a signal below the set input range the sensitive front-end
components of the NI 5911 may become unstable and begin returning invalid data. To
return the digitizer to a stable configuration, switch to the maximum input range setting and
acquire an AC-coupled or 0 V signal.
Input Impedance
The input impedance of the NI 5911 PGIA is 1 MΩ between the positive
and negative input, 2% depending on input capacitance. The output
impedance of the device connected to the NI 5911 and the input impedance
of the NI 5911 form an impedance divider, which attenuates the input
signal according to the following formula:
VsRin
Vm = -------------------
Rs + Rin
where Vm is the measured voltage, Vs is the source voltage, Rs is the external
source impedance, and Rin is the input impedance.
If the device you are measuring has a very large output impedance, your
measurements will be affected by this impedance divider. For example,
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Chapter 2
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if the device has 1 MΩ output impedance, your measured signal will be
one-half the actual signal value.
Input Bias
The inputs of the PGIA typically draw an input bias current of 1 nA at
25 °C. Attaching a device with a very high source impedance can cause
an offset voltage to be added to the signal you measure, according to
the formula Rs × 1 nA, where Rs is the external source impedance. For
example, if the device you have attached to the NI 5911 has an output
impedance of 10 kΩ, typically the offset voltage is 10 µV (10 kΩ ×1 nA).
Input Protection
The NI 5911 features input-protection circuits that protect both the positive
and negative analog input from damage from AC and DC signals up to
42 V.
If the voltage at one of these inputs exceeds a threshold voltage, Vtr, the
input clamps to Vtr and a resistance of 100 kΩ is inserted in the path to
minimize input currents to a nonharmful level.
The protection voltage, Vtr,is input range dependent, as shown in Table 2-1.
AC Coupling
When you need to measure a small AC signal on top of a large DC
component, you can use AC coupling. AC coupling rejects any
DC component in your signal before it enters into the PGIA. Activating
AC coupling inserts a capacitor in series with the input impedance. Input
coupling can be selected via software. See the Digitizer Basics appendix in
your NI-SCOPE Software User Manual for more information on input
coupling.
Oscilloscope and Flexible Resolution Modes
In oscilloscope mode, the NI 5911 works as a conventional desktop
oscilloscope, acquiring data at 100 MS/s with a vertical resolution of 8 bits.
This mode is useful for displaying waveforms and for deriving waveform
parameters such as slew rate, rise time, and settling time.
Flexible resolution differs from oscilloscope mode in two ways: it has
higher resolution (sampling rate dependent), and the signal bandwidth is
limited to provide antialiasing protection. This mode is useful for spectral
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analysis, distortion analysis, and other measurements for which high
resolution is crucial.
Oscilloscope Mode
The ADC converts at a constant rate of 100 MS/s, but you can choose to
store only a fraction of these samples into memory at a lower rate. This
allows you to store waveforms using fewer data points and decreases the
burden of storing, analyzing, and displaying the waveforms. If you need
faster sampling rates, you can use Random Interleaved Sampling (RIS) to
effectively increase the sampling rate to 1 GS/s for repetitive waveforms.
In oscilloscope mode, all signals up to 100 MHz are passed to the ADC.
You need to ensure that your signal is band-limited to prevent aliasing.
Aliasing and other sampling terms are described more thoroughly in your
NI-SCOPE Software User Manual.
Sampling Methods—Real-Time and RIS
There are two sampling methods available in oscilloscope mode, real-time
and random interleaved sampling (RIS). Using real-time sampling, you can
acquire data at a rate of 100/n MS/s, where n is a number from 1 to 232.
sampling rate above 100 MS/s. In RIS mode, you can sample at rates of
100 MS/s × n, where n is a number from 2 to 10.
Flexible Resolution Mode
Table 2-2 shows the relationship between the available sampling rates,
resolution, and the corresponding bandwidth for flexible resolution mode.
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Table 2-2. Available Sampling Rates and Corresponding Bandwidth
in Flexible Resolution Mode
Sampling Rate
12.5 MS/s
5 MS/s
Resolution
11 Bits
Bandwidth
3.75 MHz
2 MHz
14 Bits
2.5 MS/s
1 MS/s
15.5 Bits
17.5 Bits
18 Bits
1 MHz
400 kHz
200 kHz
80 kHz
40 kHz
20 kHz
8 kHz
500 kS/s
200 kS/s
100 kS/s
50 kS/s
18.5 Bits
19 Bits
19.5 Bits
20.5 Bits
21 Bits
20 kS/s
10 kS/s
4 kHz
Like any other type of converter that uses noise shaping to enhance
resolution, the frequency response of the converter is only flat to its
maximum useful bandwidth. The NI 5911 has a bandwidth of 4 MHz.
Beyond this frequency, there is a span where the converter acts resonant
and where a signal is amplified before being converted. These signals are
attenuated in the subsequent digital filter to prevent aliasing. However,
if the applied signal contains major signal components in this frequency
range, such as harmonics or noise, the converter may overload and signal
data will be invalid. In this case, you will receive an overload warning. You
must then either select a higher input range or attenuate the signal.
How Flexible Resolution Works
The ADC can be sourced through a noise shaping circuit that moves
quantization noise on the output of the ADC from lower frequencies to
higher frequencies. A digital lowpass filter applied to the data removes all
but a fraction of the original shaped quantization noise. The signal is then
resampled to a lower sampling frequency and a higher resolution. Flexible
resolution provides antialiasing protection due to the digital lowpass filter.
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Calibration
The NI 5911 can be calibrated for very high accuracy and resolution due
to an advanced calibration scheme. There are two different types of
calibration: internal, or self, calibration and external calibration. A third
option, internal restore, restores factory settings and should be used only in
the event of a self-calibration failure.
Internal calibration is performed via a software command that
compensates for drifts caused by environmental temperature changes. You
can internally calibrate your NI 5911 without any external equipment
connected. External calibration recalibrates the device when the specified
calibration interval has expired. See Appendix A, Specifications, for the
calibration interval. External calibration requires you to connect an external
precision voltage reference to the device.
Internally Calibrating the NI 5911
Internally calibrate your NI 5911 with a software function or a
LabVIEW VI. See Chapter 3, Common Functions and Examples, of your
NI-SCOPE Software User Manual for step-by-step instructions for
calibrating your digitizer.
When Internal Calibration Is Needed
To provide the maximum accuracy independent of temperature changes,
the NI 5911 contains a heater that stabilizes the temperature of the most
sensitive circuitries on the board. However, the heater can accommodate
for temperature changes over a fixed range of 5 °C. When temperatures
exceed this range, the heater no longer is able to stabilize the temperature,
and signal data becomes inaccurate. When the temperature range has been
exceeded, you receive a warning, and you need to perform an internal
calibration.
What Internal Calibration Does
Internal calibration performs the following operations:
•
The heater is set to regulate over a range of temperatures centered at
the current environmental temperature. The circuit components require
a certain amount of time to stabilize at the new temperature. This
temperature stabilization accounts for the majority of the calibration
time.
•
Gain and offset are calibrated for each individual input range.
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•
•
The linearity of the ADC is calibrated using an internal sinewave
generator as reference.
The time-to-digital converter used for RIS measurements is calibrated.
Caution Do not apply high-amplitude or high-frequency signals to the NI 5911 during
internal calibration. For optimal calibration performance, disconnect the input signal from
the NI 5911.
Why Errors Occur During Acquisition
The NI 5911 uses a heater circuit to maintain constant temperature on the
critical circuitry used in flexible resolution mode. If this circuit is unable to
maintain the temperature within specification, an error is generated. This
error indicates that the temperature of the ADC is out of range and should
be recalibrated by performing an internal calibration. During acquisition in
flexible resolution mode, an error will be generated if the input to the ADC
goes out of range for the converter. The fact that this condition has occurred
may not be obvious from inspecting the data due to the digital filtering that
takes place on the acquired data. Therefore, an error occurs to let you know
that the data includes some samples that were out of the range of the
converter and may be inaccurate.
External Calibration
External calibration calibrates the internal reference on the NI 5911.
The NI 5911 is already calibrated when it is shipped from the factory.
Periodically, the NI 5911 will need external calibration to remain within
the specified accuracy. For more information on calibration, contact NI, or
visit ni.com/calibration. For actual intervals and accuracy, refer to
Appendix A, Specifications.
Triggering and Arming
There are several triggering methods for the NI 5911. The trigger can be an
analog level that is compared to the input or any of several digital inputs.
You can also call a software function to trigger the board. Figure 2-3 shows
the different trigger sources. When you use a digital signal, that signal must
be at a high TTL level for at least 40 ns before any triggers will be accepted.
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High
Level
+
Analog
Input
COMP
Gain
Analog
Trigger
Circuit
ATC_OUT
COMP
Low
Level
–
a. Analog Trigger Circuit
Software
ATC_OUT
RTSI <0..6>
Trigger
Arm
7
2
PFI1, PFI2
b. Trigger and Arm Sources
Figure 2-3. Trigger Sources
Analog Trigger Circuit
The analog trigger on the NI 5911 operates by comparing the current
analog input to an onboard threshold voltage. This threshold voltage is the
trigger value, and can be set within the current input range in 170 steps.
This means that for a 10 V input range, the trigger can be set in increments
of 20 V/170 = 118 mV. There may also be a hysteresis value associated
with the trigger that can be set in the same size increments. The hysteresis
value creates a trigger window the signal must pass through before the
trigger is accepted. You can generate triggers on a rising or falling edge
condition. For a more complete discussion of triggering, see Chapter 3,
Common Functions and Examples, of your NI-SCOPE Software User
Manual.
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Trigger Hold-Off
Trigger hold-off is the minimum length of time (in seconds) from an
accepted trigger to the start of the next record. In other words, when a
trigger is accepted, the trigger counter is loaded with the desired hold-off
time. After completing its current record, the digitizer records no data and
accepts no triggers until the hold-off counter runs out. When the counter
runs out, the next record begins and a trigger may be accepted. Setting a
hold-off time shorter than posttrigger acquisition time has no effect, as
triggers are always rejected during an acquisition.
Note Time to acquire posttrigger samples is (posttrigger samples)/(sample rate
(megahertz)).
Trigger hold-off is provided in hardware using a 32-bit counter clocked
by a 25 MHz internal timebase. With this configuration, you can select
a hardware hold-off value of 40 ns to 171.8 s in increments of 40 ns. For
more information regarding trigger hold-off, see the Common Trigger
Parameters section in Chapter 3, Common Functions and Examples, of
your NI-SCOPE Software User Manual.
Memory
The NI 5911 allocates at least 4 kB of onboard memory for every
acquisition. Samples are stored in this buffer before transfer to the host
computer. Thus the minimum size for a buffer in the onboard memory is
approximately 4,000 8-bit oscilloscope mode samples or 1,000 32-bit
flexible resolution mode samples. Software allows you to specify buffers
of less than these minimum sizes. However, the minimum number of points
are still acquired into onboard memory, but only the specified number of
points are transferred into the memory of the host computer.
The total number of samples that can be stored depends on the size of the
acquisition memory module installed on the NI 5911 and the size of each
acquired sample.
Triggering and Memory Usage
During the acquisition, samples are stored in a circular buffer that is
continually rewritten until a trigger is received. After the trigger is
received, the NI 5911 continues to acquire posttrigger samples if you have
specified a posttrigger sample count. The acquired samples are placed into
onboard memory. The number of posttrigger or pretrigger samples is only
limited by the amount of onboard memory.
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Multiple-Record Acquisitions
After the trigger has been received and the posttrigger samples have been
stored, the NI 5911 can be configured to begin another acquisition that is
stored in another onboard memory record. This is a multiple-record
acquisition. To perform multiple-record acquisitions, configure the
NI 5911 to the number of records you want to acquire before starting the
acquisition. The NI 5911 acquires an additional record each time a trigger
is accepted until all the requested records are stored in memory. You may
acquire up to 1024 records if your NI 5911 is equipped with 4 MB of
onboard memory, or 4096 records with 16 MB. Software intervention after
the initial setup is not required.
Multiple-record acquisitions can quickly acquire numerous triggered
waveforms because they allow hardware rearming of the digitizer before
the data is fetched. Therefore the dead time, or the time when the digitizer
is not ready for a trigger, is extremely small.
For more information on multiple-record acquisitions and dead time, see
the Making a Multiple-Record Acquisition section in Chapter 5, Tasks and
Examples, of your NI-SCOPE Software User Manual.
RTSI Bus and Clock PFI
The RTSI bus allows NI digitizers to synchronize timing and triggering on
multiple devices. The RTSI bus has seven bidirectional trigger lines and
one bidirectional clock signal.
You can program any of the seven trigger lines to provide or accept a
synchronous trigger signal. You can also use any of the RTSI trigger lines
to provide a synchronization pulse from a master device if you are
synchronizing multiple NI 5911s.
You can use the RTSI bus clock line to provide or accept a 10 MHz
reference clock to synchronize multiple NI 5911 devices.
PFI Lines
The NI 5911 has two digital lines that can accept a trigger, accept or
generate a reference clock, or output a 1 kHz square wave. The function of
each PFI line is independent. However, only one trigger source can be
accepted during acquisition.
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PFI Lines as Inputs
You can select PFI1 or PFI2 as inputs for a trigger or a reference clock.
Please see the Synchronization section below for more information about
the use of reference clocks in the NI 5911.
PFI Lines as Outputs
You can select PFI1 or PFI2 to output several digital signals.
Reference Clock is a 10 MHz clock that is synchronous to the 100 MHz
sample clock on the NI 5911. You can use the reference clock to
synchronize to another NI 5911 configured as a slave device or to other
equipment that can accept a 10 MHz reference.
Frequency Output is a 1 kHz digital pulse train signal with a 50% duty
cycle. The most common application of Frequency Output for the NI 5911
is to provide a signal for compensating a passive probe.
Synchronization
The NI 5911 uses a digital phase locked loop to synchronize the 100 MHz
sample clock to a 10 MHz reference. This reference frequency can be
supplied by an internal crystal oscillator or through an external frequency
input through the RTSI bus clock line or a PFI input.
The NI 5911 may also output its 10 MHz reference on the RTSI bus clock
line or a PFI line so that other NI 5911s or other equipment can be
synchronized to the same reference.
While the reference clock input is sufficient to synchronize the 100 MHz
sample clocks, it is also necessary to synchronize clock dividers on each
NI 5911 so that internal clock divisors are synchronized on each different
device. These lower frequencies are important because they are used to
determine trigger times and sample position.
To synchronize the NI 5911 clock dividers, you must connect the digitizers
with an NI RTSI bus cable. One of the RTSI bus triggers must be
designated as a synchronization line. This line will be an output from the
master device and an input on the slave device. To synchronize the
digitizers, a single pulse is sent from the master NI 5911 to the slaves. This
pulse supplies the slave devices with a reference time to clear their clock
dividers. Hardware arming cannot be used during an acquisition using
multiple devices. For more information about synchronization, refer to
your NI-SCOPE Software User Manual.
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A
Specifications
This appendix lists the specifications of the NI 5911. These specifications
Bandwidth.............................................. 100 MHz maximum,
see Table 2-2, Available
Sampling Rates and
Corresponding Bandwidth in
Flexible Resolution Mode
Number of channels ............................... 1
Number of flexible resolution ADC....... 1
Max sample rate..................................... 1 GS/s repetitive,
100 MS/s single shot
Resolution
Sample Rate
100/n* MS/s
Mode
Effective Resolution
8 Bits
Oscilloscope
12.5 MS/s
5 MS/s
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
11 Bits
14 Bits
2.5 MS/s
1 MS/s
15.5 Bits
17.5 Bits
18 Bits
500 kS/s
200 kS/s
100 kS/s
50 kS/s
18.5 Bits
19 Bits
19.5 Bits
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Appendix A
Specifications
Sample Rate
20 kS/s
Mode
Effective Resolution
20.5 Bits
Flexible Resolution
Flexible Resolution
10 kS/s
21 Bits
* 1<n<232 in oscilloscope mode
Sample onboard memory........................4 MB or 16 MB
Memory sample depth
Sampling
Frequency
Sample Depth
(4 MB)
Sample Depth
(16 MB)
Mode
100/n* MS/s Oscilloscope
4 MS
1 MS
1 MS
1 MS
1 MS
1 MS
1 MS
1 MS
1 MS
1 MS
1 MS
16 MS
4 MS
4 MS
4 MS
4 MS
4 MS
4 MS
4 MS
4 MS
4 MS
4 MS
12.5 MS/s
5 MS/s
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
Flexible Resolution
2.5 MS/s
1 MS/s
500 kS/s
200 kS/s
100 kS/s
50 kS/s
20 kS/s
10 kS/s
* 1<n<232 in oscilloscope mode
Vertical sensitivity (input ranges)
Input Range
Noise Referred to Input
10 V
5 V
2 V
1 V
174 dBfs/ Hz
168 dBfs/ Hz
160 dBfs/ Hz
154 dBfs/ Hz
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Specifications
Input Range
Noise Referred to Input
0.5 V
0.2 V
0.1 V
148 dBfs/ Hz
140 dBfs/ Hz
134 dBfs/ Hz
Acquisition Characteristics
Accuracy
DC gain accuracy................................... 0.05% signal 0.0001% fs
for all input ranges at 1 MS/s in
flexible resolution mode
DC offset accuracy................................. 0.1 mV 0.01% fs
for all input ranges at 1 MS/s in
flexible resolution mode
Input coupling ........................................ DC and AC, software selectable
AC coupling cut-off frequency
(–3 dB) ................................................... 2.3 Hz 13%
Input impedance..................................... 1 MΩ 2%
Max measurable input voltage ............... 10 V (DC + peak AC)
Input protection...................................... 42 VDC (DC + peak AC)
Input bias current ................................... 1 nA, typical at 25 °C
Common-Mode Characteristics
Impedance to chassis ground ................. 10 kΩ
Common-mode rejection ratio ............... CMRR > –70 dB, (Fin < 1 kHz)
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Appendix A
Specifications
Filtering
Sampling
Filter
Mode
Alias
Attenuation
Frequency
100/n* MS/s
12.5 MS/s
Bandwidth
100 MHz
Ripple
3 dB
Oscilloscope
N/A
Flexible
3.75 MHz
0.2 dB
–60 dB
Resolution
5 MS/s
2.5 MS/s
1 MS/s
Flexible
Resolution
2 MHz
1 MHz
400 kHz
200 kHz
80 kHz
40 kHz
20 kHz
8 kHz
0.1 dB
–70 dB
–80 dB
–80 dB
–80 dB
–80 dB
–80 dB
–80 dB
–80 dB
–80 dB
Flexible
Resolution
0.05 dB
Flexible
Resolution
0.005 dB
0.005 dB
0.005 dB
0.005 dB
0.005 dB
0.005 dB
0.005 dB
500 kS/s
200 kS/s
100 kS/s
50 kS/s
20 kS/s
10 kS/s
Flexible
Resolution
Flexible
Resolution
Flexible
Resolution
Flexible
Resolution
Flexible
Resolution
Flexible
4 kHz
Resolution
* 1<n<232 in oscilloscope mode
Dynamic Range
Noise (excluding input-referred noise)
Sampling Frequency
Bandwidth
Noise Density
Total Noise
100 MHz
3.75 MHz
2 MHz
–120 dBfs/ Hz
–135 dBfs/ Hz
–150 dBfs/ Hz
–155 dBfs/ Hz
–43 dBfs
–64 dBfs
–83 dBfs
–91 dBfs
100/n* MS/s
12.5 MS/s
5 MS/s
1 MHz
2.5 MS/s
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Appendix A
Specifications
Sampling Frequency
Bandwidth
Noise Density
Total Noise
400 kHz
200 kHz
80 kHz
40 kHz
20 kHz
8 kHz
–160 dBfs/ Hz
–160 dBfs/ Hz
–160 dBfs/ Hz
–160 dBfs/ Hz
–160 dBfs/ Hz
–160 dBfs/ Hz
–160 dBfs/ Hz
–104 dBfs
–107 dBfs
–111 dBfs
–114 dBfs
–117 dBfs
–121 dBfs
–124 dBfs
1 MS/s
500 kS/s
200 kS/s
100 kS/s
50 kS/s
20 kS/s
4 kHz
10 kS/s
* 1<n<232 in oscilloscope mode
Distortion
SFDR for input
0 dBfs
SFDR for input
SFDR for input
–60 dBfs (typical)
Sampling Frequency
100 MS/s
12.5 MS/s
5 MS/s
–20 dBfs
50 dB
65 dB
50 dB
N/A
85 dB
125 dB
130 dB
135 dB
145 dB
150 dB
160 dB
160 dB
160 dB
160 dB
160 dB
70 dB
90 dB
2.5 MS/s
1 MS/s
75 dB
95 dB
85 dB
105 dB
110 dB
110 dB
110 dB
110 dB
110 dB
110 dB
500 kS/s
200 kS/s
100 kS/s
50 kS/s
90 dB
100 dB
100 dB
100 dB
100 dB
100 dB
20 kS/s
10 kS/s
Timebase System
Reference clock...................................... 10 MHz
Clock accuracy (as master) .................... 10 MHz 50 ppm
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Appendix A
Specifications
Clock input tolerance (as slave)..............10 MHz 100 ppm
Clock jitter ..............................................<75 pSrms, independent of
reference clock source
Clock compatibility ...............................TTL for both input and output
Interpolator resolution
(repetitive only) ......................................1 ns
Sampling clock frequencies
Oscilloscope mode...........................100 MHz/n, where 1<n<232
Flexible resolution mode.................100 MHz/n, where n = 8; 20; 50;
100; 200; 500; 1,000; 2,000;
5,000; 10,000
Reference clock sources .........................PFI lines, RTSI clock, or onboard
Phase difference between
multiple instruments ...............................<5 ns, at any input frequency
<100 MHz, from input connector
to input connector
Triggering Systems
Modes .....................................................Above threshold, below
threshold, between thresholds,
outside thresholds
Source .....................................................CH0, RTSI<0..6>, PFI 1,2
Slope .......................................................Rising/falling
Hysteresis................................................Full-scale voltage/n, where n is
between 1 and 170; full-scale
voltage on TRIG is fixed to 5 V
(without external attenuation)
Coupling .................................................AC/DC on CH0, TRIG
Pretrigger depth ......................................1 to 16 million samples
Posttrigger depth.....................................1 to 16 million samples
Holdoff time ...........................................5 µs – 171.85 s in increments
of 40 ns
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Appendix A
Specifications
Sensitivity............................................... 170 steps in full-scale voltage
range
TRIG input range ................................... 5 V (without external
attenuation)
TRIG input impedance........................... 1 MΩ 1% in parallel
with 30 pF 15 pF
TRIG input protection............................ 42 V [(DC + peak AC) < 10 kHz,
without external attenuation]
Acquisition Modes
RIS ......................................................... 1 GS/s down to 200 MS/s
effective sample rate, repetitive
signals only. Data is interleaved
in software.
RIS accuracy .......................................... <0.5 ns
Single-shot ............................................. 100 MS/s down to 10 kS/s sample
rate for transient and repetitive
signals
Power Requirements
+5 VDC ................................................. 4 A
+12 VDC................................................ 100 mA
–12 VDC ............................................... 100 mA
Physical
Dimensions............................................. 33.8 by 9.9 cm
(13.3 by 3.9 in)
I/O connectors
Analog input CH0........................... BNC female
Digital triggers ................................ SMB female, 9-pin mini DIN
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Appendix A
Specifications
Operating Environment
Note Multiple NI 5911s in the same computer may raise operating temperatures beyond
specification and give rise to imprecise data. NI strongly recommends leaving an empty
PCI slot between multiple NI 5911s or adding a fan.
Ambient temperature ..............................5 to 40 °C
Relative humidity ...................................10% to 90%, noncondensing
Storage Environment
Ambient temperature ..............................–20 to 65 °C
EMC Compliance
Calibration
CE2001, FCC
Internal....................................................Internal calibration is done upon
software command. The
calibration involves gain, offset
and linearity correction for all
input ranges and input modes.
Interval.............................................1 week, or any time temperature
changes beyond 5 °C. Hardware
detects temperature variations
beyond calibration limits, which
can also be queried by software.
External...................................................Internal reference requires
recalibration
Interval.............................................1 year
Warm-up time.........................................1 minute
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B
Technical Support Resources
Web Support
National Instruments Web support is your first stop for help in solving
installation, configuration, and application problems and questions. Online
problem-solving and diagnostic resources include frequently asked
questions, knowledge bases, product-specific troubleshooting wizards,
manuals, drivers, software updates, and more. Web support is available
through the Technical Support section of ni.com.
NI Developer Zone
The NI Developer Zone at ni.com/zoneis the essential resource for
building measurement and automation systems. At the NI Developer Zone,
you can easily access the latest example programs, system configurators,
tutorials, technical news, as well as a community of developers ready to
share their own techniques.
Customer Education
National Instruments provides a number of alternatives to satisfy your
training needs, from self-paced tutorials, videos, and interactive CDs to
instructor-led hands-on courses at locations around the world. Visit the
Customer Education section of ni.comfor online course schedules,
syllabi, training centers, and class registration.
System Integration
If you have time constraints, limited in-house technical resources, or other
dilemmas, you may prefer to employ consulting or system integration
services. You can rely on the expertise available through our worldwide
network of Alliance Program members. To find out more about our
Alliance system integration solutions, visit the System Integration section
of ni.com.
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Appendix B
Technical Support Resources
Worldwide Support
National Instruments has offices located around the world to help address
your support needs. You can access our branch office Web sites from the
Worldwide Offices section of ni.com. Branch office Web sites provide
up-to-date contact information, support phone numbers, e-mail addresses,
and current events.
If you have searched the technical support resources on our Web site and
still cannot find the answers you need, contact your local office or National
Instruments corporate. Phone numbers for our worldwide offices are listed
at the front of this manual.
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Glossary
Prefix
p-
Meanings
pico-
Value
10–12
10–9
10– 6
10–3
103
n-
nano-
micro-
milli-
µ-
m-
k-
kilo-
M-
G-
mega-
giga-
106
109
Symbols
%
+
–
/
percent
positive of, or plus
negative of, or minus
per
°
degree
plus or minus
ohm
Ω
A
A
amperes
A/D
AC
analog to digital
alternating current
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Glossary
AC coupled
ADC
the passing of a signal through a filter network that removes the
DC component of the signal
analog-to-digital converter—an electronic device, often an integrated
circuit, that converts an analog voltage to a digital number
ADC resolution
the resolution of the ADC, which is measured in bits. An ADC with16 bits
has a higher resolution, and thus a higher degree of accuracy, than a 12-bit
ADC.
alias
a false lower frequency component that appears in sampled data acquired
at too low a sampling rate
amplification
amplitude flatness
attenuate
a type of signal conditioning that improves accuracy in the resulting
digitized signal and reduces noise
a measure of how close to constant the gain of a circuit remains over a range
of frequencies
to reduce in magnitude
B
b
bit—one binary digit, either 0 or 1
B
byte—eight related bits of data, an eight-bit binary number. Also used
to denote the amount of memory required to store one byte of data.
bandwidth
the range of frequencies present in a signal, or the range of frequencies to
which a measuring device can respond
buffer
bus
temporary storage for acquired or generated data (software)
the group of conductors that interconnect individual circuitry in a computer.
Typically, a bus is the expansion vehicle to which I/O or other devices are
connected. Examples of PC buses are the PCI and ISA bus.
C
C
Celsius
channel
pin or wire lead to which you apply or from which you read the analog or
digital signal
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Glossary
clock
hardware component that controls timing for reading from or writing to
groups
CMRR
common-mode rejection ratio—a measure of an instrument’s ability to
reject interference from a common-mode signal, usually expressed in
decibels (dB)
counter/timer
coupling
a circuit that counts external pulses or clock pulses (timing)
the manner in which a signal is connected from one location to another
D
dB
decibel—the unit for expressing a logarithmic measure of the ratio of
two signal levels: dB=20log10 V1/V2, for signals in volts
DC
direct current
default setting
a default parameter value recorded in the driver. In many cases, the default
input of a control is a certain value (often 0) that means use the current
default setting.
device
a plug-in data acquisition board, card, or pad. The NI 5911 is an example
of a device.
differential input
double insulated
drivers
an analog input consisting of two terminals, both of which are isolated from
computer ground, whose difference is measured
a device that contains the necessary insulating structures to provide electric
shock protection without the requirement of a safety ground connection
software that controls a specific hardware instrument
E
EEPROM
electrically erasable programmable read-only memory—ROM that can be
erased with an electrical signal and reprogrammed
equivalent time
sampling
any method used to sample signals in such a way that the apparent sampling
rate is higher than the real sampling rate
event
the condition or state of an analog or digital signal
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Glossary
F
filtering
a type of signal conditioning that allows you to filter unwanted signals from
the signal you are trying to measure
fs
full-scale—total voltage in the input range. A 10 V input range is 20 V fs
G
gain
the factor by which a signal is amplified, sometimes expressed in decibels
H
hardware
the physical components of a computer system, such as the circuit boards,
plug-in boards, chassis, enclosures, peripherals, cables, and so on
harmonics
Hz
multiples of the fundamental frequency of a signal
hertz—per second, as in cycles per second or samples per second
I
I/O
input/output—the transfer of data to/from a computer system involving
communications channels, operator interface devices, and/or data
acquisition and control interfaces
in.
inches
inductance
input bias current
input impedance
the relationship of induced voltage to current
the current that flows into the inputs of a circuit
the measured resistance and capacitance between the input terminals of a
circuit
instrument driver
interrupt
a set of high-level software functions that controls a specific plug-in DAQ
board. Instrument drivers are available in several forms, ranging from a
function callable language to a virtual instrument (VI) in LabVIEW.
a computer signal indicating that the CPU should suspend its current task
to service a designated activity
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Glossary
interrupt level
ISA
the relative priority at which a device can interrupt
industry standard architecture
K
k
kilo—the standard metric prefix for 1,000, or 103, used with units of
measure such as volts, hertz, and meters
kS
1,000 samples
L
LabVIEW
laboratory virtual instrument engineering workbench—a graphical
programming ADE developed by National Instruments
LSB
least significant bit
M
m
meters
MB
megabytes of memory
see buffer
memory buffer
MS
million samples
most significant bit
MSB
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Glossary
N
noise
soldering irons, CRT displays, computers, electrical storms, welders, radio
transmitters, and internal sources such as semiconductors, resistors, and
capacitors. Noise corrupts signals you are trying to send or receive.
Nyquist frequency
a frequency that is one-half the sampling rate. See also Nyquist Sampling
Theorem.
Nyquist Sampling
Theorem
the theorem states that if a continuous bandwidth-limited analog signal
contains no frequency components higher than half the frequency at which
it is sampled, then the original signal can be recovered without distortion.
O
Ohm’s Law
(R=V/I)—the relationship of voltage to current in a resistance
overrange
a segment of the input range of an instrument outside of the normal
measuring range. Measurements can still be made, usually with a
degradation in specifications.
oversampling
sampling at a rate greater than the Nyquist frequency
P
passband
the frequency range that a filter passes without attenuation
PCI
Peripheral Component Interconnect—a high-performance expansion bus
architecture originally developed by Intel to replace ISA and EISA; it is
achieving widespread acceptance as a standard for PCs and workstations
and offers a theoretical maximum transfer rate of 132 Mbytes/s
peak value
the absolute maximum or minimum amplitude of a signal (AC + DC)
posttriggering
the technique to acquire a programmed number of samples after trigger
conditions are met
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Glossary
pretriggering
PXI
the technique used on a device to keep a buffer filled with data, so that when
the trigger conditions are met, the sample includes the data leading up
to the trigger condition
PCI eXtensions for Instrumentation. PXI is an open specification that
builds off the CompactPCI specification by adding
instrumentation-specific features.
R
R
resistor
RAM
random-access memory
sampling that occurs immediately
real-time sampling
random interleaved
sampling
method of increasing the sample rate by repetitively sampling a repeated
waveform
resolution
the smallest signal increment that can be detected by a measurement
system. Resolution can be expressed in bits or in digits. The number of bits
in a system is roughly equal to 3.3 times the number of digits.
rms
root mean square—a measure of signal amplitude; the square root of the
average value of the square of the instantaneous signal amplitude
ROM
read-only memory
RTSI bus
real-time system integration bus—the National Instruments timing bus that
connects devices directly, by means of connectors on top of the boards, for
precise synchronization of functions
S
s
seconds
samples
S
S/s
samples per second—used to express the rate at which an instrument
samples an analog signal. 100 MS/s would equal 100 million samples each
second.
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Glossary
sense
in four-wire resistance the sense measures the voltage across the resistor
being excited by the excitation current
settling time
source impedance
the amount of time required for a voltage to reach its final value within
specified limits
a parameter of signal sources that reflects current-driving ability of voltage
sources (lower is better) and the voltage-driving ability of current sources
(higher is better)
system noise
a measure of the amount of noise seen by an analog circuit or an ADC when
the analog inputs are grounded
T
temperature
coefficient
the percentage that a measurement will vary according to temperature.
See also thermal drift
thermal drift
thermal EMFs
thermal electromotive forces—voltages generated at the junctions of
dissimilar metals that are functions of temperature. Also called
thermoelectric potentials.
thermoelectric
potentials
see thermal EMFs
transfer rate
the rate, measured in bytes/s, at which data is moved from source to
destination after software initialization and set up operations; the maximum
rate at which the hardware can operate
trigger
any event that causes or starts some form of data capture
U
undersampling
sampling at a rate lower than the Nyquist frequency—can cause aliasing
the number of output updates per second
update rate
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Glossary
V
V
volts
VAC
VDC
Verror
VI
volts alternating current
volts direct current
voltage error
virtual instrument—(1) a combination of hardware and/or software
elements, typically used with a PC, that has the functionality of a classic
stand-alone instrument (2) a LabVIEW software module (VI), which
consists of a front panel user interface and a block diagram program
Vrms
volts, root mean square value
W
waveform shape
the shape the magnitude of a signal creates over time
working voltage
the highest voltage that should be applied to a product in normal use,
normally well under the breakdown voltage for safety margin
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Index
customer education, B-1
A
AC coupling, 2-4
accuracy characteristics, A-3
acquisition
multiple record, 2-11
(PGIA)
Scope Soft Front Panel, 1-3
acquisition characteristics specifications
accuracy, A-3
common-mode characteristics, A-3
distortion, A-5
dynamic range, A-4
AC coupling, 2-4
differential input, 2-2
input bias, 2-4
input impedance, 2-3
input protection, 2-4
input ranges, 2-3
filtering, A-4
acquisition modes specifications, A-7
acquisition system specifications, A-1
analog trigger circuit, 2-9
noise-free signal measurement (figure), 2-2
DIN connector, 1-1
distortion specifications, A-5
dynamic range specifications, A-4
B
bias, input, 2-4
block diagram of NI 5911, 2-1
BNC connector, 1-1
EMC compliance, A-8
C
calibration
errors occurring during acquisition, 2-8
external calibration, 2-8
internal calibration, 2-7
specifications, A-8
flexible resolution mode
clock lines, 2-12
common-mode characteristics, A-3
connectors
available sampling rates (table), 2-6
definition, 2-5
memory sample depth (table), A-2
purpose and use, 2-6
BNC connector, 1-1
DIN connector, 1-1
location on front panel (figure), 1-2
SMB connector, 1-1
sampling rate specifications (table), A-1
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Index
input protection circuits, 2-4
input ranges, 2-3
installing NI 5911, 1-1
G
grounding considerations, 2-2
H
hardware overview
memory
See also specifications
acquisition system
description, 2-10
triggering and memory usage, 2-10
PFI lines, 2-11
block diagram of NI 5911, 2-1
calibration, 2-7
amplifier (PGIA)
National Instruments Web support, B-1
NI 5911
AC coupling, 2-4
See also hardware overview
block diagram, 2-1
connectors
differential input, 2-2
input bias, 2-4
input ranges, 2-3
(figure), 2-2
BNC connector, 1-1
DIN connector, 1-1
location on front panel (figure), 1-2
SMB connector, 1-1
front panel (figure), 1-2
installing, 1-1
Scope Soft Front Panel, 1-3
specifications
flexible resolution mode, 2-5
memory, 2-10
multiple record acquisition, 2-11
oscilloscope mode, 2-5
RTSI bus trigger and clock lines, 2-11
trigger hold-off, 2-10
triggering and arming
analog trigger circuit, 2-9
acquisition characteristics, A-3
acquisition modes, A-7
acquisition system, A-1
triggering systems, A-6
NI Developer Zone, B-1
NI-SCOPE driver software
installing, 1-1
programmatically controlling
NI 5911, 1-3
noise-free measurements, 2-2
I
impedance
input and output impedance, 2-3
input bias, 2-4
input impedance, 2-3
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acquisition characteristics
accuracy, A-3
O
operating environment specifications, A-8
oscilloscope mode
common-mode characteristics, A-3
distortion, A-5
dynamic range, A-4
definition, 2-4
purpose and use, 2-5
Real-Time and RIS sampling
methods, 2-5
filtering, A-4
acquisition modes, A-7
acquisition system, A-1
calibration, A-8
output impedance, 2-3
P
EMC compliance, A-8
operating environment, A-8
physical, A-7
PFI lines
as inputs, 2-12
power requirements, A-7
storage environment, A-8
timebase system, A-5
triggering systems, A-6
storage environment specifications, A-8
synchronization, 2-12
system integration, by National Instruments,
as outputs, 2-12
overview, 2-11
PGIA. See differential programmable gain
input amplifier (PGIA)
physical specifications, A-7
power requirement specifications, A-7
programmable gain input amplifier PGIA. See
differential programmable gain input
amplifier (PGIA)
programmatically controlling NI 5911, 1-3
technical support resources, B-1
timebase system specifications, A-5
triggering and arming
R
Random Interleaved Sampling (RIS), 2-5
real-time sampling, 2-5
analog trigger circuit, 2-9
memory usage, 2-10
RIS (Random Interleaved Sampling), 2-5
RTSI bus trigger and clock lines
PIF lines, 2-11
trigger hold-off, 2-10
purpose and use, 2-11
trigger sources (figure), 2-9
S
vertical sensitivity specifications, A-2
sampling methods—real-time and RIS, 2-5
sampling rate, flexible resolution mode
(table), 2-6
W
Web support from National Instruments, B-1
worldwide technical support, B-2
Scope Soft Front Panel, 1-3
SMB connector, 1-1
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