Important Information
Warranty
The NI PXI-5620 and the NI PXI-5621 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.
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For patents covering National Instruments products, refer to the appropriate location: Help»Patents in your software, the patents.txt file
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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 Web site 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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About This Manual
Chapter 1
Taking Measurements with the NI PXI-562x
Configuring and Testing the Digitizer...........................................................................1-2
Acquiring Data Programmatically.................................................................................1-3
Chapter 2
How the NI 562x Works ................................................................................................2-1
Digitizing the Signal—The ADC....................................................................2-3
Incorporating the DDC....................................................................................2-4
Block Diagram ..............................................................................................................2-5
Other Features................................................................................................................2-6
Triggering........................................................................................................2-7
Calibration .....................................................................................................................2-7
Synchronizing Multiple PXI Devices............................................................................2-8
Appendix A
Technical Support and Professional Services
Glossary
Index
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About This Manual
The NI PXI-562x is a single-channel high-speed digitizer module whose
dynamic range and resolution are optimized for frequency-domain analysis
applications in research, product design and validation, and manufacturing
test. This manual provides information on installing, connecting signals to,
and acquiring data from the NI PXI-562x. This manual also provides an
overview of the features, functionality, and use of the NI PXI-562x
high-speed digitizer module.
Conventions
The following conventions are used in this manual:
<>
Angle brackets that contain numbers separated by an ellipsis represent a
range of values associated with a bit or signal name—for example,
DBIO<3..0>.
»
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 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.
This font is also used for the proper names of disk drives, paths, directories,
programs, subprograms, subroutines, device names, functions, operations,
variables, filenames and extensions, and code excerpts.
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About This Manual
Related Documentation
The following documents contain information that you might find helpful
as you read this manual:
•
•
•
•
NI PXI-5620 Specifications
NI PXI-5621 Specifications
NI-SCOPE User Manual
Spectral Measurements Toolset User Guide
NI PXI-562x User Manual
x
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1
Taking Measurements
with the NI PXI-562x
The NI PXI-5620 is a 64 Ms/s, 14-bit frequency-domain digitizer
module optimized for the best possible noise and distortion performance
in a 5–25 MHz passband. It has a –3 dB front-end bandwidth from
10 kHz to 36 MHz, and is always AC-coupled, meaning it does not admit
DC components of a signal.
The NI PXI-5621 is a DC-coupled version of the NI PXI-5620, optimized
for a passband of 0–25 MHz. Except for its permanent DC coupling and
wider front-end bandwidth, the NI PXI-5621 is functionally identical to the
NI PXI-5620.
Refer to the NI PXI-5620 Specifications and the NI PXI-5621
Specifications documents for NI PXI-562x performance specifications.
This chapter provides information on installing, connecting signals to,
and acquiring data from the NI 562x modules.
The NI 562x family of high-speed digitizers has the following features:
•
•
A 14-bit, 64 MS/s analog-to-digital converter (ADC)
32 or 64 MB deep onboard sample memory
Installing the Software and Hardware
Perform the following steps to set up your digitizer:
1. If you are using an application development environment (ADE) or
third-party tool, install it now if you have not already done so. The
supported ADEs include LabVIEW, LabWindows/CVI, and other C or
C++ environments.
Note You must install all of the included software before installing your hardware.
2. Install NI-SCOPE. The included NI-SCOPE CD contains the software
you need to configure, test, and program operation of the NI 562x.
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Chapter 1
Taking Measurements with the NI PXI-562x
a. Insert your NI-SCOPE CD into your CD drive. If installation does
not start automatically, navigate to your CD drive and click
setup.exe.
b. To install both the instrument driver and ADE examples, select the
Programmatic and Interactive Support option when prompted.
3. Install the Spectral Measurements Toolset (SMT) CD, if included.
The SMT provides frequency-domain functionality and examples.
If installation does not start automatically, navigate to your CD drive
and click setup.exe.
Caution You must turn off and unplug your chassis before installing your device.
To prevent damage due to electrostatic discharge or contamination, handle the device using
the edges or the metal bracket.
4. Install your digitizer as shown in Figure 1-1.
PXI Chassis
O
N
S
T
A
N
D
B
Y
1
2
4
5
6
7
8
Your PXI Device
Ejector Handle in
Down Position
Figure 1-1. PXI Installation
Configuring and Testing the Digitizer
To configure and test your NI 562x, complete the following steps:
1. Launch Measurement & Automation Explorer.
2. Double-click Devices and Interfaces to open a list of recognized
devices.
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Chapter 1
Taking Measurements with the NI PXI-562x
3. Find the NI 562x in the list. Notice the device number assigned to your
NI 562x. You need this device number to program your NI 562x.
4. Right-click the device name, and select Properties from the menu.
5. From the Properties window, click Test Resources to test the device
resources. A dialog box appears and indicates if the resource test has
passed.
6. Click Run Test Panels to run the functional test panels and begin
using your NI 562x. Connect a signal to your digitizer, and select
appropriate parameters.
7. Click Advanced to enable triggering options.
8. Click Close when you finish testing your NI 562x.
9. Click OK in the Properties window.
You have successfully installed and configured the necessary software and
hardware to use your NI 562x.
Acquiring Data Programmatically
You can acquire data programmatically either by writing an application for
your NI 562x or by using one of the examples that ships with NI-SCOPE.
For time-domain examples, go to the following default locations:
•
LabVIEW examples are located in the Functions palette at
Instrument I/O»Instrument Drivers»NI SCOPE»IF Digitizers.
•
Examples for C and Visual Basic programmers using
Windows Me/98/95 are located in vxipnp\win95\niScope\
Examples.
•
•
•
Examples for C programmers using Windows 2000/NT are located at
vxipnp\winnt\niScope\Examples\c.
Examples for Visual Basic programmers using Windows 2000/NT are
located at vxipnp\winnt\niScope\Examples\VisualBasic.
LabWindows/CVI examples are located at
cvi\NI-SCOPE Support\samples\niScope\cvi.
Note If you installed the examples in a different location, your file paths differ from the
default locations above.
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Chapter 1
Taking Measurements with the NI PXI-562x
For more detailed VI and function help, refer to the NI-SCOPE VI
Reference Help and the NI-SCOPE Function Reference Help, located
at Start»Programs»National Instruments»NI-SCOPE.
Safety Information
The following section contains important safety information that you must
follow when installing and using the product.
Do not operate the product in a manner not specified in this document.
Misuse of the product can result in a hazard. You can compromise the
safety protection built into the product if the product is damaged in any
way. If the product is damaged, return it to National Instruments for repair.
Do not substitute parts or modify the product except as described in this
document. Use the product only with the chassis, modules, accessories, and
cables specified in the installation instructions. You must have all covers
and filler panels installed during operation of the product.
Do not operate the product in an explosive atmosphere or where there may
be flammable gases or fumes. Operate the product only at or below the
pollution degree stated in the NI PXI-5620 Specifications and the
NI PXI-5620 Specifications documents. Pollution is foreign matter in a
solid, liquid, or gaseous state that can reduce dielectric strength or surface
resistivity. The following is a description of pollution degrees:
•
Pollution degree 1 means no pollution or only dry, nonconductive
pollution occurs. The pollution has no influence.
•
Pollution degree 2 means that only nonconductive pollution occurs in
most cases. Occasionally, however, a temporary conductivity caused
by condensation must be expected.
•
Pollution degree 3 means that conductive pollution occurs, or dry,
nonconductive pollution occurs that becomes conductive due to
condensation.
Clean the product with a soft nonmetallic brush. Make sure that the product
is completely dry and free from contaminants before returning it to service.
You must insulate signal connections for the maximum voltage for which
the product is rated. Do not exceed the maximum ratings for the product.
Remove power from signal lines before connecting them to or
disconnecting them from the product.
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Chapter 1
Taking Measurements with the NI PXI-562x
Operate this product only at or below the installation category stated in the
NI PXI-5620 Specifications and the NI PXI-5620 Specifications
documents.
The following is a description of installation categories:
•
Installation Category I is for measurements performed on circuits not
directly connected to MAINS1. This category is a signal level such as
voltages on a printed wire board (PWB) on the secondary of an
isolation transformer.
Examples of Installation Category I are measurements on circuits not
derived from MAINS and specially protected (internal)
MAINS-derived circuits.
•
•
Installation Category II is for measurements performed on circuits
directly connected to the low-voltage installation. This category refers
to local-level distribution such as that provided by a standard wall
outlet.
Examples of Installation Category II are measurements on household
appliances, portable tools, and similar equipment.
Installation Category III is for measurements performed in the building
installation. This category is a distribution level referring to hardwired
equipment that does not rely on standard building insulation.
Examples of Installation Category III include measurements on
distribution circuits and circuit breakers. Other examples of
Installation Category III are wiring including cables, bus-bars, junction
boxes, switches, socket outlets in the building/fixed installation, and
equipment for industrial use, such as stationary motors with a
permanent connection to the building/fixed installation.
•
Installation Category IV is for measurements performed at the source
of the low-voltage (<1,000 V) installation.
Examples of Installation Category IV are electric meters, and
measurements on primary overcurrent protection devices and
ripple-control units.
1
MAINS is defined as the electricity supply system to which the equipment concerned is designed to be connected either for
powering the equipment or for measurement purposes.
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Chapter 1
Taking Measurements with the NI PXI-562x
Below is a diagram of a sample installation.
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2
Hardware Overview
This chapter provides an overview of the features and functionality of
the NI 562x.
How the NI 562x Works
1. The signal enters the NI 562x through the analog front panel connector,
INPUT. Refer to the Connecting Signals section to find more about the
front panel.
2. The signal is filtered and conditioned. Gain and dither are applied to
Gain, and AC Coupling section for more information.
Digitizing the Signal—The ADC section for more information.
4. (Optional) The digital downconverter (DDC) digitally zooms in
on data. Refer to the Incorporating the DDC section.
5. The data is sent to onboard memory (the buffer). Refer to the Storing
Data in Memory section for additional information.
6. The data is transferred to the host computer via the PXI backplane.
Analog
Input
P
X
I
Filtering/
Conditioning
DDC
(Optional)
Onboard
Memory
ADC
B
u
s
Figure 2-1. Basic Signal Flow
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Chapter 2
Hardware Overview
Connecting Signals
Figure 2-2 shows the NI 562x front panel, which contains three connectors:
two SMA connectors and an SMB connector.
One of the SMA connectors, INPUT, is for attaching the analog input signal
you want to measure. The second SMA connector, REF CLK IN, is a 50 Ω,
10 MHz, AC-coupled reference input. The SMB connector, PFI1, is for
external digital triggers.
562x
64 MS/s Digitizer
INPUT
50
+20 dBm MAX
REF CLK IN
50
+16 dBm MAX
PFI 1
Figure 2-2. NI 562x Front Panel
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Chapter 2
Hardware Overview
Conditioning the Signal—Impedance, Dither, Gain, and AC Coupling
To minimize distortion, signals receive a minimal amount of conditioning.
Gain and coupling are nonadjustable. The NI PXI-5620 is AC coupled,
meaning it rejects any DC signal components. The NI PXI-5621 is DC
coupled, meaning its wider passband acquires DC signal components also.
Both versions of the NI 562x digitizer module have a set input impedance
of 50 Ω and may apply dither to the input signal.
Input Impedance
The input impedance of the NI 562x and the output impedance of the source
connected to the NI 562x form an impedance divider, which attenuates the
input signal according to the following formula:
Rin
------------------
Vm = Vs ×
Rin + Rs
where Vm is the measured voltage
Vs is the unloaded source voltage
Rin is the input impedance of the NI 562x
Rs is the output impedance of the external device
If the signal you are measuring has an output impedance other than 50 Ω,
your measurements are affected by this impedance divider. For example,
if the device has 75 Ω output impedance, your measured signal has 80%
of the voltage it would have at 50 Ω.
Dither
Dither is random noise added to the input signal between 0 and 5 MHz.
Dither lowers the amount of distortion caused by differential nonlinearity
in the ADC when a signal is digitized. When an FFT is applied to the signal,
this random noise cancels out most of the distortion created by differential
nonlinearity. Dither is not automatically applied, but you can enable it in
software.
Digitizing the Signal—The ADC
Regardless of your requested sample rate, the NI 562x ADC is always
running at 64 MS/s. If you request a rate less than 64 MS/s, the timing
engine of the NI 562x stores only one sample in a group of n samples,
effectively reducing the sample rate to 64/n MS/s.
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Chapter 2
Hardware Overview
Incorporating the DDC
Optionally, you can route the data through the DDC before storing it in
onboard memory.
The DDC is a digital signal processing (DSP) chip, the Intersil
HSP50214B. The first stage uses a digital quadrature mixer that shifts a
signal to baseband from any frequency within the range of the digitizer.
The next stage decimates (reduces the sample rate) by an integer from
4–16,384. A series of programmable digital lowpass filters prior to each
stage of decimation prevents aliasing when the sample rate is reduced. You
can retrieve the decimated data as in-phase and quadrature, or as phase and
magnitude. A discriminator allows you to take the derivative of the phase
to demodulate an FM signal.
By mixing, filtering, and decimating the sampled data, the DDC allows you
to zoom in on a band of frequencies much narrower than the Nyquist band
of the ADC. The lower sample rate means that signals of longer duration
can be stored in the same amount of memory. For spectral analysis, you can
use a smaller, faster FFT to look at only the band passed through the DDC.
Refer to the NI-SCOPE VI Reference Help for specific DDC attributes you
can use to program your NI 562x. For more information on using the
onboard DDC with LabVIEW, refer to the online help included with
NI-SCOPE and the Spectral Measurements Toolset software.
Storing Data in Memory
Samples are acquired into onboard memory on the NI 562x before being
transferred to the host computer. The minimum size for a buffer is
approximately 256 samples although you can specify smaller buffers in
software. When specifying a smaller buffer size, the minimum number
of points are still acquired into onboard memory, but only the specified
number of points are retrieved into the host computer memory.
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 562x 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 limited only by
the amount of onboard memory.
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Chapter 2
Hardware Overview
Block Diagram
The block diagram below illustrates the operation of the NI 562x.
An explanation of some of these features follows.
Digital
Downconverter
Dither
Analog
Input
(INPUT)
Onboard
Memory
Data Path
Logic
MITE
(PXI Interface)
+
Filter
ADC
P
X
I
Voltage
Controlled
Oscillator
Phase
Detector
TIO
PLL
(Timing and Control)
10 MHz
Reference
Input
CalDAC
(REF CLK IN)
CLK 10
Trigger and
Clock Routing
PXI Trigger
External Trigger
EXT TRIG
(PFI)
Figure 2-3. NI 562x Block Diagram
The digital downconverter is a digital signal processor (DSP) that allows
you to digitally zoom in on data, which reduces the amount of data
transferred into memory and speeds up the rate of data transfer. The digital
downconverter performs frequency-translation, filtering, and decimation
after signals go through the ADC. Refer to the Incorporating the DDC
section for more information.
The PLL uses a phase detector to synchronize the acquisition clock to either
a 10 MHz reference clock supplied through REF CLK IN or to the CLK 10
signal from the PXI backplane. You can also leave the acquisition clock in
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Chapter 2
Hardware Overview
a free-running state, in which the acquisition clock is not synchronized to
any external reference.
The voltage controlled crystal oscillator (VCXO) is a 64 MHz clock.
The trigger and clock routing area directs clock signals and triggers.
The TIO is the timing engine used for the NI 562x.
The MITE is the PXI bus interface. The MITE provides high-speed direct
memory access (DMA) transfers from the NI 562x to the host computer
memory.
Other Features
This section contains information on other features on the NI 562x.
Multiple-Record Acquisitions
After the trigger has been received and the posttrigger samples have been
stored, you can configure the NI 562x to begin another acquisition that is
stored in another memory record on the device. This process is a
multiple-record acquisition. To perform multiple-record acquisitions,
configure the NI 562x to the number of records to be acquired before
starting the acquisition. The NI 562x acquires an additional record each
time a trigger is accepted until all the requested records are stored
in memory. After the initial setup, this process does not require software
intervention.
Between each record, a dead time exists during which the trigger is not
accepted. If the record length is greater than 80 µs, the dead time is 500 ns.
If, however, the record length is less than 80 µs, the dead time is 80 µs.
During this time, the memory controller sets up for the next record. Also,
additional dead time may exist while the minimum number of pretrigger
samples are being acquired.
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Chapter 2
Hardware Overview
Figure 2-4 shows a timing diagram of a multiple-record acquisition.
1
2
3
Trigger
500 ns
Acquisition
In Progress
Buffer
1
2
1 = Trigger Not Accepted (Pretrigger Points Not Acquired)
2 = Trigger Not Accepted (500 ns Dead Time)
3 = Trigger Not Accepted (Acquisition in Progress)
= Trigger Accepted
Figure 2-4. Multiple-Record Acquisition Timing Diagram
Triggering
You can externally trigger the NI 562x through the digital line, PFI1.
You can also use software to trigger the NI 562x. Figure 2-5 shows the
different trigger sources. The digital triggers are TTL-level signals with
a minimum pulse-width requirement of 100 ns or 16 ns times the DDC
decimation.
Software
RTSI <0..7>
Trigger
8
PFI1
PXI Star
Figure 2-5. Digital Trigger Sources
Calibration
Although the NI 562x is factory calibrated, it needs periodic calibration to
verify that it is still within the specified accuracy. For more information on
calibration, contact NI or visit the NI Web site at
ni.com/support/calibrat.
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Chapter 2
Hardware Overview
Synchronizing Multiple PXI Devices
The NI 562x uses a PLL to synchronize the 64 MHz sample clock to a
10 MHz reference clock. You can either supply the reference clock through
the SMA connector (REF CLK IN) on the front panel or use the system
reference clock on the PXI backplane.
The PXI bus and the NI 562x have the following timing and triggering
features that you can use for synchronizing multiple digitizers:
•
System Reference Clock—A 10 MHz clock on the PXI backplane
with 100 ppm accuracy. It is independently distributed to each PXI
peripheral slot through equal-length traces with a skew of less than
1 ns between slots. Multiple devices can use this common timebase for
synchronization, which allows each NI 562x to phase lock to the
system reference clock.
•
SMA connector (REF CLK IN)—A 10 MHz reference input that you
can use to connect an external frequency source for synchronization.
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ni.com
A
Technical Support and
Professional Services
Visit the following sections of the National Instruments Web site at
ni.com for technical support and professional services:
•
Support—Online technical support resources include the following:
–
Self-Help Resources—For immediate answers and solutions,
visit our extensive library of technical support resources available
in English, Japanese, and Spanish at ni.com/support. These
resources are available for most products at no cost to registered
users and include software drivers and updates, a KnowledgeBase,
product manuals, step-by-step troubleshooting wizards, hardware
schematics and conformity documentation, example code,
tutorials and application notes, instrument drivers, discussion
forums, a measurement glossary, and so on.
–
Assisted Support Options—Contact NI engineers and other
measurement and automation professionals by visiting
ni.com/ask. Our online system helps you define your question
and connects you to the experts by phone, discussion forum,
or email.
•
•
Training—Visit ni.com/custed for self-paced tutorials, videos, and
interactive CDs. You also can register for instructor-led, hands-on
courses at locations around the world.
System Integration—If you have time constraints, limited in-house
technical resources, or other project challenges, NI Alliance Program
members can help. To learn more, call your local NI office or visit
ni.com/alliance.
If you searched ni.com and could not find the answers you need, contact
your local office or NI corporate headquarters. Phone numbers for our
worldwide offices are listed at the front of this manual. You also can visit
the Worldwide Offices section of ni.com/niglobal to access the branch
office Web sites, which provide up-to-date contact information, support
phone numbers, email addresses, and current events.
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Glossary
Prefix
p-
Meanings
pico
Value
10–12
10–9
10– 6
10–3
103
n-
nano-
micro-
milli-
kilo-
µ-
m-
k-
M-
G-
mega-
giga-
106
109
Symbols
%
+
–
/
percent
positive of, or plus
negative of, or minus
per
°
degree
plus or minus
ohm
Ω
<
less than
A
A
amperes
A/D
AC
analog-to-digital
alternating current
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Glossary
AC coupled
ADC
allowing the transmission of AC signals while blocking DC signals
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 with
16 bits has a higher resolution, and thus a higher degree of accuracy,
than a 12-bit ADC.
ADE
alias
application development environment
a false lower frequency component that appears in sampled data acquired
at too low a sampling rate
amplification
a type of signal conditioning that improves accuracy in the resulting
digitized signal and reduces noise
amplitude flatness
a measure of how close to constant the gain of a circuit remains over a range
of frequencies
analog bandwidth
attenuate
the range of frequencies to which a measuring device can respond
to decrease the amplitude of a signal
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.
bus
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. An example of the PC bus is the PCI bus.
C
C
Celsius
CMOS
complementary metal oxide semiconductor—a process used in making
chips.
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Glossary
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)
coupling
the manner in which a signal is connected from one location to another
D
data path logic
a signal router
dB
decibel—the unit for expressing a logarithmic measure of the ratio of two
signal levels: dB = 20log10 V1/V2, for signals in volts
dBm
decibels with reference to 1 mW, the standard unit of power level used in
RF and microwave work. Using this standard, 0 dBm equals 1 mW, 10 dBm
equals 10 mW, and so on. In a 50 Ω system, 0 dBm equals 0.224 Vrms
.
DC
direct current
DDC
See digital downconverter.
dead time
default setting
a period of time in which no activity can occur
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.
differential input
digital downconverter
dither
an analog input consisting of two terminals, both of which are isolated from
computer ground, whose difference is measured
a DSP that selects only a narrow portion of the frequency spectrum, thereby
eliminating unwanted data before it is transferred into memory
random noise added to a signal before it is digitized to minimize distortion
created by differential nonlinearity
DMA
direct memory access—a method by which data is transferred to/from
computer memory from/to a device or memory on the bus while the
processor does something else. DMA is the fastest method of transferring
data to/from computer memory.
double insulated
a device that contains the necessary insulating structures to provide electric
shock protection without the requirement of a safety ground connection
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Glossary
drivers
DSP
software that controls a specific hardware instrument
digital signal processor
E
EEPROM
electrically erasable programmable read-only memory—ROM that can be
erased with an electrical signal and reprogrammed
F
FFT
fast Fourier transform
filtering
a type of signal conditioning that allows you to remove unwanted signals or
frequency components from the signal you are trying to measure
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—the number of scans read or updates written 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
impedance
in.
resistance
inch or inches
inductance
the relationship of induced voltage to current
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Glossary
input bias current
input impedance
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
interrupt level
ISA
the relative priority at which a device can interrupt
industry standard architecture
L
LabVIEW
Laboratory Virtual Instrument Engineering Workbench—a program
development application based on the programming language G and used
commonly for test and measurement purposes
LSB
least significant bit
M
m
meters
M
(1) Mega, the standard metric prefix for 1 million or 106, when used with
units of measure such as volts and hertz; (2) mega, the prefix for 1,048,576,
or 220, when used with B to quantify data or computer memory
MB
megabytes of memory
MITE
MXI Interface to Everything—a custom ASIC designed by NI that
implements the PCI bus interface. The MITE supports bus mastering for
high-speed data transfers over the PCI bus.
multiple-record
acquisition
multiple, distinct chunks (or records) of data
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Glossary
N
noise
an undesirable electrical signal—noise comes from external sources such as
the AC power line, motors, generators, transformers, fluorescent lights,
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.
O
Ohm’s Law
onboard memory
overcurrent
overrange
(R = V/I)—the relationship of voltage to current in a resistance
the device memory. Onboard memory is distinct from computer memory.
amperages above the maximum power level specified for a device
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.
P
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
PFI
the absolute maximum or minimum amplitude of a signal (AC + DC)
Programmable Function Input
PLL
phase-locked loop—an electronic circuit that controls an oscillator so that
it maintains a constant phase angle relative to a reference signal
PXI
PCI eXtensions for Instrumentation—PXI is an open specification that
builds on the CompactPCI specification by adding instrumentation-specific
features
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Glossary
R
R
resistor
RAM
random-access memory
random interleaved
sampling (RIS)
method of increasing sample rate by repetitively sampling a repeated
waveform
real-time sampling
record length
sampling that occurs immediately
the size of a chunk (or record) of data that can be or has been acquired by a
device
resolution
The smallest amount of input signal change that an instrument or sensor can
detect. Resolution can be expressed in bits, in proportions, or in percent
of full scale. For example, a system has 12-bit resolution, one part in
4,096 resolution, and 0.0244% of full scale.
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
S
s
seconds
samples
S
S/s
samples per second—used to express the rate at which an instrument
samples an analog signal
sample rate
sense
the speed that a device can acquire data
in 4-wire resistance the sense measures the voltage across the resistor
being excited by the excitation current
settling time
the amount of time required for a voltage to reach its final value within
specified limits
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Glossary
Shannon Sampling
Theorem
a theorem stating that a signal must be sampled at least twice as fast as the
bandwidth of the signal to accurately reconstruct the signal as a waveform
source impedance
system noise
T
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)
a measure of the amount of noise seen by an analog circuit or an ADC when
the analog inputs are grounded
temperature
coefficient
the percentage that a measurement will vary according to temperature.
See also thermal drift.
thermal drift
measurements that change as the temperature varies
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.
TIO
timing input/output—the engine used for timing and control.
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
TTL
any event that causes or starts some form of data capture
transistor-transistor logic—a digital circuit composed of bipolar transistors
wired in a certain manner
V
V
volts
VAC
VDC
volts alternating current
volts direct current
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Glossary
Verror
voltage error
vertical sensitivity
VI
the smallest voltage change a device can detect
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
dead time, in multiple-record acquisitions, 2-6
diagnostic resources, A-1
digitizing the signal (ADC), 2-3
dither, 2-3
A
acquiring data
multi-record acquisitions, 2-6
programmatically, 1-3
ADC, 2-3
documentation
conventions used in manual, ix
online library, A-1
related documentation, x
B
basic signal flow (figure), 2-1
instrument, A-1
C
software, A-1
calibration, 2-7
conditioning signals
AC coupling, 2-3
example code, A-1
dither, 2-3
gain, 2-3
input impedance, 2-3
connecting signals, 2-2
contacting National Instruments, A-1
conventions used in the manual, ix
coupling, 2-3
frequently asked questions, A-1
front panel (figure), 2-2
customer
G
education, A-1
professional services, A-1
technical support, A-1
gain, 2-3
hardware installation, 1-1
hardware overview
basic signal flow (figure), 2-1
block diagram, 2-5
calibration, 2-7
D
data acquisition
multi-record acquisitions, 1-3, 2-6
programmatically, 1-3
data, storing in memory, 2-4
DDC (digital downconverter)
incorporating, 2-4
conditioning signals
coupling, 2-3
dither, 2-3
overview, 2-4
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Index
help
I
gain, 2-3
input impedence, 2-3
O
online technical support, A-1
technical support, A-1
phase detector, 2-5
phase-locked loop (PLL), 2-5
phone technical support, A-1
professional services, A-1
programmatically acquiring data, 1-3
programming examples, A-1
PXI devices, multiple, synchronizing, 2-8
PXI installation, 1-1
incorporating DDC, 2-4
input impedence, 2-3
installing software and hardware, 1-1
instrument drivers, A-1
K
REF CLK IN connector, 2-2, 2-8
M
MITE interface, 2-6
multiple-record acquisitions
S
safety information, 1-4
timing diagram (figure), 2-7
coupling, 2-3
dither, 2-3
gain, 2-3
N
National Instruments
input impedance, 2-3
computer, 2-1
SMA connectors, 2-2, 2-8
software drivers, A-1
software installation, 1-1
support
customer education, A-1
professional services, A-1
system integration services, A-1
technical support, A-1
worldwide offices, A-1
NI PXI-562x digitizer
See also hardware overview
acquiring data programmatically, 1-3
block diagram, 2-5
front panel (figure), 2-2
installing software and hardware, 1-1
safety information, 1-4
technical, A-1
synchronizing multiple PXI devices, 2-8
system integration services, A-1
System Reference Clock, PXI, 2-8
NI-SCOPE driver, 1-1
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Index
T
technical support, A-1
telephone technical support, A-1
TIO (timing engine), 2-6
training
voltage controlled crystal oscillator
(VCXO), 2-6
Web
customer, A-1
trigger and clock routing area, 2-6
triggering
professional services, A-1
technical support, A-1
worldwide technical support, A-1
digital trigger sources (figure), 2-7
overview, 2-7
troubleshooting resources, A-1
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