National Instruments | NI 785xR | User's Manual | National Instruments NI 785xR User's Manual

Intelligent DAQ
NI R Series Intelligent DAQ User Manual
NI 781xR, 783xR, NI 784xR, and NI 785xR Devices
R Series Intelligent DAQ User Manual
June 2008
370489F-01
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Contents
About This Manual
Conventions ...................................................................................................................vii
Related Documentation..................................................................................................viii
Reconfigurable I/O Documentation ................................................................viii
Additional Resources.......................................................................................x
Chapter 1
Introduction
About the Reconfigurable I/O Device ...........................................................................1-1
Using PXI with CompactPCI.........................................................................................1-2
Overview of Reconfigurable I/O ...................................................................................1-3
Reconfigurable I/O Concept............................................................................1-3
Flexible Functionality .......................................................................1-4
User-Defined I/O Resources .............................................................1-4
Device-Embedded Logic and Processing .........................................1-4
Reconfigurable I/O Architecture .....................................................................1-5
Reconfigurable I/O Applications.....................................................................1-6
Software Development ..................................................................................................1-6
LabVIEW FPGA Module................................................................................1-6
LabVIEW Real-Time Module.........................................................................1-7
Cables and Accessories..................................................................................................1-8
Custom Cabling .............................................................................................................1-9
Safety Information .........................................................................................................1-9
Chapter 2
Hardware Overview of the NI 78xxR
NI 7811R Overview.......................................................................................................2-3
NI 7813R Overview.......................................................................................................2-3
NI 7830R Overview.......................................................................................................2-3
NI 7831R/7833R Overview ...........................................................................................2-4
NI 784xR Overview.......................................................................................................2-4
NI 785xR Overview.......................................................................................................2-4
Analog Input (Multifunction R Series Only) .................................................................2-4
Input Modes.....................................................................................................2-5
Input Range .....................................................................................................2-5
Connecting Analog Input Signals ..................................................................................2-6
© National Instruments Corporation
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Contents
Types of Signal Sources ................................................................................................ 2-8
Floating Signal Sources .................................................................................. 2-8
Ground-Referenced Signal Sources ................................................................ 2-8
Input Modes................................................................................................................... 2-8
Differential Connection Considerations (DIFF Input Mode) ......................... 2-10
Differential Connections for Ground-Referenced Signal Sources ... 2-11
Differential Connections for Nonreferenced or
Floating Signal Sources ................................................................. 2-12
Single-Ended Connection Considerations ...................................................... 2-13
Single-Ended Connections for Floating Signal Sources
(RSE Input Mode).......................................................................... 2-14
Single-Ended Connections for Grounded Signal Sources
(NRSE Input Mode)....................................................................... 2-15
Common-Mode Signal Rejection Considerations........................................... 2-16
Analog Output ............................................................................................................... 2-16
Connecting Analog Output Signals ............................................................................... 2-17
Digital I/O...................................................................................................................... 2-17
Connecting Digital I/O Signals ..................................................................................... 2-17
RTSI Trigger Bus .......................................................................................................... 2-21
PXI Local Bus (NI PXI-781xR/783xR Only) ............................................................... 2-21
Switch Settings (NI 781xR/783xR Only)...................................................................... 2-23
+5 V Power Source........................................................................................................ 2-28
Device Fuse Replacement (NI 784xR/785xR Only) ...................................... 2-29
Field Wiring Considerations (NI 783xR/784xR/785xR Only) ..................................... 2-31
Chapter 3
Calibration (NI 783xR/784xR/785xR Only)
Loading Calibration Constants ...................................................................................... 3-1
Internal Calibration........................................................................................................ 3-1
External Calibration....................................................................................................... 3-2
Appendix A
Connecting I/O Signals
Appendix B
Using the SCB-68 Shielded Connector Block
Appendix C
Technical Support and Professional Services
Glossary
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ni.com
About This Manual
This manual describes the electrical and mechanical aspects of the
National Instruments 781xR/783xR/784xR/785xR devices and contains
information about programming and using the devices.
Conventions
The following conventions appear 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,
AO <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. When this symbol is marked on a
product, refer to the Safety Information section of Chapter 1, Introduction,
for information about precautions to take.
When symbol is marked on a product, it denotes a warning advising you to
take precautions to avoid electrical shock.
When symbol is marked on a product, it denotes a component that may be
hot. Touching this component may result in bodily injury.
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. Italic text also denotes text that is a placeholder for a word
or value that you must supply.
© National Instruments Corporation
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R Series Intelligent DAQ User Manual
About This Manual
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.
Multifunction R Series
Multifunction R Series refers to the NI 783xR, NI 784xR, and NI 785xR,
which provide both analog and digital I/O.
NI 78xxR
NI 781xR, 783xR, NI 784xR, and NI 785xR refer to all PXI and PCI
R Series devices.
Platform
Text in this font denotes a specific platform and indicates that the text
following it applies only to that platform.
Related Documentation
Reconfigurable I/O Documentation
This manual is one piece of the documentation set for your reconfigurable
I/O system and application. Depending on the hardware and software
you use for your application, you could have any of several types of
documentation. The documentation includes the following documents:
•
Getting Started with R Series Intelligent DAQ—This document
explains how to install and configure NI 781xR/783xR/784xR/785xR,
and contains a tutorial that demonstrates how to begin taking a
measurement using LabVIEW FPGA. This document is available at
Start»All Programs»National Instruments»NI-RIO. This
document is also available at ni.com/manuals.
•
NI R Series Intelligent DAQ Specifications—Lists the specifications of
the NI 781xR/783xR/784xR/785xR R Series devices. This document is
available at Start»All Programs»National Instruments»NI-RIO.
This document is also available at ni.com/manuals.
•
LabVIEW FPGA documentation
R Series Intelligent DAQ User Manual
–
Getting Started with LabVIEW FPGA 8.x—This KnowledgeBase,
available at ni.com/kb, provides links to the top resources that
can be used to assist in getting started with programming in
LabVIEW FPGA.
–
FPGA Module book in the LabVIEW Help—Select Help»Search
the LabVIEW Help in LabVIEW to view the LabVIEW Help.
Browse the FPGA Module book in the Contents tab for
viii
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About This Manual
information about using the FPGA Module to create VIs that run
on the NI 78xxR device.
–
•
© National Instruments Corporation
LabVIEW FPGA Module Release and Upgrade Notes—Contains
information about installing the LabVIEW FPGA Module,
describes new features, and provides upgrade information.
To access this document, refer to ni.com/manuals. In
LabVIEW 8.0 or later, you can also view the LabVIEW Manuals
directory that contains this document by selecting Start»All
Programs»National Instruments»LabVIEW»LabVIEW
Manuals.
LabVIEW Real-Time documentation
–
Getting Started with the LabVIEW Real-Time Module—Provides
exercises to teach you how to develop a real-time project and VIs,
from setting up RT targets to building, debugging, and deploying
real-time applications. This document provides references to the
LabVIEW Help and other Real-Time Module documents for more
information as you create the real-time application. To access this
document, refer to ni.com/manuals. In LabVIEW 8.0 or later,
you can also view the LabVIEW Manuals directory that contains
this document by selecting Start»All Programs»National
Instruments»LabVIEW»LabVIEW Manuals.
–
Real-Time Module book in the LabVIEW Help—Select Help»
Search the LabVIEW Help in LabVIEW to view the LabVIEW
Help. Browse the Real-Time Module book in the Contents tab
for information about how to build deterministic applications
using the LabVIEW Real-Time Module.
–
LabVIEW Real-Time Module Release and Upgrade
Notes—Includes information about system requirements,
installation, configuration, new features and changes, and
compatibility issues for the LabVIEW Real-Time Module.
To access this document, refer to ni.com/manuals. In
LabVIEW 8.0 or later, you can also view the LabVIEW Manuals
directory that contains this document by selecting Start»All
Programs»National Instruments»LabVIEW»LabVIEW
Manuals.
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R Series Intelligent DAQ User Manual
About This Manual
Additional Resources
The following documents contain information you might find helpful:
•
NI Developer Zone tutorial, Field Wiring and Noise Considerations
for Analog Signals, at ni.com/zone
•
PICMG CompactPCI 2.0 R3.0
•
PXI Hardware Specification Revision 2.1
•
PXI Software Specification Revision 2.1
•
National Instruments Example Finder—LabVIEW contains an
extensive library of VIs and example programs for use with R Series
devices. To access the NI Example Finder, open LabVIEW and select
Help»Find Examples, then select Hardware Input and Output»
R Series.
•
LabVIEW FPGA IPNet—Offers resources for browsing,
understanding, and downloading LabVIEW FPGA functions or IP
(Intellectual Property). Use this resource to acquire IP that you need
for your application, download examples to help learn programming
techniques, and explore the depth of IP offered by the LabVIEW
FPGA platform. To access the LabVIEW FPGA IPNet, visit
ni.com/ipnet.
R Series Intelligent DAQ User Manual
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1
Introduction
This chapter describes the NI 781xR/783xR/784xR/785xR, the concept of
the Reconfigurable I/O (RIO) device, optional software and equipment for
using the NI 78xxR, and safety information about the NI 78xxR.
About the Reconfigurable I/O Device
Table 1-1 lists an overview of the NI 78xxR R Series Intelligent DAQ RIO
devices.
Table 1-1. NI 78xxR R Series Intelligent DAQ RIO Device Overview
Device
I/O Channels
FPGA
AI Sample Rate
NI PCI/PXI-7811R
160 DIO
Virtex-II XC2V1000
—
NI PCI/PXI-7813R
160 DIO
Virtex-II XC2V3000
—
NI PCI/PXI-7830R
4 AI, 4 AO, 56 DIO
Virtex-II XC2V1000
200 kS/s
NI PCI/PXI-7831R
8 AI, 8 AO, 96 DIO
Virtex-II XC2V1000
200 kS/s
NI PCI/PXI-7833R
8 AI, 8 AO, 96 DIO
Virtex-II XC2V3000
200 kS/s
NI PXI-7841R
8 AI, 8 AO, 96 DIO
Virtex-5 LX30
200 kS/s
NI PXI-7842R
8 AI, 8 AO, 96 DIO
Virtex-5 LX50
200 kS/s
NI PXI-7851R
8 AI, 8 AO, 96 DIO
Virtex-5 LX30
750 kS/s
NI PXI-7852R
8 AI, 8 AO, 96 DIO
Virtex-5 LX50
750 kS/s
NI PXI-7853R
8 AI, 8 AO, 96 DIO
Virtex-5 LX85
750 kS/s
NI PXI-7854R
8 AI, 8 AO, 96 DIO
Virtex-5 LX110
750 kS/s
A user-reconfigurable FPGA (Field-Programmable Gate Array) controls
the digital I/O lines on the NI 781xR, and the digital and analog I/O lines
on the NI 783xR/784xR/785xR. The FPGA on the R Series device allows
you to define the functionality and timing of the device. You can change the
functionality of the FPGA on the R Series device in LabVIEW using the
LabVIEW FPGA Module to create and download a custom virtual
© National Instruments Corporation
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R Series Intelligent DAQ User Manual
Chapter 1
Introduction
instrument (VI) to the FPGA. Using the FPGA Module, you can
graphically design the timing and functionality of the R Series device.
If you only have LabVIEW but not the FPGA Module, you cannot create
new FPGA VIs, but you can create VIs that run on Windows or a LabVIEW
Real-Time (RT) target to control existing FPGA VIs.
Some applications require tasks such as real-time, floating-point
processing or datalogging while performing I/O and logic on the R Series
device. You can use the LabVIEW Real-Time Module to perform these
additional applications while communicating with and controlling the
R Series device.
The R Series device contains flash memory to store a startup VI for
automatic loading of the FPGA when the system is powered on.
The NI 78xxR uses the Real-Time System Integration (RTSI) bus to easily
synchronize several measurement functions to a common trigger or timing
event. R Series PCI devices access the RTSI bus through a RTSI cable
connected between devices. R Series PXI devices access the RTSI bus
through the PXI trigger lines implemented on the PXI backplane.
Refer to the NI R Series Intelligent DAQ Specifications, available at
ni.com/manuals, for detailed device specifications.
Using PXI with CompactPCI
Using PXI-compatible products with standard CompactPCI products is an
important feature provided by PXI Hardware Specification Revision 2.1
and PXI Software Specification Revision 2.1. If you use a PXI-compatible
plug-in card in a standard CompactPCI chassis, you cannot use
PXI-specific functions, but you still can use the basic plug-in card
functions. For example, the RTSI bus on the R Series device is available
in a PXI chassis but not in a CompactPCI chassis.
The CompactPCI specification permits vendors to develop sub-buses that
coexist with the basic PCI interface on the CompactPCI bus. Compatible
operation is not guaranteed between CompactPCI devices with different
sub-buses nor between CompactPCI devices with sub-buses and PXI.
The standard implementation for CompactPCI does not include these
sub-buses. The R Series device works in any standard CompactPCI chassis
adhering to the PICMG CompactPCI 2.0 R3.0 core specification.
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Chapter 1
Introduction
PXI-specific features are implemented on the J2 connector of the
CompactPCI bus. Table 1-2 lists the J2 pins used by the NI PXI-78xxR.
The NI 78xxR is compatible with any CompactPCI chassis with a sub-bus
that does not drive these lines. Even if the sub-bus is capable of driving
these lines, the R Series device is still compatible as long as those pins on
the sub-bus are disabled by default and are never enabled.
Caution
Damage can result if the J2 lines are driven by the sub-bus.
Table 1-2. Pins Used by the NI PXI-78xxR
NI PXI-78xxR Signal
PXI Pin Name
PXI J2 Pin Number
PXI Trigger<0..7>
PXI Trigger<0..7>
A16, A17, A18, B16, B18, C18, E16, E18
PXI Clock 10 MHz
PXI Clock 10 MHz
E17
PXI Star Trigger
PXI Star Trigger
D17
LBLSTAR<0..12>*
LBL<0..12>
A1, A19, C1, C19, C20, D1, D2, D15, D19,
E1, E2, E19, E20
LBR<0..12>*
LBR<0..12>
A2, A3, A20, A21, B2, B20, C3, C21,
D3, D21, E3, E15, E21
*
NI PXI-781xR/783xR only
Overview of Reconfigurable I/O
This section explains reconfigurable I/O and describes how to use the
LabVIEW FPGA Module to build high-level functions in hardware.
Refer to Chapter 2, Hardware Overview of the NI 78xxR, for descriptions
of the I/O resources on the NI 78xxR.
Reconfigurable I/O Concept
R Series Intelligent DAQ devices are based on a reconfigurable FPGA core
surrounded by fixed I/O resources for analog and digital input and output.
You can configure the behavior of the reconfigurable FPGA to match the
requirements of the measurement and control system. You can implement
this user-defined behavior as an FPGA VI to create an application-specific
I/O device.
© National Instruments Corporation
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R Series Intelligent DAQ User Manual
Chapter 1
Introduction
Flexible Functionality
Flexible functionality allows the NI 78xxR to match individual application
requirements and to mimic the functionality of fixed I/O devices. For
example, you can configure an R Series device in one application for
three 32-bit quadrature encoders and then reconfigure the R Series device
in another application for eight 16-bit event counters.
You also can use the R Series device with the LabVIEW Real-Time
Module in timing and triggering applications, such as control and
hardware-in-the-loop (HIL) simulations. For example, you can configure
the R Series device for a single timed loop in one application and then
reconfigure the device in another application for four independent timed
loops with separate I/O resources.
User-Defined I/O Resources
You can create your own custom measurements using the fixed I/O
resources. For example, one application might require an event counter that
increments when a rising edge appears on any of three digital input lines.
With a multifunction R Series device, another application might require a
digital line to be asserted after an analog input exceeds a programmable
threshold. You can implement these behaviors in the hardware for fast,
deterministic performance.
Device-Embedded Logic and Processing
You can implement LabVIEW logic and processing in the FPGA of the
R Series device. Typical logic functions include Boolean operations,
comparisons, and basic mathematical operations. You can implement
multiple functions efficiently in the same design, operating sequentially or
in parallel. You also can implement more complex algorithms such as
control loops. You are limited only by the size of the FPGA.
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Chapter 1
Introduction
Reconfigurable I/O Architecture
Figure 1-1 shows an FPGA connected to fixed I/O resources and a bus
interface. The fixed I/O resources include A/D converters (ADCs),
D/A converters (DACs), and digital I/O lines.
Fixed I/O Resource
Fixed I/O Resource
FPGA
Fixed I/O Resource
Fixed I/O Resource
Bus Interface
Figure 1-1. High-Level FPGA Functional Overview
Software accesses the R Series device through the bus interface, and the
FPGA connects the bus interface and the fixed I/O to make possible timing,
triggering, processing, and custom I/O measurements using the LabVIEW
FPGA Module.
The FPGA logic provides timing, triggering, processing, and custom I/O
measurements. Each fixed I/O resource used by the application uses a small
portion of the FPGA logic that controls the fixed I/O resource. The bus
interface also uses a small portion of the FPGA logic to provide software
access to the device.
The remaining FPGA logic is available for higher-level functions such as
timing, triggering, and counting. The functions use varied amounts of logic.
You can place useful applications in the FPGA. How much FPGA space
your application requires depends on your need for I/O recovery, I/O, and
logic algorithms.
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The FPGA does not retain the VI when the R Series device is powered off,
so you must reload the VI each time you power on the device. You can load
the VI from onboard flash memory or from software over the bus interface.
One advantage to using flash memory is that the VI can start executing
almost immediately after power up, instead of waiting for the computer to
completely boot and load the FPGA VI. Refer to the LabVIEW Help for
more information about how to store your VI in flash memory.
Reconfigurable I/O Applications
You can use the LabVIEW FPGA Module to create or acquire new VIs
for your application. The FPGA Module allows you to define custom
functionality for the R Series device using a subset of LabVIEW
functionality. Refer to the R Series examples, available in LabVIEW by
selecting Help»Find Examples, and then selecting Hardware Input and
Output»R Series, for examples of FPGA VIs.
Software Development
You can use LabVIEW with the LabVIEW FPGA Module to program the
NI 78xxR. To develop real-time applications that control the NI 78xxR, use
LabVIEW with the LabVIEW Real-Time Module.
LabVIEW FPGA Module
The LabVIEW FPGA Module enables you to use LabVIEW to create VIs
that run on the FPGA of the R Series target device. Use the FPGA Module
VIs and functions to control the I/O, timing, and logic of the R Series
device and to generate interrupts for synchronization. Select Help»Search
the LabVIEW Help to view the LabVIEW Help. In the LabVIEW Help,
use the Contents tab to browse to the FPGA Interface book for more
information about the FPGA Interface functions.
You can use Interactive Front Panel Communication to communicate
directly with the FPGA VI running on the FPGA target. You can use
Programmatic FPGA Interface Communication to programmatically
control and communicate with FPGA VIs from host VIs.
Use the FPGA Interface functions when you target LabVIEW for Windows
or an RT target to create host VIs that wait for interrupts and control the
FPGA by reading and writing the FPGA VI running on the R Series device.
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If you use the R Series device without the FPGA Module, you can use the RIO
Device Setup utility, available by selecting Start»All Programs»National Instruments»
NI-RIO»RIO Device Setup to download precomplied FPGA VIs to the flash memory of
the R Series device. This utility installs with NI-RIO. You also can use the utility to
configure the analog input mode, to synchronize the clock on the R Series device to the
PXI clock (for NI PXI-78xxR only), and to configure when the VI loads from flash
memory. For more information about using the RIO Device Setup utility, refer to the
RIO Device Setup Help, found at Start»All Programs»National Instruments»NI-RIO»
RIO Device Setup Help.
Note
LabVIEW Real-Time Module
The LabVIEW Real-Time Module extends the LabVIEW development
environment to deliver deterministic, real-time performance.
You can write host VIs that run in Windows or on RT targets to
communicate with FPGA VIs that run on the NI 78xxR. You can develop
real-time VIs with LabVIEW and the LabVIEW Real-Time Module, and
then download the VIs to run on a hardware target with a real-time
operating system. The LabVIEW Real-Time Module allows you to use the
NI 78xxR in RT Series PXI systems being controlled in real time by a VI.
The NI 781xR is designed as a single-point DIO complement to the
LabVIEW Real-Time Module. The NI 783xR/784xR/785xR is designed as
a single-point AI, AO, and DIO complement to the LabVIEW Real-Time
Module. Refer to the LabVIEW Help, available by selecting Help»Search
the LabVIEW Help, for more information about the LabVIEW
Real-Time Module.
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Cables and Accessories
National Instruments offers a variety of products you can use with R Series
devices, including cables, connector blocks, and other accessories,
as shown in Table 1-3.
Table 1-3. R Series Connectivity Options
Cable
Connector
Accessory
0
NI SCB-68
High-performance shielded cable wired
specifically for signal connection from
the RMIO connector† to the NI SCB-68
terminal block to provide higher signal
integrity and noise immunity.
1, 2
NI SCB-68
High-performance shielded cable wired
specifically for signal connection from the
RDIO connector† to the NI SCB-68
terminal block to provide higher signal
integrity and noise immunity.
0, 1, 2
NI SCB-68
Basic shielded cable for signal connection
from the RMIO or RDIO connector to the
NI SCB-68 terminal block for noise
reduction.
—
—
For use with the NI PXI-78xxR running
the LabVIEW Real-Time Module, if the
real-time PXI system is not configured on
a network. To connect the PXI system to
a network port, use a standard CAT 5
10/100Base-T Ethernet cable.
SHC68-68-RMIO*
(NI Recommended)
SHC68-68-RDIO
(NI Recommended)
SH68-C68-S
CAT 5 Ethernet
crossover cable*
*
Description
NI 783xR/784xR/785xR devices only.
†
For a diagram of the twisted pairs in the SHC68-68-RMIO and SHC68-68-RDIO cables and the signals to which they
correspond, go to ni.com/info and enter the info code rdrmio.
Refer to Appendix A, Connecting I/O Signals, for more information
about using these cables and accessories to connect I/O signals to the
NI 78xxR. Refer to ni.com/products or contact the sales office nearest
to you for the most current cabling options.
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Custom Cabling
NI offers a variety of cables for connecting signals to the NI 78xxR. If you
need to develop a custom cable, a nonterminated shielded cable is available
from NI. The SHC68-NT-S connects to the NI 78xxR VHDCI connectors
on one end of the cable. The other end of the cable is not terminated. This
cable ships with a wire list identifying the wires that correspond to each
NI 78xxR pin. You can use this cable to quickly connect the NI 78xxR
signals that you need to the connector of your choice. Refer to Appendix A,
Connecting I/O Signals, for the NI 78xxR connector pinouts.
Safety Information
The following section contains important safety information that you must
follow when installing and using the NI 78xxR.
Do not operate the device in a manner not specified in this document.
Misuse of the module can result in a hazard. You can compromise the safety
protection built into the device if the module is damaged in any way. If the
device is damaged, return it to NI for repair.
Do not substitute parts or modify the device except as described in this
document. Use the device 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 device.
Do not operate the device in an explosive atmosphere or where there may
be flammable gases or fumes. If you must operate the device in such an
environment, it must be in a suitably rated enclosure.
If you need to clean the device, use a soft, nonmetallic brush. Make sure
that the device is completely dry and free from contaminants before
returning it to service.
Operate the device only at or below Pollution Degree 2. 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.
© National Instruments Corporation
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•
Pollution Degree 3 means that conductive pollution occurs, or dry,
nonconductive pollution occurs that becomes conductive due to
condensation.
You must insulate signal connections for the maximum voltage for which
the device is rated. Do not exceed the maximum ratings for the device. Do
not install wiring while the device is live with electrical signals. Do not
remove or add connector blocks when power is connected to the system.
Avoid contact between your body and the connector block signal when hot
swapping modules. Remove power from signal lines before connecting
them to or disconnecting them from the device.
Operate the device at or below the measurement category1 marked on the
hardware label. Measurement circuits are subjected to working voltages2
and transient stresses (overvoltage) from the circuit to which they are
connected during measurement or test. Installation categories establish
standard impulse withstand voltage levels that commonly occur in
electrical distribution systems. The following is a description of installation
categories:
1
2
3
•
Measurement Category I is for measurements performed on circuits
not directly connected to the electrical distribution system referred to
as MAINS3 voltage. This category is for measurements of voltages
from specially protected secondary circuits. Such voltage
measurements include signal levels, special equipment, limited-energy
parts of equipment, circuits powered by regulated low-voltage sources,
and electronics.
•
Measurement Category II is for measurements performed on circuits
directly connected to the electrical distribution system. This category
refers to local-level electrical distribution, such as that provided by a
standard wall outlet (for example, 115 AC voltage for U.S. or 230 AC
voltage for Europe). Examples of Measurement Category II are
measurements performed on household appliances, portable tools,
and similar modules.
Measurement categories, also referred to as installation categories, are defined in electrical safety standard IEC 61010-1.
Working voltage is the highest rms value of an AC or DC voltage that can occur across any particular insulation.
MAINS is defined as a hazardous live electrical supply system that powers equipment. Suitably rated measuring circuits may
be connected to the MAINS for measuring purposes.
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•
Measurement Category III is for measurements performed in the
building installation at the distribution level. This category refers to
measurements on hard-wired equipment such as equipment in fixed
installations, distribution boards, and circuit breakers. Other examples
are wiring, including cables, bus bars, junction boxes, switches, socket
outlets in the fixed installation, and stationary motors with permanent
connections to fixed installations.
•
Measurement Category IV is for measurements performed at the
primary electrical supply installation (<1,000 V). Examples include
electricity meters and measurements on primary overcurrent
protection devices and on ripple control units.
© National Instruments Corporation
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R Series Intelligent DAQ User Manual
2
Hardware Overview
of the NI 78xxR
This chapter presents an overview of the hardware functions and
I/O connectors on the NI 78xxR.
Figure 2-1 shows a block diagram for the NI 781xR. Figure 2-2 shows a
block diagram for the NI 7830R. Figure 2-3 shows a block diagram for the
NI 7831R/7833R/784xR/785xR.
Digital I/O (40)
User-Configurable
FPGA on
RIO Devices
Data/Address/Control
Bus
Interface
Control
Address/Data
PXI Local Bus (NI PXI-781x R Only)
RTSI/PXI Triggers
Connector 2 (DIO)
Configuration
Connector 0 (DIO)
Connector 1 (DIO)
Digital I/O (40)
Connector 3 (DIO)
Digital I/O (40)
PCI/PXI/CompactPCI Bus
Flash Memory
Configuration Control
RTSI Bus
Digital I/O (40)
Figure 2-1. NI 781xR Block Diagram
© National Instruments Corporation
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R Series Intelligent DAQ User Manual
Hardware Overview of the NI 78xxR
+
–
x4 Channels
Input Mode Mux
AISENSE
AIGND
Voltage
Reference
Calibration
Mux
16-Bit
DAC
Configuration
Control
16-Bit
ADC
Instrumentation
Ampliflier
AI–
Connector 0 (MIO)
Calibration
DACs
Input Mux
UserConfigurable
FPGA on RIO
Devices
Temperature
Sensor
2 Calibration
DACs
Flash
Memory
Data/Address/
Control
Bus
Interface
Control
Address/Data
x4 Channels
PCI/PXI/CompactPCI Bus
AI+
Configuration
Chapter 2
Digital I/O (40)
PXI Local Bus (NI PXI-7830R only)
RTSI Bus
RTSI/PXI Triggers
Connector 1 (DIO)
Digital I/O (16)
Figure 2-2. NI 7830R Block Diagram
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Calibration
DACs
+
Instrumentation
Amplifier
AI–
16-Bit
ADC
–
Connector 0 (MIO)
Configuration
Control
x8 Channels
Flash
Memory
Configuration
Input Mux
AI+
Hardware Overview of the NI 78xxR
Input Mode Mux
AISENSE
AIGND
Voltage
Reference
Calibration
Mux
16-Bit
DAC
UserConfigurable
FPGA on RIO
Devices
Temperature
Sensor
2 Calibration
DACs
Data/Address/
Control
Bus
Interface
Control
Address/Data
x8 Channels
PCI/PXI/CompactPCI Bus
Chapter 2
Digital I/O (40)
PXI Local Bus (NI PXI-783xR only)
RTSI Bus
Digital I/O (40)
RTSI/PXI Triggers
Connector 2 (DIO)
Connector 1 (DIO)
Digital I/O (16)
Figure 2-3. NI 7831R/7833R/784xR/785xR Block Diagram
NI 7811R Overview
The NI 7811R has 160 bidirectional DIO lines and a Virtex-II XC2V1000
FPGA.
NI 7813R Overview
The NI 7813R has 160 bidirectional DIO lines and a Virtex-II XC2V3000
FPGA.
NI 7830R Overview
The NI 7830R has four independent, 16-bit AI channels; four independent,
16-bit AO channels; 56 bidirectional DIO lines that you can configure
individually for input or output; and a Virtex-II XC2V1000 FPGA.
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Hardware Overview of the NI 78xxR
NI 7831R/7833R Overview
The NI 7831R/7833R each have eight independent, 16-bit AI channels;
eight independent, 16-bit AO channels; 96 bidirectional DIO lines that you
can configure individually for input or output; and a Virtex-II XC2V3000
FPGA.
NI 784xR Overview
The NI 784xR each have eight independent, 16-bit AI channels;
eight independent, 16-bit AO channels; and 96 bidirectional DIO lines that
you can configure individually for input or output. The NI PXI-7841R has
a Virtex-5 LX30 FPGA, and the NI PXI-7842R has a Virtex-5 LX50
FPGA.
NI 785xR Overview
The NI 785xR each have eight independent, 16-bit AI channels;
eight independent, 16-bit AO channels; and 96 bidirectional DIO lines that
you can configure individually for input or output. The NI PXI-7851R has
a Virtex-5 LX30 FPGA, the NI PXI-7852R has a Virtex-5 LX50 FPGA,
the NI PXI-7853R has a Virtex-5 LX85 FPGA, and the NI PXI-7854R has
a Virtex-5 LX110 FPGA.
Analog Input (Multifunction R Series Only)
You can sample NI 783xR/784xR/785xR AI channels simultaneously or at
different rates. The input mode is software configurable, and the input
range is fixed at ±10 V. The converters return data in two’s complement
format. Table 2-1 shows the ideal output code returned for a given AI
voltage.
Table 2-1. Ideal Output Code and AI Voltage Mapping
AI Voltage
Output Code (Hex)
(Two’s Complement)
Full-scale range –1 LSB
9.999695
7FFF
Full-scale range –2 LSB
9.999390
7FFE
Midscale
0.000000
0000
Input Description
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Table 2-1. Ideal Output Code and AI Voltage Mapping (Continued)
Input Description
AI Voltage
Output Code (Hex)
(Two’s Complement)
Negative full-scale range +1 LSB
–9.999695
8001
Negative full-scale range
–10.000000
8000
Output Code
---------------------------------- × 10.0 V
32,768
—
Any input voltage
Input Modes
The NI 783xR/784xR/785xR input mode is software configurable. The
input channels support three input modes—differential (DIFF), referenced
single ended (RSE), and nonreferenced single ended (NRSE). The selected
input mode applies to all the input channels. Table 2-2 describes the three
input modes.
Table 2-2. Available Input Modes for the NI 783xR/784xR/785xR
Input Mode
Description
DIFF
When the NI 783xR/784xR/785xR is configured in DIFF input mode, each
channel uses two AI lines. The positive input pin connects to the positive terminal
of the onboard instrumentation amplifier. The negative input pin connects to the
negative input of the instrumentation amplifier.
RSE
When the NI 783xR/784xR/785xR is configured in RSE input mode, each
channel uses only its positive AI pin. This pin connects to the positive terminal
of the onboard instrumentation amplifier. The negative input of the
instrumentation amplifier connects internally to the AI ground (AIGND).
NRSE
When the NI 783xR/784xR/785xR is configured in NRSE input mode, each
channel uses only its positive AI pin. This pin connects to the positive terminal
of the onboard instrumentation amplifier. The negative input of the
instrumentation amplifier on each AI channel connects internally to the
AISENSE input pin.
Input Range
The NI 783xR/784xR/785xR AI range is fixed at ±10 V.
© National Instruments Corporation
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Hardware Overview of the NI 78xxR
Connecting Analog Input Signals
The AI signals for the NI 783xR/784xR/785xR are AI<0..n>+, AI<0..n>–,
AIGND, and AISENSE. For the NI 7830R, n=4. For the
NI 7831R/7833R/784xR/785xR, n=8. The AI<0..n>+ and AI<0..n>–
signals are connected to the eight AI channels of the
NI 783xR/784xR/785xR. For all input modes, the AI<0..n>+ signals are
connected to the positive input of the instrumentation amplifier on each
channel. The signal connected to the negative input of the instrumentation
amplifier depends on how you configure the input mode of the device.
In differential input mode, signals connected to AI<0..n>– are routed to the
negative input of the instrumentation amplifier for each channel. In RSE
input mode, the negative input of the instrumentation amplifier for each
channel is internally connected to AIGND. In NRSE input mode, the
AISENSE signal is connected internally to the negative input of the
instrumentation amplifier for each channel. In DIFF and RSE input modes,
AISENSE is not used.
Caution Exceeding the differential and common-mode input ranges distorts the
input signals. Exceeding the maximum input voltage rating can damage the
NI 783xR/784xR/785xR and the computer. NI is not liable for any damage resulting from
such signal connections. The maximum input voltage ratings are listed in Table A-2,
NI 78xxR I/O Signal Summary.
AIGND is a common AI signal that is routed directly to the ground tie point
on the NI 783xR/784xR/785xR. You can use this signal for a general analog
ground tie point to the NI 783xR/784xR/785xR if necessary.
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Connection of AI signals to the NI 783xR/784xR/785xR depends on the
input mode of the AI channels you are using and the type of input signal
source. With different input modes, you can use the instrumentation
amplifier in different ways. Figure 2-4 shows a diagram of the
NI 783xR/784xR/785xR instrumentation amplifier.
Vin+
+
Instrumentation
Amplifier
+
Vm
–
–
Vin–
Measured
Voltage
Vm = [Vin+ – Vin–]
Figure 2-4. NI 783xR/784xR/785xR Instrumentation Amplifier
The instrumentation amplifier applies common-mode voltage rejection
and presents high input impedance to the AI signals connected to the
NI 783xR/784xR/785xR. Input multiplexers on the device route signals to
the positive and negative inputs of the instrumentation amplifier. The
instrumentation amplifier converts two input signals to a signal that is the
difference between the two input signals. The amplifier output voltage is
referenced to the device ground. The NI 783xR/784xR/785xR ADC
measures this output voltage when it performs A/D conversions.
You must reference all signals to ground either at the source device or at the
NI 783xR/784xR/785xR. If you have a floating source, reference the signal
to ground by using RSE input mode or the DIFF input mode with bias
resistors. Refer to the Differential Connections for Nonreferenced or
Floating Signal Sources section of this chapter for more information about
these input modes. If you have a grounded source, do not reference the
signal to AIGND. You can avoid this reference by using DIFF or NRSE
input modes.
© National Instruments Corporation
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Hardware Overview of the NI 78xxR
Types of Signal Sources
When configuring the input channels and making signal connections,
you must first determine whether the signal sources are floating or ground
referenced. The following sections describe these two signal types.
Floating Signal Sources
A floating signal source is not connected to the building ground system but
instead has an isolated ground-reference point. Some examples of floating
signal sources are outputs of transformers, thermocouples, battery-powered
devices, optical isolator outputs, and isolation amplifiers. An instrument
or device that has an isolated output is a floating signal source.
You must connect the ground reference of a floating signal to the
NI 783xR/784xR/785xR AIGND through a bias resistor to establish a local
or onboard reference for the signal. Otherwise, the measured input signal
varies as the source floats out of the common-mode input range.
Ground-Referenced Signal Sources
A ground-referenced signal source is connected to the building system
ground, so it is already connected to a common ground point with respect
to the NI 783xR/784xR/785xR, assuming that the computer is plugged into
the same power system. Instruments or devices with nonisolated outputs
that plug into the building power system are ground referenced signal
sources.
The difference in ground potential between two instruments connected to
the same building power system is typically between 1 and 100 mV. This
difference can be much higher if power distribution circuits are improperly
connected. If a grounded signal source is improperly measured, this
difference might appear as a measurement error. The connection
instructions for grounded signal sources are designed to eliminate this
ground potential difference from the measured signal.
Input Modes
The following sections discuss single-ended and differential measurements
and considerations for measuring both floating and ground-referenced
signal sources.
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Figure 2-5 summarizes the recommended input mode for both types of
signal sources.
Signal Source Type
Floating Signal Source
(Not Connected to Building Ground)
Grounded Signal Source
Examples
• Ungrounded Thermocouples
• Signal Conditioning with
Isolated Outputs
• Battery Devices
Examples
• Plug-in Instruments with
Nonisolated Outputs
Input
AI<i>(+)
+ V
1
–
AI<i>(–)
+
–
AI<i>(+)
+ V
1
–
+
AI<i>(–)
–
Differential
(DIFF)
AIGND<i>
AIGND<i>
See text for information on bias resistors.
NOT RECOMMENDED
AI<i>
+ V
1
–
Single-Ended—
Ground
Referenced
(RSE)
+
AIGND<i>
–
AI
+
+ V
1
–
–
+ Vg –
AIGND
Ground-loop losses, Vg, are added to
measured signal.
AI<i>
+ V
1
–
Single-Ended—
Nonreferenced
(NRSE)
+
AISENSE
–
AI<i>
+ V
1
–
+
AISENSE
–
AIGND<i>
AIGND<i>
See text for information on bias resistors.
Figure 2-5. Summary of Analog Input Connections
© National Instruments Corporation
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Hardware Overview of the NI 78xxR
Differential Connection Considerations (DIFF Input Mode)
In DIFF input mode, the NI 783xR/784xR/785xR measures the difference
between the positive and negative inputs. DIFF input mode is ideal for
measuring ground-referenced signals from other devices. When using
DIFF input mode, the input signal connects to the positive input of the
instrumentation amplifier and its reference signal, or return, connects to the
negative input of the instrumentation amplifier.
Use differential input connections for any channel that meets any of the
following conditions:
•
The input signal is low level (less than 1 V).
•
The leads connecting the signal to the NI 783xR/784xR/785xR are
greater than 3 m (10 ft).
•
The input signal requires a separate ground-reference point or return
signal.
•
The signal leads travel through noisy environments.
Differential signal connections reduce noise pickup and increase
common-mode noise rejection. Differential signal connections also
allow input signals to float within the common-mode limits of the
instrumentation amplifier.
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Differential Connections for Ground-Referenced
Signal Sources
Figure 2-6 shows how to connect a ground-referenced signal source to a
channel on the NI 783xR/784xR/785xR configured in DIFF input mode.
AI+
GroundReferenced
Signal
Source
+
+
AI–
Instrumentation
Amplifier
Vs
–
–
+
Vm
–
CommonMode
Noise and
Ground
Potential
Measured
Voltage
+
Vcm
AISENSE
–
AIGND
I/O Connector
DIFF Input Mode Selected
Figure 2-6. Differential Input Connections for Ground-Referenced Signals
With this connection type, the instrumentation amplifier rejects both the
common-mode noise in the signal and the ground potential difference
between the signal source and the NI 783xR/784xR/785xR ground, shown
as Vcm in Figure 2-6. In addition, the instrumentation amplifier can reject
common-mode noise pickup in the leads connecting the signal sources to
the device. The instrumentation amplifier can reject common-mode signals
when V+in and V– in (input signals) are both within their specified input
ranges. Refer to the NI R Series Intelligent DAQ Specifications, available at
ni.com/manuals, for more information about input ranges.
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Differential Connections for Nonreferenced or
Floating Signal Sources
Figure 2-7 shows how to connect a floating signal source to a channel on
the NI 783xR/784xR/785xR configured in DIFF input mode.
Floating
Signal
Source
+
Vs
Bias
Resistors
(see text)
AI+
+
AI–
Instrumentation
Amplifier
–
–
+
Vm
–
Measured
Voltage
Bias
Current
Return
Paths
AISENSE
AIGND
I/O Connector
DIFF Input Mode Selected
Figure 2-7. Differential Input Connections for Nonreferenced Signals
Figure 2-7 shows two bias resistors connected in parallel with the signal
leads of a floating signal source. If you do not use the resistors and the
source is truly floating, the source might not remain within the
common-mode signal range of the instrumentation amplifier, causing
erroneous readings. You must reference the source to AIGND by
connecting the positive side of the signal to the positive input of the
instrumentation amplifier and connecting the negative side of the signal to
AIGND and to the negative input of the instrumentation amplifier without
resistors. This connection works well for DC-coupled sources with low
source impedance, less than 100 Ω.
For larger source impedances, this connection leaves the differential signal
path significantly out of balance. Noise that couples electrostatically onto
the positive line does not couple onto the negative line because it is
connected to ground. Hence, this noise appears as a differential-mode
signal instead of a common-mode signal, and the instrumentation amplifier
does not reject it. In this case, instead of directly connecting the negative
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line to AIGND, connect it to AIGND through a resistor that is about
100 times the equivalent source impedance. The resistor puts the signal
path nearly in balance. About the same amount of noise couples onto both
connections, which yields better rejection of electrostatically coupled
noise. Also, this input mode does not load down the source, other than the
very high-input impedance of the instrumentation amplifier.
You can fully balance the signal path by connecting another resistor of the
same value between the positive input and AIGND, as shown in Figure 2-7.
This fully balanced input mode offers slightly better noise rejection but has
the disadvantage of loading down the source with the series combination
(sum) of the two resistors. If, for example, the source impedance is 2 kΩ
and each of the two resistors is 100 kΩ, the resistors load down the source
with 200 kΩ and produce a –1% gain error.
Both inputs of the instrumentation amplifier require a DC path to ground
for the instrumentation amplifier to work. If the source is AC coupled
(capacitively coupled), the instrumentation amplifier needs a resistor
between the positive input and AIGND. If the source has low-impedance,
choose a resistor that is large enough not to significantly load the source but
small enough not to produce significant input offset voltage as a result of
input bias current, typically 100 kΩ to 1 MΩ. In this case, connect the
negative input directly to AIGND. If the source has high output impedance,
balance the signal path as previously described using the same value
resistor on both the positive and negative inputs. Loading down the source
causes some gain error.
Single-Ended Connection Considerations
When an NI 783xR/784xR/785xR AI signal is referenced to a ground that
can be shared with other input signals, it forms a single-ended connection.
The input signal connects to the positive input of the instrumentation
amplifier and the ground connects to the negative input of the
instrumentation amplifier.
You can use single-ended input connections for any input signal that meets
the following conditions:
•
The input signal is high-level (>1 V).
•
The leads connecting the signal to the NI 783xR/784xR/785xR are less
than 3 m (10 ft).
•
The input signal can share a common reference point with other
signals.
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Use DIFF input connections for greater signal integrity for any input signal
that does not meet the preceding conditions.
You can configure the NI 783xR/784xR/785xR channels in software for
RSE or NRSE input modes. Use the RSE input mode for floating signal
sources. In this case, the NI 783xR/784xR/785xR provides the reference
ground point for the external signal. Use the NRSE input mode for
ground-referenced signal sources. In this case, the external signal supplies
its own reference ground point and the NI 783xR/784xR/785xR should not
supply one.
In single-ended input modes, electrostatic and magnetic noise couples into
the signal connections more than in differential input modes. The coupling
is the result of differences in the signal path. Magnetic coupling
is proportional to the area between the two signal conductors. Electrical
coupling is a function of how much the electric field differs between the
two conductors.
Single-Ended Connections for Floating Signal
Sources (RSE Input Mode)
Figure 2-8 shows how to connect a floating signal source to a channel on
the NI 783xR/784xR/785xR configured for RSE input mode.
AI+
+
AI–
Floating
Signal
Source
Instrumentation
Amplifier
–
+
+
Vm
–
Vs
Measured
Voltage
–
AISENSE
AIGND
I/O Connector
RSE Input Mode Selected
Figure 2-8. Single-Ended Input Connections for Nonreferenced or Floating Signals
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Single-Ended Connections for Grounded Signal
Sources (NRSE Input Mode)
To measure a grounded signal source with a single-ended input mode, you
must configure the NI 783xR/784xR/785xR in the NRSE input mode. Then
connect the signal to the positive input of the NI 783xR/784xR/785xR
instrumentation amplifier and connect the signal local ground reference to
the negative input of the instrumentation amplifier. The ground point of the
signal should be connected to AISENSE. Any potential difference between
the NI 783xR/784xR/785xR ground and the signal ground appears as a
common-mode signal at both the positive and negative inputs of the
instrumentation amplifier. The instrumentation amplifier rejects this
difference. If the input circuitry of a NI 783xR/784xR/785xR is referenced
to ground in RSE input mode, this difference in ground potentials appears
as an error in the measured voltage.
Figure 2-9 shows how to connect a grounded signal source to a channel on
the NI 783xR/784xR/785xR configured for NRSE input mode.
GroundReferenced
Signal
Source
+
AI+
+
AI–
Instrumentation
Amplifier
Vs
–
–
+
Vm
–
CommonMode
Noise and
Ground
Potential
Measured
Voltage
+
Vcm
–
AISENSE
AIGND
I/O Connector
NRSE Input Mode Selected
Figure 2-9. Single-Ended Input Connections for Ground-Referenced Signals
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Common-Mode Signal Rejection Considerations
Figure 2-6 and Figure 2-9 show connections for signal sources that
are already referenced to some ground point with respect to the
NI 783xR/784xR/785xR. In these cases, the instrumentation amplifier can
reject any voltage caused by ground potential differences between the
signal source and the device. With differential input connections, the
instrumentation amplifier can reject common-mode noise pickup in the
leads connecting the signal sources to the device. The instrumentation
amplifier can reject common-mode signals when V+in and V– in
(input signals) are both within their specified input ranges. Refer to
the NI R Series Intelligent DAQ Specifications, available at
ni.com/manuals, for more information about input ranges.
Analog Output
The bipolar output range of the NI 783xR/784xR/785xR AO channels is
fixed at ±10 V. Some applications require that the AO channels power on
to known voltage levels. To set the power-on levels, you can configure the
NI 783xR/784xR/785xR to load and run a VI when the system powers on.
The VI can set the AO channels to the desired voltage levels. The VI
interprets data written to the DAC in two’s complement format. Table 2-3
shows the ideal AO voltage generated for a given input code.
Table 2-3. Ideal Output Voltage and Input Code Mapping
AO Voltage
Input Code (Hex)
(Two’s Complement)
Full-scale range –1 LSB
9.999695
7FFF
Full-scale range –2 LSB
9.999390
7FFE
Midscale
0.000000
0000
Negative full-scale range, +1 LSB
–9.999695
8001
Negative full-scale range
–10.000000
8000
—
AO Voltage
------------------------------- × 32,768
10.0 V
Output Description
Any output voltage
If your VI does not set the output value for an AO channel, then the AO channel
voltage output will be undefined.
Note
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Connecting Analog Output Signals
The AO signals are AO <0..n> and AOGND.
AO <0..n> are the AO channels. AOGND is the ground reference signal for
the AO channels.
Figure 2-10 shows how to make AO connections to the
NI 783xR/784xR/785xR.
AO0
+
Channel 0
Load
VOUT 0
–
AOGND0
NI 783xR/784xR/785xR
Figure 2-10. Analog Output Connections
Digital I/O
You can configure the NI 78xxR DIO lines individually for either input or
output. When the system powers on, the DIO lines are at high impedance.
To set another power-on state, you can configure the NI 78xxR to load a VI
when the system powers on. The VI can then set the DIO lines to any
power-on state.
Connecting Digital I/O Signals
The DIO signals on the NI 78xxR RDIO connectors are DGND and
DIO<0..39>. The DIO signals on the NI 783xR/784xR/785xR RMIO
connector are DGND and DIO<0..15>. The DIO<0..n> signals make up the
DIO port and DGND is the ground reference signal for the DIO port. The
NI 781xR has four RDIO connectors for a total of 160 DIO lines. The
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NI 7830R has one RMIO and one RDIO connector for a total of 56 DIO
lines. The NI 7831R/7833R/784xR/785xR has one RMIO and two RDIO
connectors for a total of 96 DIO lines.
Refer to Figure A-1, NI 781xR Connector Pin Assignments and Locations,
for the connector locations and the I/O connector pin assignments on the
NI 781xR. Refer to Figure A-2, NI 783xR/784xR/785xR Connector Pin
Assignments and Locations, for the connector locations and the I/O
connector pin assignments on the NI 783xR/784xR/785xR.
The DIO lines on the NI 78xxR are TTL-compatible. When configured as
inputs, they can receive signals from 5 V TTL, 3.3 V LVTTL, 5 V CMOS,
and 3.3 V LVCMOS devices. When configured as outputs, they can send
signals to 5 V TTL, 3.3 V LVTTL, and 3.3 V LVCMOS devices. Because
the digital outputs provide a nominal output swing of 0 to 3.3 V
(3.3 V TTL), the DIO lines cannot drive 5 V CMOS logic levels.
To interface to 5 V CMOS devices, you must provide an external pull-up
resistor to 5 V. This resistor pulls up the 3.3 V digital output from the
NI 78xxR to 5 V CMOS logic levels. Refer to the NI R Series Intelligent
DAQ Specifications, available at ni.com/manuals, for detailed DIO
specifications.
Exceeding the maximum input voltage ratings, listed in Table A-2, NI 78xxR I/O
Signal Summary, can damage the NI 78xxR and the computer. NI is not liable for any
damage resulting from such signal connections.
Caution
Do not short the DIO lines of the NI 78xxR directly to power or to ground. Doing
so can damage the NI 78xxR by causing excessive current to flow through the DIO lines.
Caution
You can connect multiple NI 78xxR digital output lines in parallel to
provide higher current sourcing or sinking capability. If you connect
multiple digital output lines in parallel, your application must drive all of
these lines simultaneously to the same value. If you connect digital lines
together and drive them to different values, excessive current can flow
through the DIO lines and damage the NI 78xxR. Refer to the NI R Series
Intelligent DAQ Specifications, available at ni.com/manuals, for more
information about DIO specifications. Figure 2-11 shows signal
connections for three typical DIO applications.
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LED
DGND
+5 V
TTL or
LVCMOS*
Compatible
Devices
DIO<4..7>
5 V CMOS †
TTL, LVTTL, CMOS, or LVCMOS Signal
DIO<0..3>
+5 V
Switch
DGND
I/O Connector
NI 783xR/784xR/785xR
*3.3 V CMOS
†Use a pull-up resistor when driving 5 V CMOS devices.
Figure 2-11. Example Digital I/O Connections
Figure 2-11 shows DIO<0..3> configured for digital input and DIO<4..7>
configured for digital output. Digital input applications include receiving
TTL, LVTTL, CMOS, or LVCMOS signals and sensing external device
states, such as the state of the switch shown in Figure 2-11. Digital output
applications include sending TTL or LVCMOS signals and driving external
devices, such as the LED shown in Figure 2-11.
The NI 78xxR SHC68-68-RDIO cable contains individually shielded
bundles that route each digital signal on an individually shielded pair of
wires, and each signal is twisted with its own wire to digital ground.
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The SHC68-68-RDIO was designed specifically for R Series devices and is
the NI-recommended cable for digital applications. If you are using the
SH68-C68-S cable, however, please note the following considerations.
The SH68-C68-S shielded cable contains 34 twisted pairs of conductors. To
maximize the digital I/O available on the NI 78xxR, some of the DIO lines
are twisted with power or ground and some DIO lines are twisted with other
DIO lines. To obtain maximum signal integrity, place edge-sensitive or
high-frequency digital signals on the DIO lines that are paired with power
or ground. Because the DIO lines that are twisted with other DIO lines can
couple noise onto each other, use these lines for static signals or
non-edge-sensitive, low-frequency digital signals. Examples of
high-frequency or edge-sensitive signals include clock, trigger, pulse-width
modulation (PWM), encoder, and counter signals. Examples of static
signals or non-edge-sensitive, low-frequency signals include LEDs,
switches, and relays. Table 2-4 summarizes these guidelines.
Table 2-4. DIO Signal Guidelines for the NI 78xxR
Device
NI 781xR
NI 783xR,
NI 784xR,
NI 785xR
Digital Lines
SH68-C68-S
Shielded Cable
Signal Pairing
Recommended Types
of Digital Signals
DIO<0..27>
DIO line paired
with power
or ground
All types—high-frequency or
low-frequency signals,
edge-sensitive or
non-edge-sensitive signals
DIO<28..39>
DIO line paired
with another
DIO line
Static signals or
non-edge-sensitive,
low-frequency signals
Connector 0, DIO<0..7>;
Connector 1, DIO<0..27>;
Connector 2, DIO<0..27>
DIO line paired
with power
or ground
All types—high-frequency or
low-frequency signals,
edge-sensitive or
non-edge-sensitive signals
Connector 0, DIO<8..15>;
Connector 1, DIO<28..39>;
Connector 2, DIO<28..39>
DIO line paired
with another
DIO line
Static signals or
non-edge-sensitive,
low-frequency signals
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RTSI Trigger Bus
The NI 78xxR can send and receive triggers through the RTSI trigger bus.
The RTSI bus provides eight shared trigger lines that connect to all the
devices on the bus. In PXI, the trigger lines are shared between all the PXI
slots in a bus segment. In PCI, the RTSI bus is implemented through a
ribbon cable connected to the RTSI connector on each device that needs to
access the RTSI bus.
You can use the RTSI trigger lines to synchronize the NI 78xxR to any other
device that supports RTSI triggers. On the NI PCI-781xR/783xR, the RTSI
trigger lines are labeled RTSI/TRIG<0..6> and RTSI/OSC. On the
NI PXI-78xxR, the RTSI trigger lines are labeled PXI/TRIG<0..7>.
In addition, the NI PXI-78xxR can use the PXI star trigger line to send or
receive triggers from a device plugged into Slot 2 of the PXI chassis.
The PXI star trigger line on the NI PXI-78xxR is PXI/STAR.
The NI 78xxR can configure each RTSI trigger line either as an input or an
output signal. Because each trigger line on the RTSI bus is connected in
parallel to all the other RTSI devices on the bus, only one device
should drive a particular RTSI trigger line at a time. For example, if
one NI PXI-78xxR is configured to send out a trigger pulse on PXI/TRIG0,
the remaining devices on that PXI bus segment must have PXI/TRIG0
configured as an input.
Do not drive the same RTSI trigger bus line with the NI 78xxR and another device
simultaneously. Such signal driving can damage both devices. NI is not liable for any
damage resulting from such signal driving.
Caution
For more information on using and configuring triggers, select Help»
Search the LabVIEW Help in LabVIEW to view the LabVIEW Help.
Refer to the PXI Hardware Specification Revision 2.1 and PXI Software
Specification Revision 2.1 at www.pxisa.org for more information about
PXI triggers.
PXI Local Bus (NI PXI-781xR/783xR Only)
The NI PXI-781xR/783xR can communicate with other PXI devices using
the PXI local bus. The PXI local bus is a daisy-chained bus that connects
each PXI peripheral slot with its adjacent peripheral slot on either side. For
example, the right local bus lines from a PXI peripheral slot connect to the
left local bus lines of the adjacent slot on the right. Each local bus is 13 lines
wide. All of these lines connect to the FPGA on the NI PXI-781xR/783xR.
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The PXI local bus right lines on the NI PXI-781xR/783xR are
PXI/LBR<0..12>. The PXI local bus left lines on the NI PXI-781xR/783xR
are PXI/LBLSTAR<0..12>.
The NI PXI-781xR/783xR can configure each PXI local bus line either as
an input or an output signal. Only one device can drive the same physical
local bus line at a time. For example, if the NI PXI-781xR/783xR is
configured to drive a signal on PXI/LBR 0, the device in the slot
immediately to the right must have its PXI/LBLSTAR 0 line configured as
an input.
Do not drive the same PXI local bus line with the NI PXI-781xR/783xR and
another device simultaneously. Such signal driving can damage both devices. NI is not
liable for any damage resulting from such signal driving.
Caution
The NI PXI-781xR/783xR local bus lines are only compatible with 3.3 V
signaling LVTTL and LVCMOS levels.
Caution Do not enable the local bus lines on an adjacent device if the device drives
anything other than 0–3.3V LVTTL signal levels on the NI PXI-781xR/783xR. Enabling
the lines in this way can damage the NI PXI-781xR/783xR. NI is not liable for any damage
resulting from enabling such lines.
The left local bus lines from the left peripheral slot of a PXI backplane
(Slot 2) are routed to the star trigger lines of up to 13 other peripheral slots
in a two-segment PXI system. This configuration provides a dedicated,
delay-matched trigger signal between the first peripheral slot and the
other peripheral slots for precise trigger timing signals. For example—as
shown in Figure 2-12—an NI PXI-781xR/783xR in Slot 2 can send an
independent trigger signal to each device plugged into Slots <3..15> using
the PXI/LBLSTAR<0..12>. Each device receives its trigger signal on its
own dedicated star trigger line.
Do not configure the NI 781xR/783xR and another device to drive the same
physical star trigger line simultaneously. Such signal driving can damage the
NI 781xR/783xR and the other device. NI is not liable for any damage resulting from
such signal driving.
Caution
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LBLStar0
LBLStar1
LBLStar2
LBLStar3
LBR0
LBR1
LBR2
LBR3
Slot 2
LBLStar0
LBLStar1
LBLStar2
LBLStar3
PXI Star
LBR0
LBR1
LBR2
LBR3
Trigger 0
Trigger 1
Trigger 2
Trigger 3
PXI Star
Trigger 0
Trigger 1
Trigger 2
Trigger 3
PXI Star*
Trigger 0
Trigger 1
Trigger 2
Trigger 3
2
LBLStar0
LBLStar1
LBLStar2
LBLStar3
Slot 3
LBR0
LBR1
LBR2
LBR3
Slot 4
3
1
* A Slot 2 device ties the PXI Star Line to the PXI 10 MHz clock
1 Shared Local Bus Lines between Slot 2 and Slot 3
2 Shared Trigger Lines between Slot 2, Slot 3, and Slot 4
3 Shared Local Bus Lines between Slot 3 and Slot 4
Figure 2-12. PXI Star Trigger Connections in a PXI Chassis
Refer to the PXI Hardware Specification Revision 2.1 and PXI Software
Specification Revision 2.1 at www.pxisa.org for more information about
PXI triggers.
Switch Settings (NI 781xR/783xR Only)
Refer to Figure 2-13 for the location of switches on the NI PCI-781xR and
Figure 2-14 for the location of switches on the NI PXI-781xR. Refer
to Figure 2-15 for the location of switches on the NI PCI-783xR and
Figure 2-16 for the location of switches on the NI PXI-783xR. For normal
operation, SW1 is in the OFF position. To prevent a VI stored in flash
memory from loading to the FPGA at power up, move SW1 to the
ON position, as shown in Figure 2-17.
Note
SW2 and SW3 are not connected.
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SW1, SW2, SW3
Figure 2-13. Switch Location on the NI PCI-781xR
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SW1, SW2, SW3
NI PX
Reconfi I-7811R
gurable
I/O
CONNECTOR 3 (DIO)
CONNECTOR 2 (DIO)
Figure 2-14. Switch Location on the NI PXI-781xR
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SW1, SW2, SW3
Figure 2-15. Switch Location on the NI PCI-783xR
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SW1, SW2, SW3
Figure 2-16. Switch Location on the NI PXI-783xR
ON
ON
1 2 3
a. Normal Operation (Default)
1 2 3
b. Prevent VI From Loading
Figure 2-17. Switch Settings
Complete the following steps to prevent a VI stored in flash memory from
loading to the FPGA:
1.
Power off and unplug the PXI/CompactPCI chassis or PCI computer.
2.
Remove the NI 781xR/783xR from the PXI/CompactPCI chassis or
PCI computer.
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3.
Move SW1 to the ON position, as shown in Figure 2-17b.
4.
Reinsert the NI 781xR/783xR into the PXI/CompactPCI chassis or
PCI computer. Refer to the Installing the Hardware section of the
Getting Started with R Series Intelligent DAQ document for
installation instructions.
5.
Plug in and power on the PXI/CompactPCI chassis or PCI computer.
After completing this procedure, a VI stored in flash memory does not load
to the FPGA at power-on. You can use software to configure the NI 78xxR,
if necessary. To return to the defaults of loading from flash memory, repeat
the previous procedure but return SW1 to the OFF position in step 3. You
can use this switch to enable/disable the ability to load from flash memory.
In addition to this switch, you must configure the NI 78xxR with the
software to autoload an FPGA VI.
Note When the NI 781xR/783xR is powered on with SW1 in the ON position, the analog
circuitry does not return properly calibrated data. Move the switch to the ON position only
while you are using software to reconfigure the NI 781xR/783xR for the desired power-up
behavior. Afterward, return SW1 to the OFF position.
+5 V Power Source
The +5 V terminals on the I/O connector supply +5 V referenced to DGND.
Use these terminals to power external circuitry.
Newer revision NI 781xR/783xR devices have a traditional fuse to
protect the supply from overcurrent conditions. This fuse is not
customer-replaceable; if the fuse permanently opens, return the device
to NI for repair.
Older revision NI 781xR/783xR devices have a self-resetting fuse to protect
the supply from overcurrent conditions. This fuse resets automatically
within a few seconds after the overcurrent condition is removed. For more
information about the self-resetting fuse and precautions to take to
avoid improper connection of +5 V and ground terminals, refer to the
KnowledgeBase document, Self-Resetting Fuse Additional Information,
by going to ni.com/info and entering the info code pptc.
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(NI 784xR/785xR Devices) All NI 784xR/785xR devices have a
user-replaceable socketed fuse to protect the supply from overcurrent
conditions. When an overcurrent condition occurs, check your cabling to
the +5 V terminals and replace the fuse as described in the Device Fuse
Replacement (NI 784xR/785xR Only) section.
Never connect the +5 V power terminals to analog or digital ground or to any
other voltage source on the NI 78xxR device or any other device. Doing so can damage the
device and the computer. NI is not liable for damage resulting from such a connection.
Caution
The power rating on most devices is +4.75 to +5.25 VDC at 1 A.
Refer to the NI R Series Intelligent DAQ Specifications document, available
at ni.com/manuals, to obtain the power rating for your device.
Device Fuse Replacement (NI 784xR/785xR Only)
NI 784xR/785xR devices have a replaceable fuse, Littelfuse part number
0453004 (NI part number 766247-01), that protects the device from
overcurrent through the power connector.
To replace a broken fuse in the NI 784xR/785xR, complete the following
steps:
1.
Power down and unplug the computer or PXI chassis.
2.
Remove the PCI device from the expansion slot on the computer, or
the PXI device from the PXI slot in the PXI chassis.
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3.
Replace the broken fuse while referring to Figure 2-18 for the fuse
locations.
1
1
Littelfuse Part Number 0453 004 (NI Part Number 766247-01)
Figure 2-18. NI 784xR/785xR Replacement Fuse Location
4.
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Reinstall the PCI or PXI device into the computer or PXI chassis.
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Field Wiring Considerations
(NI 783xR/784xR/785xR Only)
Environmental noise can seriously affect the measurement accuracy of the
device if you do not take proper care when running signal wires between
signal sources and the device. The following recommendations mainly
apply to AI signal routing to the device, as well as signal routing in general.
Take the following precautions to minimize noise pickup and maximize
measurement accuracy:
•
Use differential AI connections to reject common-mode noise.
•
Use individually shielded, twisted-pair wires to connect AI signals to
the device. With this type of wire, the signals attached to the positive
and negative inputs are twisted together and then covered with a shield.
You then connect this shield only at one point to the signal source
ground. This kind of connection is required for signals traveling
through areas with large magnetic fields or high electromagnetic
interference.
•
Route signals to the device carefully. Keep cabling away from noise
sources. The most common noise source in a PXI DAQ system is the
video monitor. Keep the monitor and the analog signals as far apart as
possible.
Use the following recommendations for all signal connections to the
NI 783xR/784xR/785xR:
•
Separate NI 783xR/784xR/785xR signal lines from high-current or
high-voltage lines. These lines can induce currents in or voltages on
the NI 783xR/784xR/785xR signal lines if they run in parallel paths at
a close distance. To reduce the magnetic coupling between lines,
separate them by a reasonable distance if they run in parallel or run the
lines at right angles to each other.
•
Do not run signal lines through conduits that also contain power lines.
•
Protect signal lines from magnetic fields caused by electric motors,
welding equipment, breakers, or transformers by running them through
special metal conduits.
Refer to the NI Developer Zone tutorial, Field Wiring and Noise
Considerations for Analog Signals, at ni.com/zone for more information.
© National Instruments Corporation
2-31
R Series Intelligent DAQ User Manual
Calibration
(NI 783xR/784xR/785xR Only)
3
Calibration is the process of determining and/or adjusting the accuracy of
an instrument to minimize measurement and output voltage errors. On the
NI 783xR/784xR/785xR, onboard calibration DACs (CalDACs) correct
these errors. Because the analog circuitry handles calibration, the data read
from the AI channels or written to the AO channels in the FPGA VI is
already calibrated.
Three levels of calibration are available for the NI 783xR/784xR/785xR
to ensure the accuracy of its analog circuitry. The first level, loading
calibration constants, is the fastest, easiest, and least accurate. The
intermediate level, internal calibration, is the preferred method of assuring
accuracy in your application. The last level, external calibration, is the
slowest, most difficult, and most accurate.
Loading Calibration Constants
The NI 783xR/784xR/785xR is factory calibrated before shipment at
approximately 25 °C to the levels indicated in the device specifications.
Refer to the NI R Series Intelligent DAQ Specifications, available at
ni.com/manuals, for more information calibration levels. The onboard
nonvolatile flash memory stores the calibration constants for the device.
Calibration constants are the values that were written to the CalDACs to
achieve calibration in the factory. The NI 783xR/784xR/785xR hardware
reads these constants from the flash memory and loads them into the
CalDACs at power-on. This occurs before you load a VI into the FPGA.
Internal Calibration
With internal calibration, the NI 783xR/784xR/785xR can measure and
correct almost all of its calibration-related errors without any external
signal connections. NI provides software to perform an internal calibration.
This internal calibration process, which generally takes less than
two minutes, is the preferred method of assuring accuracy in your
© National Instruments Corporation
3-1
R Series Intelligent DAQ User Manual
Chapter 3
Calibration (NI 783xR/784xR/785xR Only)
application. Internal calibration minimizes the effects of any offset and
gain drifts, particularly those due to changes in temperature. During the
internal calibration process, the AI and AO channels are compared to the
NI 783xR/784xR/785xR onboard voltage reference. The offset and gain
errors in the analog circuitry are calibrated out by adjusting the CalDACs
to minimize these errors.
Note
The NI 78xxR Calibration Utility does not support NI 781xR devices.
If you have NI-RIO installed, you can find the internal calibration utility at
Start»All Programs»National Instruments»NI-RIO»Calibrate 78xxR
Device. Device is the NI PXI-783xR/784xR/785xR or NI PCI-783xR
device.
Immediately after internal calibration, the only significant residual
calibration error is gain error due to time and temperature drift of the
onboard voltage reference. You can minimize gain errors by performing
an external calibration. If you are primarily taking relative measurements,
then you can ignore a small amount of gain error and self-calibration is
sufficient.
The flash memory on the NI 783xR/784xR/785xR stores the results of an
internal calibration so the CalDACs automatically load with the newly
calculated calibration constants the next time the NI 783xR/784xR/785xR
is powered on.
External Calibration
An external calibration refers to calibrating your device with a known
external reference rather than relying on the onboard reference. The
NI 783xR/784xR/785xR has an onboard calibration reference to ensure
the accuracy of self-calibration. The reference voltage is measured at the
factory and stored in the flash memory for subsequent internal calibrations.
Externally calibrate the device annually or more often if you use it at
extreme temperatures.
During the external calibration process, the onboard reference value is
re-calculated. This compensates for any time or temperature drift-related
errors in the onboard reference that might have occurred since the last
calibration. You can save the results of the external calibration process to
flash memory so that the NI 783xR/784xR/785xR loads the new calibration
constants the next time it is powered on. The device uses the newly
measured onboard reference level for subsequent internal calibrations.
R Series Intelligent DAQ User Manual
3-2
ni.com
Chapter 3
Calibration (NI 783xR/784xR/785xR Only)
To externally calibrate your device, use an external reference several times
more accurate than the device itself. For more information on externally
calibrating your NI 783xR/784xR/785xR device, refer to the NI 783xR
Calibration Procedure for NI-RIO, found on ni.com/manuals.
© National Instruments Corporation
3-3
R Series Intelligent DAQ User Manual
Connecting I/O Signals
A
This appendix describes how to make input and output signal connections
to the NI 78xxR I/O connectors.
Figure A-1 shows the I/O connector pin assignments and locations for
NI PCI-7811R/7813R and NI PXI-7811R/7813R.
Figure A-2 shows the I/O connector pin assignments and locations
for NI PCI-7830R/7831R/7833R and the NI PXI-7830R/7831R/7833R/
7841R/7842R/7851R/7852R/7853R/7854R.
Note
The NI PXI-7830R and NI PCI-7830R do not have Connector 2 (RDIO).
© National Instruments Corporation
A-1
R Series Intelligent DAQ User Manual
DIO35
DIO33
DIO31
DIO29
DIO27
DIO26
DIO25
DIO24
DIO23
DIO22
DIO21
DIO20
DIO19
DIO18
DIO17
DIO16
DIO15
DIO14
DIO13
DIO12
DIO11
DIO10
DIO9
DIO8
DIO7
DIO6
DIO5
DIO4
DIO3
DIO2
DIO1
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
DIO38
DIO36
DIO34
DIO32
DIO30
DIO28
+5V
TERMINAL 68
TERMINAL 35
TERMINAL 34
TERMINAL 1
DGND
TERMINAL 1
TERMINAL 34
DGND
DGND
DGND
TERMINAL 35
TERMINAL 68
TERMINAL 68
TERMINAL 35
TERMINAL 34
TERMINAL 1
TERMINAL 1
TERMINAL 34
TERMINAL 35
TERMINAL 68
+5V
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
CONNECTOR 1
(RDIO)
DIO0
68
67
66
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
CONNECTOR 2
(RDIO)
DIO39
DIO37
CONNECTOR 3
(RDIO)
Connecting I/O Signals
CONNECTOR 0
(RDIO)
Appendix A
Figure A-1. NI 781xR Connector Pin Assignments and Locations
R Series Intelligent DAQ User Manual
A-2
ni.com
Connecting I/O Signals
CONNECTOR 0
(RMIO)
Appendix A
DIO35
DIO33
DIO31
DIO29
DIO27
DIO26
DIO25
DIO24
DIO23
DIO22
DIO21
DIO20
DIO19
DIO18
DIO17
DIO16
DIO15
DIO14
DIO13
DIO12
DIO11
DIO10
DIO9
DIO8
DIO7
DIO6
DIO5
DIO4
DIO3
DIO2
DIO1
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
DIO38
DIO36
DIO34
DIO32
DIO30
DIO28
+5V
AI0+
AIGND0
AI1+
AI2+
AIGND2
AI3+
AI4+1
TERMINAL 68
TERMINAL 34
+5V
DGND
DGND
AIGND4
AI5+1
AI6+1
DGND
DGND
TERMINAL 1
AIGND6
AI7+1
DGND
DGND
DGND
TERMINAL 35
AISENSE
AO0
AO1
DGND
DGND
DGND
AO2
AO3
AO41
AO51
AO61
DGND
DGND
DGND
DGND
DGND
DGND
DGND
TERMINAL 68
TERMINAL 35
TERMINAL 34
TERMINAL 1
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
AO71
DIO15
DIO13
DIO11
DIO9
TERMINAL 1
TERMINAL 34
TERMINAL 35
TERMINAL 68
CONNECTOR 1
(RDIO)
DIO0
68
67
66
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
CONNECTOR 2
(RDIO)
DIO39
DIO37
DIO7
DIO6
DIO5
DIO4
DIO3
DIO2
DIO1
DIO0
+5V
68
67
66
65
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
20
19
18
17
16
15
14
13
12
11
10
9
8
7
6
5
4
3
2
1
AI0–
AIGND1
AI1–
AI2–
AIGND3
AI3–
AI4–1
AIGND5
AI5–1
AI6–1
AIGND7
AI7–1
No Connect
AOGND0
AOGND1
AOGND2
AOGND3
AOGND4
AOGND5
AOGND6
AOGND7
DIO14
DIO12
DIO10
DIO8
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
+5V
1 No Connect on the NI 7830R
Figure A-2. NI 783xR/784xR/785xR Connector Pin Assignments and Locations
© National Instruments Corporation
A-3
R Series Intelligent DAQ User Manual
Appendix A
Connecting I/O Signals
To access the signals on the I/O connectors, you must connect a cable from
the I/O connector to a signal accessory. Plug the small VHDCI connector
end of the cable into the appropriate I/O connector and connect the other
end of the cable to the appropriate signal accessory.
Table A-1. I/O Connector Signal Descriptions
Signal Name
Reference
Direction
Description
DGND
Output
+5 VDC Source—These pins supply 5 V from the computer
power supply. For more information on the +5V terminals,
refer to the +5 V Power Source section in Chapter 2,
Hardware Overview of the NI 78xxR.
+5V
Analog Signals (NI 783xR/784xR/785xR Only)
AI<0..7>+
AIGND
Input
Positive input for Analog Input channels 0 through 7.
AI<0..7>–
AIGND
Input
Negative input for Analog Input channels 0 through 7.
—
—
Analog Input Ground—These pins are the reference point
for single-ended measurements in RSE configuration and
the bias current return point for differential measurements.
All three ground references—AIGND, AOGND, and
DGND—are connected to each other on the
NI 783xR/784xR/785xR.
AISENSE
AIGND
Input
Analog Input Sense—This pin serves as the reference node
for AI <0..7> when the device is configured for NRSE mode.
AO<0..7>
AOGND
Output
Analog Output channels 0 through 7. Each channel can
source or sink up to 2.5 mA.
AOGND
—
—
Analog Output Ground—The analog output voltages
are referenced to this node. All three ground
references—AIGND, AOGND, and DGND—are
connected to each other on the NI 783xR/784xR/785xR.
—
—
Digital Ground—These pins supply the reference for the
digital signals at the I/O connector and the 5 V supply.
All three ground references—AIGND, AOGND, and
DGND—are connected to each other on the
NI 783xR/784xR/785xR.
DGND
Input or
Output
AIGND
Digital Signals (All NI 78xxR Devices)
DGND
DIO<0..39>
Connector<0..3>
(NI 781xR)
Digital I/O signals.
DIO<0..15>
Connector 0
(NI 783xR/784xR/785xR)
DIO<0..39>
Connector <1..2>
(NI 783xR/784xR/785xR)
R Series Intelligent DAQ User Manual
A-4
ni.com
Appendix A
Connecting I/O Signals
Connections that exceed any of the maximum ratings of input or output signals
on the NI 78xxR can damage the NI 78xxR and the computer. Maximum input ratings for
each signal are in the Protection column of Table A-2. NI is not liable for any damage
resulting from such signal connections
Caution
Table A-2. NI 78xxR I/O Signal Summary
Signal Name
+5V
Signal
Type and
Direction
Impedance
Input/
Output
Protection
(Volts)
On/Off
Source
(mA at V)
Sink
(mA at V)
Rise Time
Bias
DO
—
—
—
—
—
—
Analog Signals (NI 783xR/784xR/785xR Only)
AI<0..7>+
AI
10 GΩ in
parallel with
100 pF
42/35
—
—
—
±2 nA
AI<0..7>–
AI
10 GΩ in
parallel with
100 pF
42/35
—
—
—
±2 nA
AIGND
AO
—
—
—
—
—
—
AISENSE
AI
10 GΩ in
parallel with
100 pF
42/35
—
—
—
±2 nA
AO<0..7>
AO
1.25 Ω
Short
circuit to
ground
2.5 at 10
2.5 at –10
10 V/μs
—
AOGND
AO
—
—
—
—
—
—
—
—
—
—
—
—
Digital Signals (All NI 78xxR Devices)
DIO<0..39>
Connector<0..3>
(NI 781xR)
DIO
—
–0.5 to +7.0
(NI 783xR)
4.0 at 2.4
4.0 at 0.4
–20 to 20
(NI 784xR/
NI 785xR)
DIO<0..15>
Connector 0
(NI 783xR,
NI 784xR, and
NI 785xR)
DIO<0..39>
Connector <1..2>
(NI 783xR,
NI 784xR, and
NI 785xR)
AI = Analog Input
AO = Analog Output
© National Instruments Corporation
DIO = Digital Input/Output
A-5
DO = Digital Output
R Series Intelligent DAQ User Manual
Appendix A
Connecting I/O Signals
Connecting to 5B and SSR Analog Signal Conditioning
(NI 783xR/784xR/785xR Only)
NI provides cables that allow you to connect signals from the
NI 783xR/784xR/785xR directly to 5B backplanes for analog signal
conditioning and SSR backplanes for digital signal conditioning.
The NSC68-262650 cable connects the signals on the
NI 783xR/784xR/785xR RMIO connector directly to 5B and SSR
backplanes. This cable has a 68-pin male VHDCI connector on one end that
plugs into the NI 783xR/784xR/785xR RMIO connector. The other end of
this cable provides two 26-pin female headers plus one 50-pin female
header.
One of the 26-pin headers contains all the NI 783xR/784xR/785xR analog
input signals. You can plug this connector directly into a 5B backplane for
analog input signal conditioning. The NI 783xR/784xR/785xR AI<0..n>
correspond to the 5B backplane channels <0..n> in sequential order.
Configure the AI channels to use the NRSE input mode when using
5B signal conditioning.
The other 26-pin header contains all the NI 783xR/784xR/785xR analog
output signals. You can plug this connector directly into a 5B backplane
for AO signal conditioning. The NI 783xR/784xR/785xR AO<0..n>
correspond to the 5B backplane channels <0..n> in sequential order.
The 50-pin header contains the 16 DIO lines available on the
NI 783xR/784xR/785xR RMIO connector. You can plug this header
directly into an SSR backplane for digital signal conditioning. DIO lines
<0..15> correspond to the 5B backplane Slots <0..15> in sequential order.
The 5B connector pinouts are compatible with 8-channel 5B08 backplanes
and 16-channel 5B01 backplanes. The NI 7830R can accept analog
input from the first four channels of a 16-channel backplane.
The NI 7831R/7833R/784xR/785xR can accept analog input from the
first eight channels of a 16-channel backplane. The SSR connector pinout
is compatible with 8-, 16-, 24-, and 32-channel SSR backplanes. You can
connect to an SSR backplane containing a number of channels unequal to
the 16 DIO lines available on the 50-pin header. In this case, you have
access to only the channels that exist on both the SSR backplane and the
NSC68-262650 cable 50-pin header.
R Series Intelligent DAQ User Manual
A-6
ni.com
Appendix A
Connecting I/O Signals
Figure A-3 shows the connector pinouts when using the NSC68-262650
cable.
AO0
AOGND0
AO1
AO2
AOGND2
AO3
AO4
AOGND4
AO5
AO6
AOGND6
AO7
No Connect
1
3
5
7
9
11
13
15
17
19
21
23
25
2
4
6
8
10
12
14
16
18
20
22
24
26
No Connect
No Connect
AOGND1
No Connect
No Connect
AOGND3
No Connect
No Connect
AOGND5
No Connect
No Connect
AOGND7
No Connect
AO 0–7 Connector
Pin Assignment
AI0+
AIGND0
AI1+
AI2+
AIGND2
AI3+
AI4+
AIGND4
AI5+
AI6+
AIGND6
AI7+
AISENSE
1
3
5
7
9
11
13
15
17
19
21
23
25
2
4
6
8
10
12
14
16
18
20
22
24
26
AI0–
AI1–
AIGND1
AI2–
AI3–
AIGND3
AI4–
AI5–
AIGND5
AI6–
AI7–
AIGND7
No Connect
AI 0–7 Connector
Pin Assignment
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
DIO15
DIO14
DIO13
DIO12
DIO11
DIO10
DIO9
DIO8
DIO7
DIO6
DIO5
DIO4
DIO3
DIO2
DIO1
DIO0
+5V
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DIO 0–15 Connector
Pin Assignment
Figure A-3. Connector Pinouts when Using NSC68-262650 Cable
Connecting to SSR Digital Signal Conditioning
NI provides cables that allow you to connect signals from the NI 78xxR
directly to SSR backplanes for digital signal conditioning.
The NSC68-5050 cable connects the signals on the NI 78xxR RDIO
connectors directly to SSR backplanes for digital signal conditioning. This
cable has a 68-pin male VHDCI connector on one end that plugs into the
NI 78xxR RDIO connectors. The other end of this cable provides
two 50-pin female headers.
© National Instruments Corporation
A-7
R Series Intelligent DAQ User Manual
Appendix A
Connecting I/O Signals
You can plug each of these 50-pin headers directly into an 8-, 16-, 24-,
or 32-channel SSR backplane for digital signal conditioning. One of the
50-pin headers contains DIO<0..23> from the NI 78xxR RDIO connector.
These lines correspond to Slots <0..23> on an SSR backplane in sequential
order. The other 50-pin header contains DIO<24..39> from the NI 78xxR
RDIO connector. These lines correspond to Slots <0..15> on an SSR
backplane in sequential order. You can connect to an SSR backplane
containing a number of channels unequal to the number of lines on the
NSC68-5050 cable header. In this case, you have access only to the
channels that exist on both the SSR backplane and the NSC68-5050 cable
header you are using.
Figure A-4 shows the connector pinouts when using the NSC68-5050
cable.
DIO23
DIO22
DIO21
DIO20
DIO19
DIO18
DIO17
DIO16
DIO15
DIO14
DIO13
DIO12
DIO11
DIO10
DIO9
DIO8
DIO7
DIO6
DIO5
DIO4
DIO3
DIO2
DIO1
DIO0
+5V
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
DIO39
DIO38
DIO37
DIO36
DIO35
DIO34
DIO33
DIO32
DIO31
DIO30
DIO29
DIO28
DIO27
DIO26
DIO25
DIO24
+5V
DIO 0–23 Connector
Pin Assignment
1
3
5
7
9
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
2
4
6
8
10
12
14
16
18
20
22
24
26
28
30
32
34
36
38
40
42
44
46
48
50
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
No Connect
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DGND
DIO 24–39 Connector
Pin Assignment
Figure A-4. Connector Pinouts when Using the NSC68-5050 Cable
R Series Intelligent DAQ User Manual
A-8
ni.com
B
Using the SCB-68
Shielded Connector Block
This appendix describes how to connect input and output signals to the
NI 78xxR with the SCB-68 shielded connector block.
The SCB-68 has 68 screw terminals for I/O signal connections. To use
the SCB-68 with the NI 78xxR, you must configure the SCB-68 as a
general-purpose connector block. Refer to Figure B-1 for the
general-purpose switch configuration.
S1
S2
S5 S4 S3
Figure B-1. General-Purpose Switch Configuration for the SCB-68 Terminal Block
After configuring the SCB-68 switches, you can connect the I/O signals to
the SCB-68 screw terminals. Refer to Appendix A, Connecting I/O Signals,
for the connector pin assignments for the NI 78xxR. After connecting
I/O signals to the SCB-68 screw terminals, you can connect the
SCB-68 to the with the SHC68-68-RMIO (for Connector 0 on the
NI 783xR/784xR/785xR) or SHC68-68-RDIO (Connector <0..3> on the
NI 781xR and Connector <1..2> on the NI 783xR/784xR/785xR) shielded
cables.
© National Instruments Corporation
B-1
R Series Intelligent DAQ User Manual
Technical Support and
Professional Services
C
Visit the following sections of the award-winning National Instruments
Web site at ni.com for technical support and professional services:
•
Support—Technical support resources at ni.com/support include
the following:
–
Self-Help Technical Resources—For answers and solutions,
visit ni.com/support for software drivers and updates, a
searchable KnowledgeBase, product manuals, step-by-step
troubleshooting wizards, thousands of example programs,
tutorials, application notes, instrument drivers, and so on.
Registered users also receive access to the NI Discussion Forums
at ni.com/forums. NI Applications Engineers make sure every
question submitted online receives an answer.
–
Standard Service Program Membership—This program
entitles members to direct access to NI Applications Engineers
via phone and email for one-to-one technical support as well as
exclusive access to on demand training modules via the Services
Resource Center. NI offers complementary membership for a full
year after purchase, after which you may renew to continue your
benefits.
For information about other technical support options in your
area, visit ni.com/services, or contact your local office at
ni.com/contact.
•
Training and Certification—Visit ni.com/training for
self-paced training, eLearning virtual classrooms, interactive CDs,
and Certification program information. 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, National Instruments
Alliance Partner members can help. To learn more, call your local
NI office or visit ni.com/alliance.
© National Instruments Corporation
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Appendix C
Technical Support and Professional Services
•
Declaration of Conformity (DoC)—A DoC is our claim of
compliance with the Council of the European Communities using
the manufacturer’s declaration of conformity. This system affords
the user protection for electromagnetic compatibility (EMC) and
product safety. You can obtain the DoC for your product by visiting
ni.com/certification.
•
Calibration Certificate—If your product supports calibration,
you can obtain the calibration certificate for your product at
ni.com/calibration.
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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ni.com
Glossary
Symbol
Prefix
Value
p
pico
10 –12
n
nano
10 –9
µ
micro
10 – 6
m
milli
10 –3
k
kilo
10 3
M
mega
10 6
G
giga
10 9
Numbers/Symbols
°
Degrees.
>
Greater than.
≥
Greater than or equal to.
<
Less than.
≤
Less than or equal to.
–
Negative of, or minus.
Ω
Ohms.
/
Per.
%
Percent.
±
Plus or minus.
+
Positive of, or plus.
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Glossary
Square root of.
+5V
+5 VDC source signal.
A
A
Amperes.
A/D
Analog-to-digital.
AC
Alternating current.
ADC
Analog-to-digital converter—An electronic device, often an integrated
circuit, that converts an analog voltage to a digital number.
AI
Analog input.
AI<i>
Analog input channel signal.
AIGND
Analog input ground signal.
AISENSE
Analog input sense signal.
AO
Analog output.
AO<i>
Analog output channel signal.
AOGND
Analog output ground signal.
ASIC
Application-Specific Integrated Circuit—A proprietary semiconductor
component designed and manufactured to perform a set of specific
functions.
B
bipolar
A signal range that includes both positive and negative values (for example,
–5 to +5 V).
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Glossary
C
C
Celsius.
CalDAC
Calibration DAC.
CH
Channel—Pin or wire lead to which you apply or from which you read the
analog or digital signal. Analog signals can be single-ended or differential.
For digital signals, you group channels to form ports. Ports usually consist
of either four or eight digital channels.
cm
Centimeter.
CMOS
Complementary metal-oxide semiconductor.
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).
common-mode voltage
Any voltage present at the instrumentation amplifier inputs with respect to
amplifier ground.
CompactPCI
Refers to the core specification defined by the PCI Industrial Computer
Manufacturer’s Group (PICMG).
D
D/A
Digital-to-analog.
DAC
Digital-to-analog converter—An electronic device, often an integrated
circuit, that converts a digital number into a corresponding analog voltage
or current.
DAQ
Data acquisition—A system that uses the computer to collect, receive,
and generate electrical signals.
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.
DGND
Digital ground signal.
DIFF
Differential mode.
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Glossary
DIO
Digital input/output.
DIO<i>
Digital input/output channel signal.
DMA
Direct memory access—A method by which data can be 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.
DNL
Differential nonlinearity—A measure in LSB of the worst-case deviation of
code widths from their ideal value of 1 LSB.
DO
Digital output.
E
EEPROM
Electrically erasable programmable read-only memory—ROM that can be
erased with an electrical signal and reprogrammed.
F
FPGA
Field-Programmable Gate Array.
FPGA VI
A configuration that is downloaded to the FPGA and that determines the
functionality of the hardware.
G
glitch
An unwanted signal excursion of short duration that is usually unavoidable.
H
h
Hour.
HIL
Hardware-in-the-loop.
Hz
Hertz.
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Glossary
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.
INL
Relative accuracy.
L
LabVIEW
Laboratory Virtual Instrument Engineering Workbench. LabVIEW is a
graphical programming language that uses icons instead of lines of text to
create programs.
LSB
Least significant bit.
M
m
Meter.
max
Maximum.
MIMO
Multiple input, multiple output.
min
Minimum.
MIO
Multifunction I/O.
monotonicity
A characteristic of a DAC in which the analog output always increases as
the values of the digital code input to it increase.
mux
Multiplexer—A switching device with multiple inputs that sequentially
connects each of its inputs to its output, typically at high speeds, in order to
measure several signals with a single analog input channel.
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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,
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.
NRSE
Nonreferenced single-ended mode—All measurements are made with
respect to a common (NRSE) measurement system reference, but the
voltage at this reference can vary with respect to the measurement system
ground.
O
OUT
Output pin—A counter output pin where the counter can generate various
TTL pulse waveforms.
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 work-stations.
PCI offers a theoretical maximum transfer rate of 132 MB/s.
port
(1) A communications connection on a computer or a remote controller.
(2) A digital port, consisting of four or eight lines of digital input and/or
output.
ppm
Parts per million.
pu
Pull-up.
PWM
Pulse-width modulation.
PXI
PCI eXtensions for Instrumentation—An open specification that builds off
the CompactPCI specification by adding instrumentation-specific features.
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Glossary
R
RAM
Random-access memory—The generic term for the read/write memory that
is used in computers. RAM allows bits and bytes to be written to it as well
as read from. Various types of RAM are DRAM, EDO RAM, SRAM, and
VRAM.
resolution
The smallest signal increment that can be detected by a measurement
system. 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.
RIO
Reconfigurable I/O.
rms
Root mean square.
RSE
Referenced single-ended mode—All measurements are made with respect
to a common reference measurement system or a ground. Also called a
grounded measurement system.
RTSI
Real-time system integration bus—The timing and triggering bus that
connects multiple devices directly. This allows for hardware
synchronization across devices.
S
s
Seconds.
S
Samples.
S/s
Samples per second—Used to express the rate at which a DAQ board
samples an analog signal.
signal conditioning
The manipulation of signals to prepare them for digitizing.
slew rate
The voltage rate of change as a function of time. The maximum slew rate
of an amplifier is often a key specification to its performance. Slew rate
limitations are first seen as distortion at higher signal frequencies.
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Glossary
T
THD
Total harmonic distortion—The ratio of the total rms signal due to
harmonic distortion to the overall rms signal, in decibel or a percentage.
thermocouple
A temperature sensor created by joining two dissimilar metals. The
junction produces a small voltage as a function of the temperature.
TTL
Transistor-transistor logic.
two’s complement
Given a number x expressed in base 2 with n digits to the left of the radix
point, the (base 2) number 2n – x.
V
V
Volts.
VDC
Volts direct current.
VHDCI
Very high density cabled interconnect.
VI
Virtual instrument—Program in LabVIEW that models the appearance and
function of a physical instrument.
VIH
Volts, input high.
VIL
Volts, input low.
VOH
Volts, output high.
VOL
Volts, output low.
Vrms
Volts, root mean square.
W
waveform
Multiple voltage readings taken at a specific sampling rate.
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