National Instruments NI 785xR, NI 784xR User Manual

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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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The NI 7811R/7813R/7830R/7831R/7833R/7841R/7842R/7851R/7852R/7853R/7854R is warranted against defects in materials and workmanship for a period of one year from the date of shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace equipment that proves to be defective during the warranty period. This warranty includes parts and labor.

The media on which you receive National Instruments software are warranted not to fail to execute programming instructions, due to defects in materials and workmanship, for a period of 90 days from date of shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace software media that do not execute programming instruc tions if National Instruments receives notice of such defects during the warranty period. National Instruments does not warrant that the operation of the software shall be uninterrupted or error free.

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Compliance

Compliance with FCC/Canada Radio Frequency Interference Regulations

Determining FCC Class

The Federal Communications Commission (FCC) has rules to protect wireless communications from interference. The FCC places digital electronics into two classes. These classes are known as Class A (for use in industrial-commercial locations only) or Class B (for use in residential or commercial locations). All National Instruments (NI) products are FCC Class A products.

Depending on where it is operated, this Class A product could be subject to restrictions in the FCC rules. (In Canada, the Department of Communications (DOC), of Industry Canada, regulates wireless interference in much the same way.) Digital electronics emit weak signals during normal operation that can affect radio, television, or other wireless products.

All Class A products display a simple warning statement of one paragraph in length regarding interference and undesired operation. The FCC rules have restrictions regarding the locations where FCC Class A products can be operated.

Consult the FCC Web site at

FCC/DOC Warnings

This equipment generates and uses radio frequency energy and, if not installed and used in strict accordance with the instructions in this manual and the CE marking Declaration of Conformity*, may cause interference to radio and television reception. Classification requirements are the same for the Federal Communications Commission (FCC) and the Canadian Department of Communications (DOC).

Changes or modifications not expressly approved by NI could void the user’s authority to operate the equipment under the FCC Rules.

Class A

Federal Communications Commission

This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to part 15 of the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio frequency energy and, if not installed and used in accordance with the instruction manual, may cause harmful interference to radio communications. Operation of this equipment in a residential area is likely to cause harmful interference in which case the user is required to correct the interference at their own expense.

www.fcc.gov for more information.

Canadian Department of Communications

This Class A digital apparatus meets all requirements of the Canadian Interference-Causing Equipment Regulations. Cet appareil numérique de la classe A respecte toutes les exigences du Règlement sur le matériel brouilleur du Canada.

Compliance with EU Directives

Users in the European Union (EU) should refer to the Declaration of Conformity (DoC) for information* pertaining to the CE marking. Refer to the Declaration of Conformity (DoC) for this product for any additional regulatory compliance information. To obtain the DoC for this product, visit and click the appropriate link in the Certification column.

* The CE marking Declaration of Conformity contains important supplementary information and instructions for the user or

installer.

ni.com/certification, search by model number or product line,

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

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

Flexible Functionality .......................................................................1-4

User-Defined I/O Resources .............................................................1-4

Device-Embedded Logic and Processing .........................................1-4

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

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/783x R Only) ............................................................... 2-21

Switch Settings (NI 781xR/783x R Only)...................................................................... 2-23

+5 V Power Source........................................................................................................ 2-28

Device Fuse Replacement (NI 784xR/785x R Only) ...................................... 2-29

Field Wiring Considerations (NI 783x R/784x R/785xR Only) ..................................... 2-31

Chapter 3 Calibration (NI 783x R/784x R/785x ROnly)

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

R Series Intelligent DAQ User Manual vi 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.

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 78xxRNI781xR, 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.

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

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.

R Series Intelligent DAQ User Manual 1-2 ni.com

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 78x xR, 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.

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.

R Series Intelligent DAQ User Manual 1-4 ni.com

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.

Chapter 1 Introduction

Fixed I/O Resource

FPGA

Bus Interface

Figure 1-1. High-Level FPGA Functional Overview

Fixed I/O Resource

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.

Chapter 1 Introduction

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.

R Series Intelligent DAQ User Manual 1-6 ni.com

Note 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.

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.

Chapter 1 Introduction

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.

Chapter 1 Introduction

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 Description

SHC68-68-RMIO (NI Recommended)

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.

SHC68-68-RDIO (NI Recommended)

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.

SH68-C68-S 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.

CAT 5 Ethernet crossover cable

— — 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.

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.

R Series Intelligent DAQ User Manual 1-8 ni.com

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.

Chapter 1 Introduction

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.

Chapter 1 Introduction

• 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 category hardware label. Measurement circuits are subjected to working voltages

marked on the

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:

• Measurement Category I is for measurements performed on circuits not directly connected to the electrical distribution system referred to as MAINS

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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Chapter 1 Introduction

• 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.

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)

Connector 0 (DIO) Connector 1 (DIO) Connector 2 (DIO) Connector 3 (DIO)

Digital I/O (40)

User-Configurable

FPGA on

RIO Devices

Configuration Control

Configuration

Data/Address/Control

PXI Local Bus (NI PXI-781x R Only)

RTSI Bus

Flash Memory

Bus

Interface

Control

Address/Data

PCI/PXI/CompactPCI Bus

RTSI/PXI Triggers

Figure 2-1. NI 781xR Block Diagram

Chapter 2 Hardware Overview of the NI 78xxR

Input Mode Mux

AISENSE AIGND

Calibration

Connector 0 (MIO)

Connector 1 (DIO)

AI+

AI–

Mux

Input Mux

Voltage

Reference

16-Bit

DAC

Digital I/O (16)

Digital I/O (40)

Instrumentation Ampliflier

–

x4 Channels

Temperature

Sensor

Calibration

DACs

x4 Channels

Calibration

DACs

16-Bit

ADC

Configuration

Control

Configuration

User-

Configurable

FPGA on RIO

Data/Address/

Control

Devices

Figure 2-2. NI 7830R Block Diagram

Flash

Memory

Bus

Interface

PXI Local Bus (NI PXI-7830R only)

RTSI Bus

Control

Address/Data

PCI/PXI/CompactPCI Bus

RTSI/PXI Triggers

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Input Mode Mux

AISENSE AIGND

Calibration

Connector 0 (MIO)

Connector 1 (DIO)Connector 2 (DIO)

AI+

AI–

Mux

Input Mux

Voltage

Reference

16-Bit

DAC

Digital I/O (16)

Digital I/O (40)

Instrumentation Amplifier

–

x8 Channels

Temperature

Sensor

Calibration

DACs

x8 Channels

Calibration

DACs

16-Bit

ADC

User-

Configurable

FPGA on RIO

Devices

Chapter 2 Hardware Overview of the NI 78xx R

Configuration

Control

Configuration

Data/Address/

Control

Flash

Memory

Bus

Interface

Control

Address/Data

PCI/PXI/CompactPCI Bus

PXI Local Bus (NI PXI-783xR only)

RTSI Bu s

Digital I/O (40)

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.

RTSI/PXI Triggers

Figure 2-3. NI 7831R/7833R/784xR/785xR Block Diagram

Chapter 2 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 784x R 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 785x R 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

Output Code (Hex)

Input Description AI Voltage

Full-scale range –1 LSB 9.999695 7FFF

Full-scale range –2 LSB 9.999390 7FFE

Midscale 0.000000 0000

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(Two’s Complement)

Chapter 2 Hardware Overview of the NI 78xx R

Table 2-1. Ideal Output Code and AI Voltage Mapping (Continued)

Output Code (Hex)

Input Description AI Voltage

Negative full-scale range +1 LSB –9.999695 8001

Negative full-scale range –10.000000 8000

(Two’s Complement)

Any input voltage —

Output Code

---------------------------------32,768

10.0 V×

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

Input Range

The NI 783xR/784xR/785xR AI range is fixed at ±10 V.

Chapter 2 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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Chapter 2 Hardware Overview of the NI 78xx R

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.

in+

in–

Instrumentation

Amplifier

–

= [V

in+

– V

in–

]

Measured

Voltage

–

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.

Chapter 2 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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Chapter 2 Hardware Overview of the NI 78xx R

Figure 2-5 summarizes the recommended input mode for both types of signal sources.

Signal Source Type

Input

Differential

(DIFF)

Single-Ended—

Ground

Referenced

(RSE)

Floating Signal Source

(Not Connected to Building Ground)

Examples

• Ungrounded Thermocouples

• Signal Conditioning with Isolated Outputs

• Battery Devices

–

AI(+)

AI(–)

–

AIGND

See text for information on bias resistors.

–

AI

AIGND

–

Grounded Signal Source

Examples

• Plug-in Instruments with Nonisolated Outputs

–

AI(+)

AI(–)

–

AIGND

NOT RECOMMENDED

–

+ V

–

AIGND

Ground-loop losses, Vg, are added to

measured signal.

AI

AISENSE

–

AIGND

Single-Ended—

Nonreferenced

(NRSE)

AI

–

AISENSE

–

AIGND

–

See text for information on bias resistors.

Figure 2-5. Summary of Analog Input Connections

Chapter 2 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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Chapter 2 Hardware Overview of the NI 78xx R

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.

Ground-

Referenced

Signal

Source

Common-

Mode

Noise and

Ground

Potential

–

I/O Connector

AI+

AI–

AISENSE

AIGND

DIFF Input Mode Selected

Instrumentation

Amplifier

–

Measured

Voltage

–

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 V

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+

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.

Chapter 2 Hardware Overview of the NI 78xxR

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

Bias

Current

Return

Path s

Bias Resistors

(see text)

–

I/O Connector

AI+

AI–

AISENSE

AIGND

DIFF Input Mode Selected

Instrumentation

Amplifier

–

Measured

Vol ta ge

–

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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Chapter 2 Hardware Overview of the NI 78xx R

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 3m(10ft).

• The input signal can share a common reference point with other signals.

Chapter 2 Hardware Overview of the NI 78xxR

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.

Floating

Signal

Source

–

I/O Connector

AI+

AI–

AISENSE

AIGND

RSE Input Mode Selected

Instrumentation

Amplifier

–

Measured

Voltage

–

Figure 2-8. Single-Ended Input Connections for Nonreferenced or Floating Signals

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Chapter 2 Hardware Overview of the NI 78xx R

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.

Ground-

Referenced

Signal

Source

Common-

Mode

Noise and

Ground

Potential

–

I/O Connector

AI+

AI–

AISENSE

AIGND

NRSE Input Mode Selected

Instrumentation

Amplifier

–

Measured

Voltage

–

Figure 2-9. Single-Ended Input Connections for Ground-Referenced Signals

Chapter 2 Hardware Overview of the NI 78xxR

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+ (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.

and V–in

Table 2-3. Ideal Output Voltage and Input Code Mapping

Input Code (Hex)

Output Description AO Voltage

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

Any output voltage —

Note If your VI does not set the output value for an AO channel, then the AO channel

voltage output will be undefined.

R Series Intelligent DAQ User Manual 2-16 ni.com

(Two’s Complement)

AO Voltage

-------------------------------

10.0 V

32,768×

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.

Chapter 2 Hardware Overview of the NI 78xx R

Load

VOUT 0

–

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

AO0

AOGND0

Channel 0

NI 783xR/784xR/785xR

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

Chapter 2 Hardware Overview of the NI 78xxR

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 783x R/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 specifications.

ni.com/manuals, for detailed DIO

Caution 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.

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.

R Series Intelligent DAQ User Manual 2-18 ni.com

LED

5 V CMOS

DGND

†

+5 V

TTL or LVCMOS Compatible Devices

Chapter 2 Hardware Overview of the NI 78xx R

DIO<4..7>

TTL, LVTTL, CMOS, or LVCMOS Signal

+5 V

Switch

I/O Connector

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.

DIO<0..3>

DGND

NI 783xR/784xR/785xR

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.

Chapter 2 Hardware Overview of the NI 78xxR

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 Digital Lines

SH68-C68-S

Shielded Cable

Signal Pairing

Recommended Types

of Digital Signals

NI 781xR 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

NI 783xR, NI 784xR, NI 785xR

DIO<28..39> DIO line paired

with another DIO line

Connector 0, DIO<0..7>; Connector 1, DIO<0..27>; Connector 2, DIO<0..27>

DIO line paired with power or ground

Static signals or non-edge-sensitive, low-frequency signals

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>

R Series Intelligent DAQ User Manual 2-20 ni.com

DIO line paired with another DIO line

Static signals or non-edge-sensitive, low-frequency signals

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.

Chapter 2 Hardware Overview of the NI 78xx R

Caution 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.

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 PXI triggers.

www.pxisa.org for more information about

PXI Local Bus (NI PXI-781xR/783x R 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.

Chapter 2 Hardware Overview of the NI 78xxR

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.

Caution 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.

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.

Caution 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.

R Series Intelligent DAQ User Manual 2-22 ni.com

Chapter 2 Hardware Overview of the NI 78xx R

PXI Star*

LBLStar0 LBLStar1 LBLStar2 LBLStar3

Trigger 0

Trigger 1

Slot 2

Trigger 2

Trigger 3

LBR0 LBR1 LBR2 LBR3

PXI Star

LBLStar0 LBLStar1 LBLStar2 LBLStar3

Trigger 0

Trigger 1

Trigger 2

Trigger 3

Slot 3

LBR0 LBR1 LBR2 LBR3

PXI Star

LBLStar0 LBLStar1 LBLStar2 LBLStar3

* 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 3Shared 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 781x R/783x R 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.

Trigger 0

Trigger 1

Slot 4

Trigger 2

Trigger 3

LBR0 LBR1 LBR2 LBR3

Note SW2 and SW3 are not connected.

Chapter 2 Hardware Overview of the NI 78xxR

SW1, SW2, SW3

Figure 2-13. Switch Location on the NI PCI-781xR

R Series Intelligent DAQ User Manual 2-24 ni.com

NI PXI-

Reconfigurab

7811R

Chapter 2 Hardware Overview of the NI 78xx R

SW1, SW2, SW3

le I/O

CONNECTOR 2 (DIO)CONNECTOR 3 (DIO)

Figure 2-14. Switch Location on the NI PXI-781xR

Chapter 2 Hardware Overview of the NI 78xxR

SW1, SW2, SW3

Figure 2-15. Switch Location on the NI PCI-783xR

R Series Intelligent DAQ User Manual 2-26 ni.com

Chapter 2 Hardware Overview of the NI 78xx R

SW1, SW2, SW3

Figure 2-16. Switch Location on the NI PXI-783xR

123

a. Normal Operation (Default) b. Prevent VI From Loading

Figure 2-17. Switch Settings

123

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.

Chapter 2 Hardware Overview of the NI 78xxR

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

R Series Intelligent DAQ User Manual 2-28 ni.com

ni.com/info and entering the info code pptc.

Chapter 2 Hardware Overview of the NI 78xx R

(NI 784x R/785x R 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/785x R Only) section.

Caution 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.

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

ni.com/manuals, to obtain the power rating for your device.

Device Fuse Replacement (NI 784x R/785x R 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.

Chapter 2 Hardware Overview of the NI 78xxR

3. Replace the broken fuse while referring to Figure 2-18 for the fuse locations.

1 Littelfuse Part Number 0453 004 (NI Part Number 766247-01)

Figure 2-18. NI 784xR/785xR Replacement Fuse Location

4. Reinstall the PCI or PXI device into the computer or PXI chassis.

R Series Intelligent DAQ User Manual 2-30 ni.com

Field Wiring Considerations (NI 783x R/784x R/785xROnly)

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.

Chapter 2 Hardware Overview of the NI 78xx R

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.

Calibration (NI 783x R/784x R/785xROnly)

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

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/784x R/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.

Connecting I/O Signals

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).

Appendix A Connecting I/O Signals

(RDIO)

CONNECTOR 0

(RDIO)

CONNECTOR 3

DIO39 DIO37

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

DIO0

68 34

67 33

66 32

65 31

64 30

63 29

62 28

61 27

60 26

59 25

58 24

57 23

56 22

55 21

54 20

53 19

52 18

51 17

50 16

49 15

48 14

47 13

46 12

45 11

44 10

43 9

42 8

41 7

40 6

39 5

38 4

37 3

36 2

35 1

DIO38 DIO36

DIO34

DIO32 DIO30

DIO28

+5V

DGND DGND

DGND

DGND DGND DGND

DGND DGND

DGND

DGND DGND

DGND

DGND DGND

DGND

DGND DGND

DGND

TERMINAL 68

TERMINAL 34

TERMINAL 1

TERMINAL 35

TERMINAL 68

TERMINAL 34

TERMINAL 1

TERMINAL 35

TERMINAL 1

TERMINAL 34

TERMINAL 68

TERMINAL 35

TERMINAL 1

TERMINAL 34

TERMINAL 68

(RDIO)

CONNECTOR 1

CONNECTOR 2

Figure A-1. NI 781xR Connector Pin Assignments and Locations

R Series Intelligent DAQ User Manual A-2 ni.com

(RMIO)

CONNECTOR 0

Appendix A Connecting I/O Signals

DIO39 DIO37

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

DIO0

68 34

67 33

66 32

65 31

64 30

63 29

62 28

61 27

60 26

59 25

58 24

57 23

56 22

55 21

54 20

53 19

52 18

51 17

50 16

49 15

48 14

47 13

46 12

45 11

44 10

43 9

42 8

41 7

40 6

39 5

38 4

37 3

36 2

35 1

DIO38 DIO36

DIO34

DIO32 DIO30

DIO28

+5V

DGND DGND

DGND

DGND DGND DGND

DGND DGND

DGND

DGND DGND

DGND

DGND DGND

DGND

DGND DGND

DGND

TERMINAL 68

TERMINAL 34

TERMINAL 1

TERMINAL 35

TERMINAL 68

TERMINAL 34

TERMINAL 1

TERMINAL 35

TERMINAL 1

TERMINAL 34

TERMINAL 68

AI0+

AIGND0

AI1+

AI2+

AIGND2

AI3+

AI4+

AIGND4

AI5+ AI6+

AIGND6

AI7+

AISENSE

AO0

AO1

AO2 AO3

AO4

AO5 AO6

AO7 DIO15

DIO13

DIO11

DIO9

DIO7

DIO6

DIO5 DIO4 DIO3

DIO2 DIO1 DIO0

+5V

68 34

67 33

66 32

65 31

64 30

63 29

62 28

61 27

60 26

59 25

58 24

57 23

56 22

55 21

54 20

53 19

52 18

51 17

50 16

49 15

48 14

47 13

46 12

45 11

44 10

43 9

42 8

41 7

40 6

39 5

38 4

37 3

36 2

35 1

AI0– AIGND1

AI1–

AI2–

AIGND3 AI3–

AI4–

AIGND5

AI5–

AI6–

AIGND7

AI7–

No Connect AOGND 0 AOGND 1

AOGND 2 AOGND 3

AOGND 4

AOGND 5 AOGND 6

AOGND 7

DIO14

DIO12 DIO10

DIO8

DGND DGND

DGND

+5V

No Connect on the NI 7830R

(RDIO)

CONNECTOR 1

CONNECTOR 2

Figure A-2. NI 783xR/784xR/785xR Connector Pin Assignments and Locations

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

+5V 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 78xx R.

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.

AIGND — — 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> AOG ND 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

Digital Signals (All NI 78xxR Devices)

DGND — — Digital Ground—These pins supply the reference for the

DIO<0..39> Connector<0..3> (NI 781xR)

DIO<0..15> Connector 0 (NI 783xR/784xR/785xR)

DIO<0..39> Connector <1..2> (NI 783xR/784xR/785xR)

DGND Input or

Output

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 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.

Digital I/O signals.

R Series Intelligent DAQ User Manual A-4 ni.com

Appendix A Connecting I/O Signals

Caution 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

Table A-2. NI 78xxR I/O Signal Summary

Signal

Type and

Signal Name

+5V DO — — — — — —

Analog Signals (NI 783xR/784xR/785xR Only)

AI<0..7>+ AI 10 GΩ in

AI<0..7>– AI 10 GΩ in

AIGND AO — — — — — —

AISENSE AI 10 GΩ in

AO<0..7> AO 1.25 Ω Short

AOGND AO — — — — — —

Digital Signals (All NI 78xxR Devices) — — — —

DIO<0..39> Connector<0..3> (NI 781xR)

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 DIO = Digital Input/Output DO = Digital Output

Direction

DIO — –0.5 to +7.0

Impedance

Input/

Output

parallel with

100 pF

parallel with

100 pF

parallel with

100 pF

Protection

(Volts)

On/Off

42/35 — — — ±2 nA

circuit to

ground

(NI 783xR)

–20 to 20 (NI 784xR/ NI 785xR)

Source

(mA at V)

2.5 at 10 2.5 at –10 10 V/μs —

4.0 at 2.4 4.0 at 0.4 — —

Sink

(mA at V)

Rise Time Bias

Appendix A Connecting I/O Signals

Connecting to 5B and SSR Analog Signal Conditioning (NI 783x R/784x R/785x R 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

AOGND0

AOGND2

AOGND4

AOGND6

Connect

AO0

AO1 AO2

AO3 AO4

AO5 AO6

AO7

11 13 15 17 19 21 23 25

1 3 5 7 9

2 4 6

8 10 12 14 16 18 20 22 24 26

Appendix A Connecting I/O Signals

Figure A-3 shows the connector pinouts when using the NSC68-262650 cable.

11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

No No

28 30

No No

DGND

Connect

No AOGND1 No

Connect

AOGND3 No

Connect

AOGND5 No

Connect

AOGND7 No

Connect

AI0+

AIGND0

AI1+ AI2+

AIGND2

AI3+ AI4+

AIGND4

AI5+ AI6+

AIGND6

AI7+

AISENSE

11 13 15 17 19 21 23 25

Connect

No No

Connect Connect

Connect

No No

Connect Connect

DIO15 DIO14 DIO13 DIO12

AI0–

AI1–

AIGND1

AI2–

AI3–

AIGND3

AI4–

AI5–

AIGND5

AI6–

AI7–

AIGND7

Connect

DIO11 DIO10

DIO9 DIO8 DIO7 DIO6 DIO5 DIO4 DIO3 DIO2 DIO1 DIO0

+5V

Connect Connect Connect Connect Connect Connect Connect Connect Connect Connect Connect Connect Connect Connect Connect Connect Connect

AO 0–7 Connector

Pin Assignment

AI 0–7 Connector

Pin Assignment

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.

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.

+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

DIO23 DIO22 DIO21 DIO20 DIO19 DIO18 DIO17 DIO16 DIO15 DIO14 DIO13 DIO12 DIO11 DIO10

DIO9 DIO8 DIO7 DIO6 DIO5 DIO4 DIO3 DIO2 DIO1 DIO0

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

11 13 15 17 19 21 23 25 27 29 31 33 35 37 39 41 43 45 47 49

1 3 5 7 9

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 0–23 Connector

Pin Assignment

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

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.

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.

Technical Support and Professional Services

Visit the following sections of the award-winning National Instruments Web site at

• Support—Technical support resources at

• Training and Certification—Visit

• System Integration—If you have time constraints, limited in-house

ni.com for technical support and professional services:

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/contact.

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.

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/services, or contact your local office at

ni.com/alliance.

ni.com/support include

ni.com/training for

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.

R Series Intelligent DAQ User Manual C-2 ni.com

Glossary

Symbol Prefix Value

ppico10

nnano10

µ micro 10

m milli 10

k kilo 10

Mmega10

Ggiga10

Numbers/Symbols

° Degrees.

> Greater than.

–12

–9

–6

–3

≥ 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.

Glossary

+5V +5 VDC source signal.

Square root of.

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 Analog input channel signal.

AIGND Analog input ground signal.

AISENSE Analog input sense signal.

AO Analog output.

AO 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.

bipolar A signal range that includes both positive and negative values (for example,

–5 to +5 V).

Glossary

CCelsius.

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/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.

Glossary

DIO Digital input/output.

DIO 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.

EEPROM Electrically erasable programmable read-only memory—ROM that can be

erased with an electrical signal and reprogrammed.

FPGA Field-Programmable Gate Array.

FPGA VI A configuration that is downloaded to the FPGA and that determines the

functionality of the hardware.

glitch An unwanted signal excursion of short duration that is usually unavoidable.

hHour.

HIL Hardware-in-the-loop.

Hz Hertz.

Glossary

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.

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 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.

Glossary

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.

OUT Output pin—A counter output pin where the counter can generate various

TTL pulse waveforms.

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.

Glossary

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 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.

Glossary

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 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.

rms

Volts, input high.

Volts, input low.

Volts, output high.

Volts, output low.

Volts, root mean square.

waveform Multiple voltage readings taken at a specific sampling rate.

National Instruments NI 785xR, NI 784xR User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

NI R Series Intelligent DAQ User Manual

Support

Worldwide Technical Support and Product Information

National Instruments Corporate Headquarters

Worldwide Offices

Important Information

Warranty

Copyright

Trademarks

Patents

WARNING REGARDING USE OF NATIONAL INSTRUMENTS PRODUCTS

Compliance

Contents

About This Manual

Conventions

Related Documentation

Reconfigurable I/O Documentation

Additional Resources

About the Reconfigurable I/O Device

Table 1-1. NI 78xxR R Series Intelligent DAQ RIO Device Overview

Using PXI with CompactPCI

Table 1-2. Pins Used by the NI PXI-78xxR

Overview of Reconfigurable I/O

Reconfigurable I/O Concept

Flexible Functionality

User-Defined I/O Resources

Device-Embedded Logic and Processing

Reconfigurable I/O Architecture

Figure 1-1. High-Level FPGA Functional Overview

Reconfigurable I/O Applications

Software Development

LabVIEW FPGA Module

LabVIEW Real-Time Module

Cables and Accessories

Table 1-3. R Series Connectivity Options

Custom Cabling

Safety Information

Figure 2-1. NI 781xR Block Diagram

Figure 2-2. NI 7830R Block Diagram

NI 7811R Overview

NI 7813R Overview

NI 7830R Overview

Figure 2-3. NI 7831R/7833R/784xR/785xR Block Diagram

NI 7831R/7833R Overview

NI 784x R Overview

NI 785x R Overview

Analog Input (Multifunction R Series Only)

Table 2-1. Ideal Output Code and AI Voltage Mapping

Input Modes

Table 2-2. Available Input Modes for the NI 783xR/784xR/785xR

Input Range

Connecting Analog Input Signals

Figure 2-4. NI 783xR/784xR/785xR Instrumentation Amplifier

Types of Signal Sources

Floating Signal Sources

Ground-Referenced Signal Sources

Input Modes

Figure 2-5. Summary of Analog Input Connections

Differential Connection Considerations (DIFF Input Mode)

Differential Connections for Ground-Referenced Signal Sources

Figure 2-6. Differential Input Connections for Ground-Referenced Signals

Differential Connections for Nonreferenced or Floating Signal Sources

Figure 2-7. Differential Input Connections for Nonreferenced Signals

Single-Ended Connection Considerations

Single-Ended Connections for Floating Signal Sources (RSE Input Mode)

Figure 2-8. Single-Ended Input Connections for Nonreferenced or Floating Signals

Single-Ended Connections for Grounded Signal Sources (NRSE Input Mode)

Figure 2-9. Single-Ended Input Connections for Ground-Referenced Signals

Common-Mode Signal Rejection Considerations

Analog Output

Table 2-3. Ideal Output Voltage and Input Code Mapping

Connecting Analog Output Signals

Figure 2-10. Analog Output Connections

Digital I/O

Connecting Digital I/O Signals

Figure 2-11. Example Digital I/O Connections