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National Instruments NI 7831R User Manual

National Instruments NI 7831R User Manual

Reconfigurable i/o devices for pci/pxi/compactpci bus computers
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Reconfigurable I/O
NI 7831R User Manual
Reconfigurable I/O Devices for
PCI/PXI/CompactPCI Bus Computers
NI 7831R User Manual
April 2004 Edition
Part Number 370489B-01

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  • Page 1 Reconfigurable I/O NI 7831R User Manual Reconfigurable I/O Devices for PCI/PXI/CompactPCI Bus Computers NI 7831R User Manual April 2004 Edition Part Number 370489B-01...
  • Page 2 Thailand 662 992 7519, United Kingdom 44 0 1635 523545 For further support information, refer to the Technical Support and Professional Services appendix. To comment on the documentation, send email to techpubs@ni.com. © 2003–2004 National Instruments Corporation. All rights reserved.

  • Page 3: Important Information

    Warranty The NI 7831R 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.
  • Page 4 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...

  • Page 5: Table Of Contents

    LabVIEW Real-Time Module...1-6 Cables and Optional Equipment ...1-7 Custom Cabling ...1-8 Safety Information ...1-9 Chapter 2 Hardware Overview of the NI 7831R Analog Input ...2-3 Input Modes...2-4 Input Range ...2-4 Connecting Analog Input Signals ...2-5 Types of Signal Sources ...2-7 Floating Signal Sources...2-7...
  • Page 6 Loading Calibration Constants ... 3-1 Internal Calibration... 3-1 External Calibration... 3-2 Appendix A Specifications Appendix B Connecting I/O Signals Appendix C Using the SCB-68 Shielded Connector Block Appendix D Technical Support and Professional Services Glossary NI 7831R User Manual ni.com...

  • Page 7: About This Manual

    National Instruments 7831R device and contains information concerning its operation and programming. The NI 7831R device is a Reconfigurable I/O (RIO) device. The NI 7831R has eight independent, 16-bit analog input (AI) channels, eight independent, 16-bit analog output (AO) channels, and 96 digital I/O (DIO) lines.

  • Page 8: Reconfigurable I/O Documentation

    Reconfigurable I/O Documentation The NI 7831R User Manual is one piece of the documentation set for your RIO system and application. Depending on the hardware and software you use for your application, you could have any of several types of documentation.

  • Page 9: Related Documentation

    • © National Instruments Corporation NI Developer Zone tutorial, Field Wiring and Noise Considerations for Analog Signals, at ni.com/zone PICMG CompactPCI 2.0 R3.0 PXI Hardware Specification Revision 2.1 PXI Software Specification Revision 2.1 About This Manual NI 7831R User Manual...

  • Page 10: Introduction

    16-bit analog input (AI) channels. A user-reconfigurable FPGA (Field-Programmable Gate Array) controls the digital and analog I/O lines on the NI 7831R. The FPGA on the R Series device allows you to define the functionality and timing of the device. You...

  • Page 11: Using Pxi With Compactpci

    PICMG CompactPCI 2.0 R3.0 core specification. PXI-specific features are implemented on the J2 connector of the CompactPCI bus. Table 1-1 lists the J2 pins used by the NI 7831R. The NI 7831R is compatible with any CompactPCI chassis with a sub-bus that does not drive these lines.

  • Page 12: Overview Of Reconfigurable I/O

    I/O resources on the NI 7831R. Reconfigurable I/O Concept The NI 7831R is 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 core to match the requirements of the measurement and control system.

  • Page 13: User-Defined I/O Resources

    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 functions using the LabVIEW FPGA Module. NI 7831R User Manual FPGA Bus Interface Figure 1-1. High-Level FPGA Functional Overview...

  • Page 14: Reconfigurable I/O Applications

    <LabVIEW>\examples\FPGA Software Development You can use LabVIEW with the LabVIEW FPGA Module to program the NI 7831R. To develop real-time applications that control the NI 7831R, you can use LabVIEW with the LabVIEW Real-Time Module. LabVIEW FPGA Module The FPGA Module enables you to use LabVIEW to create VIs that run on the FPGA of the R Series device.

  • Page 15: Labview Real-Time Module

    The LabVIEW Real-Time Module allows you to use the NI 7831R in RT Series PXI systems being controlled in real time by a VI. The NI 7831R plug-in device is designed as a single-point AI, AO, and DIO complement to the LabVIEW Real-Time Module.

  • Page 16: Cables And Optional Equipment

    Cables and Optional Equipment 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 1-2. Cable Cable Description SH68-C68-S Shielded 68-pin VHDCI male connector to female 0.050 series D-type...

  • Page 17: Custom Cabling

    Refer to Custom Cabling NI offers a variety of cables for connecting signals to the NI 7831R. If you need to develop a custom cable, a nonterminated shielded cable is available from NI. The SHC68-NT-S connects to the NI 7831R VHDCI connectors on one end of the cable.

  • Page 18: Safety Information

    Misuse of the NI 7831R can result in a hazard. You can compromise the safety protection built into the NI 7831R if the NI 7831R is damaged in any way. If the NI 7831R is damaged, return it to NI for repair.
  • Page 19 Chapter 1 Introduction Operate the NI 7831R at or below the installation category section Measurement circuits are subjected to working voltages 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.

  • Page 20: Hardware Overview Of The Ni 7831R

    This chapter presents an overview of the hardware functions and I/O connectors on the NI 7831R. Figure 2-1 shows a block diagram for the NI 7831R. Figure 2-2 shows the parts locator diagram for the NI PXI-7831R. Figure 2-3 shows the parts locator diagram for the NI PCI-7831R.
  • Page 21 Chapter 2 Hardware Overview of the NI 7831R Figure 2-2. Parts Locator Diagram for the NI PXI-7831R NI 7831R User Manual ni.com...

  • Page 22: Analog Input

    Analog Input The NI 7831R has eight independent, 16-bit AI channels that you can sample 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.

  • Page 23: Input Modes

    The negative input pin connects to the negative input of the instrumentation amplifier. When the NI 7831R 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.

  • Page 24: Connecting Analog Input Signals

    Table B-2, AIGND is a common AI signal that is routed directly to the ground tie point on the NI 7831R. You can use this signal for a general analog ground tie point to the NI 7831R if necessary.
  • Page 25 You must reference all signals to ground either at the source device or at the NI 7831R. 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 section of this chapter for more information about these input modes.

  • Page 26: Types Of Signal Sources

    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 7831R AIGND through a bias resistor to establish a local or onboard reference for the signal.
  • Page 27 Chapter 2 Hardware Overview of the NI 7831R (Not Connected to Building Ground) Input Differential (DIFF) See text for information on bias resistors. Single-Ended — Ground Referenced (RSE) Single-Ended — Nonreferenced (NRSE) See text for information on bias resistors. NI 7831R User Manual...

  • Page 28: Differential Connection Considerations (Diff Input Mode)

    Differential Connection Considerations (DIFF Input Mode) In DIFF input mode, the NI 7831R 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.

  • Page 29: Differential Connections For Nonreferenced Or Floating Signal Sources

    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 7831R 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.
  • Page 30 © National Instruments Corporation Chapter 2 AI– AISENSE AIGND DIFF Input Mode Selected Figure 2-7. Differential Input Connections for Nonreferenced Signals 2-11 Hardware Overview of the NI 7831R Instrumentation Amplifier Measured – Voltage – x8 Channels NI 7831R User Manual...

  • Page 31: Single-Ended Connection Considerations

    Single-Ended Connection Considerations When the NI 7831R 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.

  • Page 32: Single-Ended Connections For Floating Signal Sources (Rse Input Mode)

    Sources (NRSE Input Mode) To measure a grounded signal source with a single-ended input mode, you must configure the NI 7831R in the NRSE input mode. Then connect the signal to the positive input of the NI 7831R instrumentation amplifier and connect the signal local ground reference to the negative input of the instrumentation amplifier.

  • Page 33: Common-Mode Signal Rejection Considerations

    The instrumentation amplifier rejects this difference. If the input circuitry of a NI 7831R is referenced to ground in RSE input mode, this difference in ground potentials appears as an error in the measured voltage.

  • Page 34: Analog Output

    To set the power-on levels, you can configure the NI 7831R to load and run your VI when the system powers on. This VI can set the AO channels to the desired voltage levels. The VI interprets data written to the DAC in two’s complement format.

  • Page 35: Digital I/O

    When the system powers on, the DIO lines are high-impedance. To set another power-on state, you can configure the NI 7831R to load a VI when the system powers on. This VI can then set the DIO lines to any power-on state.
  • Page 36 Caution Do not short the DIO lines of the NI 7831R directly to power or to ground. Doing so can damage the NI 7831R by causing excessive current to flow through the DIO lines.
  • Page 37 LED shown in Figure 2-11. The NI 7831R SH68-C68-S shielded cable contains 34 twisted pairs of conductors. To maximize the digital I/O available on the NI 7831R, some of the DIO lines are twisted with power or ground and some DIO lines are twisted with other DIO lines.

  • Page 38: Rtsi Trigger Bus

    Slot 2 of the PXI chassis. The PXI star trigger line on the NI PXI-7831R is PXI/STAR. The NI 7831R 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.

  • Page 39: Pxi Local Bus (For Ni Pxi-7831R Only)

    Caution Do not drive the same RTSI trigger bus line with the NI 7831R and another device simultaneously. Such signal driving can damage both devices. NI is not liable for any damage resulting from such signal driving.

  • Page 40: Switch Settings

    Caution Do not configure the NI 7831R and another device to drive the same physical star trigger line simultaneously. Such signal driving can damage the NI 7831R and the other device.

  • Page 41: Power Connections

    Caution other voltage source on the NI 7831R or any other device under any circumstance. Doing so can damage the NI 7831R and the computer. NI is not liable for damage resulting from such a connection. NI 7831R User Manual Reinsert the NI 7831R into the PXI/CompactPCI chassis or PCI computer.

  • Page 42: Field Wiring Considerations

    Separate NI 7831R signal lines from high-current or high-voltage lines. These lines can induce currents in or voltages on the NI 7831R 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.

  • Page 43: Calibration

    AI channels or written to the AO channels in the FPGA VI is already calibrated. Three levels of calibration are available for the NI 7831R 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.

  • Page 44: External Calibration

    The flash memory on the NI 7831R stores the results of an internal calibration so the CalDACs automatically load with the newly calculated calibration constants the next time the NI 7831R is powered on.

  • Page 45: Specifications

    Specifications This appendix lists the specifications of the NI 7831R. These specifications are typical at 25 °C unless otherwise noted. Analog Input Input Characteristics Number of channels ... 8 Input modes... DIFF, RSE, NRSE Type of ADC... Successive approximation Resolution ... 16 bits, 1 in 65,536 Conversion time ...

  • Page 46: Dynamic Characteristics

    DNL ...–1.0 to +2.0 LSB max No missing codes resolution...16 bits typ, 15 bits min CMRR, DC to 60 Hz ...86 dB Dynamic Characteristics Bandwidth System noise ...1.8 LSB NI 7831R User Manual Absolute Accuracy Noise + Quantization (µV) Offset...

  • Page 47: Output Characteristics

    Appendix A Specifications Accuracy 4 LSB 2 LSB µ µ 10.3 µ µ Absolute Accuracy at Temp Drift Full Scale µ (%/°C) (mV) 2366 0.0005 5.88 ± 10 °C of external or factory calibration NI 7831R User Manual µ µ...
  • Page 48 Settling time Slew rate ...10 V/ Noise ...150 Glitch energy at midscale transition ...±200 mV for 3 Digital I/O Number of channels...96 input/output Compatibility ...TTL NI 7831R User Manual Step Size 16 LSB ±20.0 V µ ±2.0 V µ ±0.2 V µ...
  • Page 49 NI PXI-7831R... Onboard clock, phase-locked to Onboard clock... ±100 ppm, 250 ps jitter Appendix A Specifications 0.0 V 0.8 V 2.0 V 5.5 V — 0.4 V 2.4 V — may be shorted at a time) PXI 10 MHz clock NI 7831R User Manual...

  • Page 50: Bus Interface

    Recommended warm-up time...15 minutes Calibration interval ...1 year Onboard calibration reference Note Refer to Calibration Certificates at calibration certificate for the NI 7831R. Bus Interface PXI (NI PXI-7831R only) ...Master, slave PCI (NI PCI-7831R only)...Master, slave Power Requirement +5 VDC (±5%) ...450 mA (typ), 700 mA (max) +3.3 VDC (±5%) ...335 mA (typ), 730 mA (max)

  • Page 51: Operating Environment

    Channel-to-earth... ±12 V, Installation Category I Channel-to-channel ... ±24 V, Installation Category I Environmental The NI 7831R is intended for indoor use only. Operating Environment Using 40 MHz timebase... 0 to 55 °C, tested in accordance Using 80 MHz timebase... 0 to 55 °C in all NI PXI chassis ©...

  • Page 52: Storage Environment

    Shock and Vibration (for NI PXI-7831R Only) Operational Shock ...30 g peak, half-sine, 11 ms pulse Random Vibration NI 7831R User Manual Operating ...5 to 500 Hz, 0.3 g Nonoperating ...5 to 500 Hz, 2.4 g chassis, tested in accordance with...

  • Page 53: Electromagnetic Compatibility

    IEC 61010-1, EN 61010-1 UL 3111-1, UL 61010B-1 CAN/CSA C22.2 No. 1010.1 ni.com/hardref.nsf ni.com/hardref.nsf Appendix A Specifications , search by model number FCC Part 15A above 1 GHz Table 1 (Class A) compliant , search by model NI 7831R User Manual...
  • Page 54 This appendix describes how to make input and output signal connections to the NI 7831R I/O connectors. The NI 7831R has two DIO connectors with 40 DIO lines per connector, and one MIO connector with eight AI lines, eight AO lines, and 16 DIO lines.
  • Page 55 Connecting I/O Signals Figure B-2 shows the I/O connector pin assignments for the I/O connectors on the NI 7831R. The DIO connector pin assignment applies to connectors <1..2> on the NI 7831R. The MIO connector pin assignment applies to connector 0 on the NI 7831R.
  • Page 56 Connections that exceed any of the maximum ratings of input or output signals Caution on the NI 7831R can damage the NI 7831R and the computer. Maximum input ratings for each signal are in the Protection column of Table B-2. NI is not liable for any damage resulting from such signal connections ©...
  • Page 57 Connecting to CompactRIO Extension I/O Chassis You can use the CompactRIO R Series Expansion chassis and CompactRIO I/O modules with the NI 7831R. Refer to the CompactRIO R Series Expansion System Installation Instructions for information about connecting the chassis to the NI 7831R.
  • Page 58 Connecting to 5B and SSR Signal Conditioning NI provides cables that allow you to connect signals from the NI 7831R 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 7831R MIO connector directly to 5B and SSR backplanes.
  • Page 59 SSR backplanes for digital signal conditioning. This cable has a 68-pin male VHDCI connector on one end that plugs into the NI 7831R DIO connectors. The other end of this cable provides two 50-pin female headers. You can plug each of these 50-pin headers directly into an 8-, 16-, 24-, or 32-channel SSR backplane for digital signal conditioning.
  • Page 60 Appendix B Connecting I/O Signals DIO39 DIO38 DIO37 DIO36 DIO35 DIO34 DIO33 DIO32 DGND DIO31 DGND DIO30 DGND DIO29 DGND DIO28 DGND DIO27 DGND DIO26 DGND DIO25 DGND DIO24 DGND DGND DIO 24–39 Connector Pin Assignment NI 7831R User Manual...
  • Page 61 NI 7831R 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 7831R, you must configure the SCB-68 as a general-purpose connector block. Refer to Figure C-1 for the general-purpose switch configuration.
  • Page 62 Technical Support and Professional Services Visit the following sections of the National Instruments Web site at ni.com • • • • • © National Instruments Corporation for technical support and professional services: Support—Online technical support resources at include the following: –...
  • Page 63 You also can visit the Worldwide Offices section of office Web sites, which provide up-to-date contact information, support phone numbers, email addresses, and current events. NI 7831R User Manual and could not find the answers you need, contact ni.com ni.com/niglobal to access the branch ni.com...
  • Page 64 < Less than. ≤ Less than or equal to. – Negative of, or minus. Ω Ohms. Per. Percent. ± Plus or minus. Positive of, or plus. © National Instruments Corporation Value –12 –9 – 6 –3 NI 7831R User Manual...
  • Page 65 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). NI 7831R User Manual © National Instruments Corporation...
  • Page 66 Decibel—The unit for expressing a logarithmic measure of the ratio of two signal levels: dB = 20log10 V1/V2, for signals in volts. Direct current. DGND Digital ground signal. DIFF Differential mode. © National Instruments Corporation Glossary NI 7831R User Manual...
  • Page 67 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. Hour. Hardware-in-the-loop. Hertz. NI 7831R User Manual © National Instruments Corporation...
  • Page 68 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. © National Instruments Corporation Glossary NI 7831R User Manual...
  • Page 69 (2) A digital port, consisting of four or eight lines of digital input and/or output. Parts per million. Pull-up. Pulse-width modulation. PCI eXtensions for Instrumentation—An open specification that builds off the CompactPCI specification by adding instrumentation-specific features. NI 7831R User Manual © National Instruments Corporation...
  • Page 70 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. © National Instruments Corporation Glossary NI 7831R User Manual...
  • Page 71 Virtual instrument—Program in LabVIEW that models the appearance and function of a physical instrument. 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. NI 7831R User Manual © National Instruments Corporation...

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