National Instruments PCI-1200 User Manual

DAQ

PCI-1200 User Manual

Multifunctional I/O Board for PCI Bus Computers

PCI-1200 User Manual

July 1998 Edition

Part Number 320942C-01

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Important Information

Warranty

The PCI-1200 is warranted against defects in materials and workmanship for a period of one year from the date of shipment, as evidenced by receipts or other documentation. National Instruments will, at its option, repair or replace equipment that proves to be defective during the warranty period. This warranty includes parts and labor.

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

A Return Material Authorization (RMA) number must be obtained from the factory and clearly marked on the outside of the package before any equipment will be accepted for warranty work. National Instruments will pay the shipping costs of returning to the owner parts which are covered by warranty.

National Instruments believes that the information in this manual is accurate. The document has been carefully reviewed for technical accuracy. In the event that technical or typographical errors exist, National Instruments reserves the right to make changes to subsequent editions of this document without prior notice to holders of this edition. The reader should consult National Instruments if errors are suspected. In no event shall National Instruments be liable for any damages arising out of or related to this document or the information contained in it.

XCEPT AS SPECIFIED HEREIN

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BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE

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OR INCIDENTAL OR CONSEQUENTIAL DAMAGES, EVEN IF ADVISED OF THE POSSIBILITY THEREOF

National Instruments will apply regardless of the form of action, whether in contract or tort, including negligence. Any action against National Instruments must be brought within one year after the cause of action accrues. National Instruments shall not be liable for any delay in performance due to causes beyond its reasonable control. The warranty provided herein does not cover damages, defects, malfunctions, or service failures caused by owner’s failure to follow the National Instruments installation, operation, or maintenance instructions; owner’s modification of the product; owner’s abuse, misuse, or negligent acts; and power failure or surges, fire, flood, accident, actions of third parties, or other events outside reasonable control.

ATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA, PROFITS, USE OF PRODUCTS

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Trademarks

ComponentWorks™, CVI™, LabVIEW™, Measure™, MITE™, NI-DAQ™, SCXI™, and VirtualBench™ are trademark of National Instruments Corporation.

Product and company names listed are trademarks or trade names of their respective companies.

WARNING REGARDING MEDICAL AND CLINICAL USE OF NATIONAL INSTRUMENTS PRODUCTS

National Instruments products are not designed with components and testing intended to ensure a level of reliability suitable for use in treatment and diagnosis of humans. Applications of National Instruments products involving medical or clinical treatment can create a potential for accidental injury caused by product failure, or by errors on the part of the user or application designer. Any use or application of National Instruments products for or involving medical or clinical treatment must be performed by properly trained and qualified medical personnel, and all traditional medical safeguards, equipment, and procedures that are appropriate in the particular situation to prevent serious injury or death should always continue to be used when National Instruments products are being used. National Instruments products are NOT intended to be a substitute for any form of established process, procedure, or equipment used to monitor or safeguard human health and safety in medical or clinical treatment.

About This Manual

Organization of This Manual.........................................................................................ix

Conventions Used in This Manual.................................................................................x

National Instruments Documentation ............................................................................xi

Related Documentation..................................................................................................xii

Customer Communication .............................................................................................xii

Chapter 1 Introduction

About the PCI-1200.......................................................................................................1-1

What You Need to Get Started ......................................................................................1-1

Unpacking......................................................................................................................1-2

Software Programming Choices ....................................................................................1-2

National Instruments Application Software....................................................1-2

NI-DAQ Driver Software................................................................................1-3

Optional Equipment.......................................................................................................1-5

Custom Cabling .............................................................................................................1-5

Chapter 2 Installation and Configuration

Software Installation ......................................................................................................2-1

Hardware Installation.....................................................................................................2-1

Board Configuration ......................................................................................................2-2

Analog I/O Configuration................................................................................2-2

Analog Output Polarity .....................................................................2-3

Analog Input Polarity........................................................................2-3

Analog Input Mode ...........................................................................2-3

RSE Input (Eight Channels, Reset Condition) ...................2-4

NRSE Input (Eight Channels) ............................................2-4

DIFF Input (Four Channels) ...............................................2-5

Chapter 3 Signal Connections

I/O Connector ................................................................................................................3-1

Signal Connection Descriptions ......................................................................3-2

Analog Input Signal Connections....................................................................3-5

Contents

Types of Signal Sources ................................................................... 3-7

Floating Signal Sources...................................................... 3-7

Ground-Referenced Signal Sources ................................... 3-7

Input Configurations......................................................................... 3-7

Differential Connection Considerations

(DIFF Configuration) ...................................................... 3-9

Differential Connections for Grounded Signal Sources..... 3-10

Differential Connections for Floating Signal Sources ....... 3-11

Single-Ended Connection Considerations.......................... 3-12

Single-Ended Connections for Floating Signal Sources

(RSE Configuration)........................................................ 3-13

Single-Ended Connections for Grounded Signal Sources

(NRSE Configuration)..................................................... 3-13

Common-Mode Signal Rejection Considerations.............. 3-14

Analog Output Signal Connections................................................................. 3-15

Digital I/O Signal Connections ....................................................................... 3-16

Logical Inputs and Outputs............................................................... 3-17

Port C Pin Connections..................................................................... 3-18

Power Connections ......................................................................................... 3-18

DAQ and General Purpose Timing Signal Connections................................. 3-18

DAQ Timing Connections................................................................ 3-19

General Purpose Timing Signal Connections................................... 3-23

Timing Specifications....................................................................... 3-27

Mode 1 Input Timing........................................................................ 3-28

Mode 1 Output Timing..................................................................... 3-29

Mode 2 Bidirectional Timing ........................................................... 3-30

Chapter 4 Theory of Operation

Functional Overview ..................................................................................................... 4-1

PCI Interface Circuitry ..................................................................................................4-2

Timing ........................................................................................................................... 4-3

Analog Input.................................................................................................................. 4-5

Analog Input Circuitry.................................................................................... 4-6

DAQ Operations ............................................................................................. 4-7

Controlled Acquisition Mode ...........................................................4-8

Freerun Acquisition Mode................................................................ 4-8

Interval Scanning Acquisition Mode................................................ 4-8

Single-Channel Data Acquisition ..................................................... 4-9

Multichannel Scanned Data Acquisition .......................................... 4-9

DAQ Rates ...................................................................................................... 4-10

Analog Output ............................................................................................................... 4-11

PCI-1200 User Manual vi © National Instruments Corporation

Analog Output Circuitry..................................................................................4-11

DAC Timing....................................................................................................4-12

Digital I/O ......................................................................................................................4-12

Chapter 5 Calibration

Calibration at Higher Gains ...........................................................................................5-2

Calibration Equipment Requirements............................................................................5-2

Using the Calibration Function......................................................................................5-3

Appendix A Specifications

Appendix B Customer Communication

Glossary

Index

Contents

Figures

Figure 1-1. The Relationship between the Programming Environment,

NI-DAQ, and Your Hardware...............................................................1-4

Figure 3-1. PCI-1200 I/O Connector Pin Assignments ...........................................3-2

Figure 3-2. PCI-1200 Instrumentation Amplifier ....................................................3-6

Figure 3-3. Differential Input Connections for Grounded Signal Sources ..............3-10

Figure 3-4. Differential Input Connections for Floating Sources ............................3-11

Figure 3-5. Single-Ended Input Connections for Floating Signal Sources..............3-13

Figure 3-6. Single-Ended Input Connections for Grounded Signal Sources ...........3-14

Figure 3-7. Analog Output Signal Connections.......................................................3-16

Figure 3-8. Digital I/O Connections.........................................................................3-17

Figure 3-9. EXTCONV* Signal Timing..................................................................3-19

Figure 3-10. Posttrigger DAQ Timing.......................................................................3-20

Figure 3-11. Pretrigger DAQ Timing.........................................................................3-21

Figure 3-12. Interval-Scanning Signal Timing ..........................................................3-22

Figure 3-13. EXTUPDATE* Signal Timing for Updating DAC Output ..................3-23

Figure 3-14. Event-Counting Application with External Switch Gating...................3-24

Figure 3-15. Frequency Measurement Application ...................................................3-25

Contents

Tables

Figure 3-16. General Purpose Timing Signals .......................................................... 3-26

Figure 3-17. Mode 1 Timing Specifications for Input Transfers............................... 3-28

Figure 3-18. Mode 1 Timing Specifications for Output Transfers............................ 3-29

Figure 3-19. Mode 2 Timing Specifications for Bidirectional Transfers .................. 3-30

Figure 4-1. PCI-1200 Block Diagram ..................................................................... 4-1

Figure 4-2. PCI Interface Circuitry.......................................................................... 4-2

Figure 4-3. Timing Circuitry ................................................................................... 4-4

Figure 4-4. Analog Input Circuitry.......................................................................... 4-5

Figure 4-5. Analog Output Circuitry ....................................................................... 4-11

Figure 4-6. Digital I/O Circuitry.............................................................................. 4-12

Table 2-1. Analog I/O Settings............................................................................... 2-2

Table 2-2. Analog Input Modes for the PCI-1200 ................................................. 2-4

Table 3-1. Signal Descriptions for PCI-1200 I/O Connector Pins ........................ 3-3

Table 3-2. Bipolar Analog Input Signal Range Versus Gain................................. 3-5

Table 3-3. Unipolar Analog Input Signal Range Versus Gain............................... 3-5

Table 3-4. Summary of Analog Input Connections ............................................... 3-8

Table 3-5. Port C Signal Assignments ................................................................... 3-18

Table 3-6. Signal Names Used in Timing Diagrams ............................................. 3-27

Table 4-1. Analog Input Settling Time Versus Gain.............................................. 4-10

Table 4-2. PCI-1200 Maximum Recommended DAQ Rates................................. 4-10

PCI-1200 User Manual viii © National Instruments Corporation

About This Manual

This manual describes the electrical and mechanical aspects of the PCI-1200 and contains information concerning its operation and programming.

The PCI-1200 is a low-cost multifunction analog, digital, and timing board. The PCI-1200 is a member of the National Instruments PCI Series of expansion boards for PCI bus computers. These boards are designed for high-performance data acquisition (DAQ) and control for applications in laboratory testing, production testing, and industrial process monitoring and control.

Organization of This Manual

The PCI-1200 User Manual is organized as follows:

• Chapter 1, Introduction, describes the PCI-1200, lists what you need to get started, software programming choices, and optional equipment, and explains how to build custom cables and unpack the PCI-1200.

• Chapter 2, Installation and Configuration, describes how to install and configure your PCI-1200.

• Chapter 3, Signal Connections, describes how to make input and output signal connections to the PCI-1200 board via the board I/O connector and details the I/O timing specifications.

• Chapter 4, Theory of Operation, explains the operation of each functional unit of the PCI-1200.

• Chapter 5, Calibration, discusses the calibration procedures for the PCI-1200 analog I/O circuitry.

• Appendix A, Specifications, lists the PCI-1200 specifications.

• Appendix B, Customer Communication, contains forms you can use to

request help from National Instruments or to comment on our products.

• The Glossary contains an alphabetical list and description of terms used in this manual, including abbreviations, acronyms, definitions, metric prefixes, mnemonics, and symbols.

• The Index contains an alphabetical list of key terms and topics in this manual, including the page where you can find each one.

About This Manual

Conventions Used in This Manual

The following conventions are used in this manual:

<> Angle brackets enclose the name of a key on the keyboard—for example,

<shift>. Angle brackets containing numbers separated by an ellipsis represent a range of values associated with a bit or signal name—for example, DBIO<3..0>.

This icon to the left of bold italicized text denotes a note, which alerts you to important information.

bold Bold text denotes the names of menus, menu items, or dialog box buttons

bold italic Bold italic text denotes a note, caution, or warning.

italic Italic text denotes variables, emphasis, a cross reference, or an introduction

Macintosh Macintosh refers to all Macintosh computers with PCI bus, unless

monospace

PC PC refers to all IBM PC/XT, PC/AT and compatible computers with

This icon to the left of bold italicized text denotes a caution, which advises you of precautions to take to avoid injury, data loss, or a system crash.

This icon to the left of bold italicized text denotes a warning, which advises you of precautions to take to avoid being electrically shocked.

or options.

to a key concept.

otherwise noted.

Text in this font denotes text or characters that you should literally enter from the keyboard, sections of code, programming examples, and syntax examples. This font is also used for the proper names of disk drives, paths, directories, programs, subprograms, subroutines, device names, functions, operations, variables, filenames and extensions, and for statements and comments taken from programs.

PCI bus, unless otherwise noted.

NI-DAQ NI-DAQ is used in this manual to refer to the NI-DAQ software for PC or

Macintosh computers, unless otherwise noted.

SCXI SCXI stands for Signal Conditioning eXtensions for Instrumentation and is

a National Instruments product line designed to perform front-end signal conditioning for National Instruments plug-in DAQ boards.

PCI-1200 User Manual x © National Instruments Corporation

National Instruments Documentation

The PCI-1200 User Manual is one piece of the documentation set for your DAQ system. You could have any of several types of manuals, depending on the hardware and software in your system. Use the manuals you have as follows:

• Getting Started with SCXI—If you are using SCXI, this is the first manual you should read. It gives an overview of the SCXI system and contains the most commonly needed information for the modules, chassis, and software.

• Your SCXI hardware user manuals—If you are using SCXI, read these manuals next for detailed information about signal connections and module configuration. They also explain in greater detail how the module works and contain application hints.

• Your DAQ hardware user manuals—These manuals have detailed information about the DAQ hardware that plugs into or is connected to your computer. Use these manuals for hardware installation and configuration instructions, specification information about your DAQ hardware, and application hints.

• Software documentation—Examples of software documentation you may have are the LabVIEW or LabWindows/CVI documentation sets and the NI-DAQ documentation. After you set up your hardware system, use either the application software (LabVIEW or LabWindows/CVI) or the NI-DAQ documentation to help you write your application. If you have a large and complicated system, it is worthwhile to look through the software documentation before you configure your hardware.

• Accessory installation guides or manuals—If you are using accessory products, read the terminal block and cable assembly installation guides and accessory board user manuals. They explain how to physically connect the relevant pieces of the system. Consult these guides when you are making your connections.

• SCXI Chassis Manual—If you are using SCXI, read this manual for maintenance information on the chassis and installation instructions.

About This Manual

Customer Communication

National Instruments wants to receive your comments on our products and manuals. We are interested in the applications you develop with our products, and we want to help if you have problems with them. To make it easy for you to contact us, this manual contains comment and configuration forms for you to complete. These forms are in Appendix B, Customer

Communication, at the end of this manual.

PCI-1200 User Manual xii © National Instruments Corporation

Introduction

This chapter describes the PCI-1200, lists what you need to get started, software programming choices, and optional equipment, and explains how to build custom cables and unpack the PCI-1200.

About the PCI-1200

Thank you for purchasing the PCI-1200, a low-cost, high-performance multifunction analog, digital, and timing board for PCI bus computers. The PCI-1200 has eight analog input channels that you can configure as eight single-ended or four differential inputs; a 12-bit successive-approximation ADC; two 12-bit DACs with voltage outputs; 24 lines of TTL-compatible digital I/O; and three 16-bit counter/timers for timing I/O.

The PCI-1200 is a member of the National Instruments PCI Series of expansion boards for PCI bus computers. These boards are designed for high-performance data acquisition and control for applications in laboratory testing, production testing, and industrial process monitoring and control.

Detailed PCI-1200 specifications are in Appendix A, Specifications.

What You Need to Get Started

To set up and use your PCI-1200, you will need the following:

PCI-1200 board

❑

PCI-1200 User Manual

❑

One of the following software packages and documentation:

❑

– ComponentWorks

– LabVIEW for Macintosh

– LabVIEW for Windows

– LabWindows/CVI for Windows

– Measure

Chapter 1 Introduction

Unpacking

– NI-DAQ for Macintosh

– NI-DAQ for PC compatibles

– VirtualBench

Your computer

❑

Your PCI-1200 is shipped in an antistatic package to prevent electrostatic damage to the board. Electrostatic discharge can damage several components on the board. To avoid such damage in handling the board, take the following precautions:

• Ground yourself via a grounding strap or by holding a grounded object.

• Touch the antistatic package to a metal part of your computer chassis

before removing the board from the package.

• Remove the board from the package and inspect the board for loose components or any other sign of damage. Notify National Instruments if the board appears damaged in any way. Do not install a damaged board into your computer.

• Never touch the exposed pins of connectors.

Software Programming Choices

There are several options to choose from when programming your National Instruments DAQ or SCXI hardware. You can use LabVIEW, LabWindows/CVI, ComponentWorks, VirtualBench, NI-DAQ, or register-level programming.

National Instruments Application Software

ComponentWorks contains tools for data acquisition and instrument control built on NI-DAQ driver software. ComponentWorks provides a higher-level programming interface for building virtual instruments through standard OLE controls and DLLs. With ComponentWorks, you can use all of the configuration tools, resource management utilities, and interactive control utilities included with NI-DAQ.

LabVIEW features interactive graphics, a state-of-the-art user interface, and a powerful graphical programming language. The LabVIEW Data Acquisition Virtual Instrument (VI) Library, a series of VIs for using LabVIEW with National Instruments DAQ hardware, is included with

PCI-1200 User Manual 1-2 © National Instruments Corporation

LabVIEW. The LabVIEW Data Acquisition VI Library is functionally equivalent to the NI-DAQ software.

LabWindows/CVI features interactive graphics, a state-of-the-art user interface, and uses the ANSI standard C programming language. The LabWindows/CVI Data Acquisition Library, a series of functions for using LabWindows/CVI with National Instruments DAQ hardware, is included with the NI-DAQ software kit. The LabWindows/CVI Data Acquisition Library is functionally equivalent to the NI-DAQ software.

VirtualBench features VIs that combine DAQ products, software, and your computer to create a stand-alone instrument with the added benefit of the processing, display, and storage capabilities of your computer. VirtualBench instruments load and save waveform data to disk in the same forms that can be used in popular spreadsheet programs and word processors.

Using ComponentWorks, LabVIEW, LabWindows/CVI, or VirtualBench software will greatly reduce the development time for your data acquisition and control application.

NI-DAQ Driver Software

The NI-DAQ driver software is included at no charge with all National Instruments DAQ hardware. NI-DAQ is not packaged with SCXI or accessory products, except for the SCXI-1200. NI-DAQ has an extensive library of functions that you can call from your application programming environment. These functions include routines for analog input (A/D conversion), buffered data acquisition (high-speed A/D conversion), analog output (D/A conversion), waveform generation (timed D/A conversion), digital I/O, counter/timer operations, SCXI, RTSI, self-calibration, messaging, and acquiring data to memory.

Chapter 1 Introduction

NI-DAQ has both high-level DAQ I/O functions for maximum ease of use and low-level DAQ I/O functions for maximum flexibility and performance. Examples of high-level functions are streaming data to disk or acquiring a certain number of data points. An example of a low-level function is writing directly to registers on the DAQ device. NI-DAQ does not sacrifice the performance of National Instruments DAQ devices because it lets multiple devices operate at their peak performance.

NI-DAQ also internally addresses many of the complex issues between the computer and the DAQ hardware such as programming interrupts and DMA controllers. NI-DAQ maintains a consistent software interface among its different versions so that you can change platforms with

Chapter 1 Introduction

minimal modifications to your code. Whether you are using conventional programming languages, LabVIEW, LabWindows/CVI, or other application software, your application uses the NI-DAQ driver software, as illustrated in Figure 1-1.

Programming Environment

SCXI Hardware

Figure 1-1.

Register-Level Programming

The final option for programming any National Instruments DAQ hardware is to write register-level software. Writing register-level programming software can be very time-consuming and inefficient, and is not recommended for most users.

Conventional

NI-DAQ

Driver Software

DAQ or

The Relationship between the Programming Environment,

NI-DAQ, and Your Hardware

ComponentWorks,

LabVIEW,

LabWindows/CVI, or

VirtualBench

Personal

Computer or

Workstation

Even if you are an experienced register-level programmer, consider using NI-DAQ, LabVIEW, LabWindows/CVI or other National Instruments application software to program your National Instruments DAQ hardware. Using the National Instruments application software is easier than, and as flexible as, register-level programming, and can save weeks of development time.

PCI-1200 User Manual 1-4 © National Instruments Corporation

Optional Equipment

National Instruments offers a variety of products to use with your PCI-1200 board, including cables, connector blocks, and other accessories, as follows:

• Cables and cable assemblies

• Connector blocks, 50-pin screw terminals

• SCXI modules and accessories for isolating, amplifying, exciting, and

multiplexing signals for relays and analog output. With SCXI you can condition and acquire up to 3,072 channels. To use the PCI-1200 with SCXI you need the SCXI-1341 adapter.

• Low channel count signal conditioning modules, boards, and accessories, including conditioning for strain gauges and RTDs, simultaneous sample and hold, and relays

For more information about optional equipment available from National Instruments, refer to your National Instruments catalogue or call the office nearest you.

Custom Cabling

Chapter 1 Introduction

National Instruments offers cables and accessories for you to prototype your application or to use if you frequently change board interconnections.

If you want to develop your own cable, however, the following guidelines may be useful:

• For the analog input signals, shielded twisted-pair wires for each analog input pair yield the best results, assuming that you use differential inputs. Tie the shield for each signal pair to the ground reference at the source.

• You should route the analog lines separately from the digital lines.

• When using a cable shield, use separate shields for the analog and

digital halves of the cable. Failure to do so results in noise coupling into the analog signals from transient digital signals.

Chapter 1 Introduction

The mating connector for the PCI-1200 is a 50-position, polarized, ribbon socket connector with strain relief. National Instruments uses a polarized (keyed) connector to prevent inadvertent upside-down connection to the PCI-1200. Recommended manufacturer part numbers for this mating connector are as follows:

• Electronic Products Division/3M (part number 3425-7650)

• T&B/Ansley Corporation (part number 609-5041CE)

PCI-1200 User Manual 1-6 © National Instruments Corporation

Installation and Configuration

This chapter describes how to install and configure your PCI-1200.

Software Installation

If you are using NI-DAQ, or National Instruments application software, refer to the installation instructions in your software documentation to install and configure your software.

If you are a register-level programmer, refer to the PCI-1200 Register-Level

Programmer Manual.

Hardware Installation

The PCI-1200 can be installed in any unused PCI expansion slot in your computer.

The following are general installation instructions. Consult the user manual or technical reference manual for your computer for specific instructions and warnings.

1. Turn off your computer.

2. Remove the top cover or access port to the I/O channel.

3. Remove the expansion slot cover on the back panel of the computer.

4. Insert the PCI-1200 in an unused 5 V PCI slot. The fit may be tight, but do not force the board into place.

5. Screw the PCI-1200 mounting bracket to the back panel rail of the computer or use the slot side tabs, if available, to secure the PCI-1200 in place.

6. Replace the top cover on the computer.

The PCI-1200 board is installed.

Chapter 2 Installation and Configuration

Board Configuration

The PCI-1200 is completely software configurable. The PCI-1200 is fully compliant with the PCI Local Bus Specification, Revision 2.0. Therefore, all board resources are automatically allocated by the system. For the PCI-1200, this allocation includes the base memory address and interrupt level. You do not need to perform any configuration steps after the system powers up.

Analog I/O Configuration

Upon power-up or after a software reset, the PCI-1200 is set to the following configuration:

• Referenced single-ended input mode

• ±5 V analog input range (bipolar)

• ±5 V analog output range (bipolar)

Table 2-1 lists all the available analog I/O configurations for the PCI-1200 and shows the configuration in reset condition.

Table 2-1.

Parameter Configuration

Analog Output CH0 Polarity Bipolar—±5 V (reset condition)

Analog Output CH1 Polarity Bipolar—±5 V (reset condition)

Analog Input Polarity Bipolar—±5 V (reset condition)

Analog Input Mode Referenced single-ended (RSE) (reset condition)

Both the analog input and analog output circuitries are software configurable. Refer to your software documentation for more information on changing these settings.

Analog I/O Settings

Unipolar—0 to 10 V

Nonreferenced single-ended (NRSE) Differential (DIFF)

PCI-1200 User Manual 2-2 © National Instruments Corporation

Chapter 2 Installation and Configuration

Analog Output Polarity

The PCI-1200 has two channels of analog output voltage at the I/O connector. You can configure each analog output channel for either unipolar or bipolar output. A unipolar configuration has a range of 0 to 10 V at the analog output. A bipolar configuration has a range of –5 to +5 V at the analog output. In addition, you can select the coding scheme for each D/A converter (DAC) as either two’s complement or straight binary. If you select a bipolar range for a DAC, the two’s complement coding is recommended. In this mode, data values written to the analog output channel range from F800 hex (–2,048 decimal) to 7FF hex (2,047 decimal). If you select a unipolar range for a DAC, the straight binary coding is recommended. In this mode, data values written to the analog output channel range from 0 to FFF hex (4,095 decimal).

Analog Input Polarity

You can select the analog input on the PCI-1200 for either a unipolar range (0 to 10 V) or a bipolar range (–5 to +5 V). In addition, you can select the coding scheme for analog input as either two’s complement or straight binary. If you select a bipolar range, the two’s complement coding is recommended. In this mode, –5 V input corresponds to F800 hex (–2,048 decimal) and +5 V corresponds to 7FF hex (2,047 decimal). If you select a unipolar mode, the straight binary coding is recommended. In this mode, 0 V input corresponds to 0 hex, and +10 V corresponds to FFF hex (4,095 decimal).

Analog Input Mode

The PCI-1200 has three different input modes—RSE input, NRSE input, and DIFF input. The single-ended input configurations use eight channels. The DIFF input configuration uses four channels. Table 2-2 describes these configurations.

Chapter 2 Installation and Configuration

Table 2-2.

Analog Input Modes for the PCI-1200

Analog Input

Modes

Description

RSE RSE mode provides eight single-ended inputs with

the negative input of the instrumentation amplifier referenced to analog ground (reset condition).

NRSE NRSE mode provides eight single-ended inputs with

the negative input of the instrumentation amplifier tied to AISENSE/AIGND and not connected to ground.

DIFF DIFF mode provides four differential inputs with the

positive input of the instrumentation amplifier tied to channels 0, 2, 4, or 6 and the negative input tied to channels 1, 3, 5, or 7, respectively, thus choosing channel pairs (0, 1), (2, 3), (4, 5), or (6, 7).

While reading the following paragraphs, you may find it helpful to refer to the Analog Input Signal Connections section of Chapter 3, Signal

Connections, which contains diagrams showing the signal paths for the

three configurations.

RSE Input (Eight Channels, Reset Condition)

RSE input means that all input signals are referenced to a common ground point that is also tied to the PCI-1200 analog input ground. The differential amplifier negative input is tied to analog ground. The RSE configuration is useful for measuring floating signal sources. With this input configuration, the PCI-1200 can monitor eight different analog input channels.

Considerations for using the RSE configuration are discussed in Chapter 3,

Signal Connections. Notice that in this mode, the signal return path is

analog ground at the connector through the AISENSE/AIGND pin.

NRSE Input (Eight Channels)

NRSE input means that all input signals are referenced to the same common-mode voltage, which floats with respect to the PCI-1200 analog ground. This common-mode voltage is subsequently subtracted by the input instrumentation amplifier. The NRSE configuration is useful for measuring ground-referenced signal sources.

PCI-1200 User Manual 2-4 © National Instruments Corporation

Chapter 2 Installation and Configuration

Considerations for using the NRSE configuration are discussed in Chapter 3, Signal Connections. Notice that in this mode, the signal return path is through the negative terminal of the amplifier at the connector through the AISENSE/AIGND pin.

DIFF Input (Four Channels)

DIFF input means that each input signal has its own reference, and the difference between each signal and its reference is measured. The signal and its reference are each assigned an input channel. With this input configuration, the PCI-1200 can monitor four differential analog input signals.

Considerations for using the DIFF configuration are discussed in Chapter 3, Signal Connections. Notice that the signal return path is through the amplifier’s negative terminal and through channel 1, 3, 5, or 7, depending on which channel pair you select.

Signal Connections

This chapter describes how to make input and output signal connections to the PCI-1200 board via the board I/O connector and details the I/O timing specifications.

The I/O connector for the PCI-1200 has 50 pins that you can connect to 50-pin accessories.

I/O Connector

Figure 3-1 shows the pin assignments for the PCI-1200 I/O connector.

Caution

Connections that exceed any of the maximum ratings of input or output signals on the PCI-1200 may damage the PCI-1200 and the computer. This includes connecting any power signals to ground and vice versa. You should not externally drive digital I/O lines while the computer is powered off; doing so can damage the computer. National Instruments is signal connections that exceed these maximum ratings.

liable for any damages resulting from

NOT

Chapter 3 Signal Connections

ACH0

ACH2 ACH4

ACH6

AISENSE/AIGND

AGND

DGND

PA1

PA3

PA5 PA7

PB1

PB3

PB5

PB7

PC1

PC3 PC5

PC7

EXTUPDATE*

OUTB0 OUTB1

CLKB1

GATB2

+5 V

910

11 12

13 14

15 16

17 18

19 20

21 22

23 24

25 26

27 28

29 30

31 32

33 34

35 36

37 38

39 40

41 42

43 44

45 46

47 48

49 50

ACH1 ACH3

ACH5

ACH7

DAC0OUT

DAC1OUT

PA0

PA2

PA4

PA6 PB0

PB2

PB4

PB6

PC0

PC2

PC4

PC6

EXTTRIG

EXTCONV* GATB0

GATB1

OUTB2

CLKB2

DGND

Figure 3-1.

PCI-1200 I/O Connector Pin Assignments

Signal Connection Descriptions

The following table describes the connector pins on the PCI-1200 I/O connector by pin number and gives the signal name and description of each signal connector pin.

Chapter 3 Signal Connections

Table 3-1.

Signal Descriptions for PCI-1200 I/O Connector Pins

Pin Signal Name Direction Reference Description

1-8 ACH<7..0> AI AGND Analog Channel 7 through 0—Analog

input channels 0 through 7.

9 AISENSE/AIGND I/O AGND Analog Input Sense/Analog Input

Ground—Connected to AGND in RSE mode, analog input sense in NRSE mode.

10 DAC0OUT AO AGND Digital-to-Analog Converter 0

Output—Voltage output signal for analog output channel 0.

11 AGND N/A N/A Analog Ground—Analog output ground

reference for analog output voltages. Bias current return point for differential measurements.

12 DAC1OUT AO AGND Digital-to-Analog Converter 1

Output—Voltage output signal for analog output channel 1.

13, 50

DGND N/A N/A Digital Ground—Voltage ground

reference for the digital signals and the +5 V supply.

14-21 PA<7..0> DIO DGND Port A 7 through 0—Bidirectional data

lines for port A. PA7 is the MSB, and PA0 is the LSB.

22-29 PB<7..0> DIO DGND Port B 7 through 0—Bidirectional data

lines for port B. PB7 is the MSB, and PB0 is the LSB.

30-37 PC<7..0> DIO DGND Port C 7 through 0—Bidirectional data

lines for port C. PC7 is the MSB, and PC0 is the LSB.

38 EXTTRIG DI DGND External Trigger—External control

signal to trigger a DAQ operation.

39 EXTUPDATE* DI DGND External Update—External control

signal to update DAC outputs.

Chapter 3 Signal Connections

Table 3-1.

Signal Descriptions for PCI-1200 I/O Connector Pins (Continued)

Pin Signal Name Direction Reference Description

40 EXTCONV* DIO DGND External Convert—External control

signal to time A/D conversions (DI) and drive SCANCLK when you use SCXI (DO).

41 OUTB0 DO DGND Output B0—Digital output signal of

counter B0.

42 GATB0 DI DGND Gate B0—External control signal for

gating counter B0.

43 OUTB1 DIO DGND Output B1—Digital output signal of

counter B1 (DO). External control signal for timing a scan interval (DI).

44 GATB1 DI DGND Gate B1—External control signal for

gating counter B1.

45 CLKB1 DI DGND Clock B1—External control clock

signal for counter B1.

46 OUTB2 DO DGND Counter B2—Digital output signal of

counter B2.

47 GATB2 DI DGND Gate B2—External control signal for

gating counter B2.

48 CLKB2 DI DGND Clock B2—External control clock

signal for counter B2.

49 +5 V DO DGND +5 Volts—This pin is fused for up to 1 A

of +4.65 to +5.25 V.

* Indicates that the signal is active low.

AI = Analog Input DI = Digital Input DIO = Digital Input/Output AO = Analog Output DO = Digital Output N/A = Not Applicable

The connector pins are grouped into analog input signal pins, analog output signal pins, digital I/O signal pins, timing I/O signal pins, and power connections. The following sections describe the signal connection guidelines for each of these groups.

Analog Input Signal Connections

Pins 1 through 8 are analog input signal pins for the 12-bit ADC. Pin 9, AISENSE/AIGND, is an analog common signal. You can use this pin for a general analog power ground tie to the PCI-1200 in RSE mode or as a return path in NRSE mode. Pin 11, AGND, is the bias current return point for differential measurements. Pins 1 through 8 are tied to the eight single-ended analog input channels of the input multiplexer through 4.7 kΩ series resistors. Pins 2, 4, 6, and 8 and also tied to an input multiplexer for DIFF mode.

The signal ranges for inputs ACH<7..0> at all possible gains are shown in Tables 3-2 and 3-3. Exceeding the input signal range will not damage the input circuitry as long as the maximum powered-on input voltage rating of ±35 V or powered off voltage rating of ±25 V is not exceeded. The PCI-1200 is guaranteed to withstand inputs up to the maximum input voltage rating.

Chapter 3 Signal Connections

Caution

Exceeding the input signal range distorts input signals. Exceeding the maximum input voltage rating may damage the PCI-1200 board and the computer. National Instruments is

liable for any damages resulting from such signal connections.

NOT

Table 3-2.

Bipolar Analog Input Signal Range Versus Gain

Gain Setting Input Signal Range

1 –5.0 to 4.99756 V

2 –2.5 to 2.49878 V

5 –1.0 to 0.99951 V

10 –500 to 499.756 mV

20 –250 to 249.877 mV

50 –100 to 99.951 mV

100 –50 to 49.975 mV

Table 3-3.

Unipolar Analog Input Signal Range Versus Gain

Gain Setting Input Signal Range

1 0 to 9.99756 V

2 0 to 4.99878 V

Chapter 3 Signal Connections

Table 3-3.

Unipolar Analog Input Signal Range Versus Gain

5 0 to 1.99951 V

10 0 to 999.756 mV

20 0 to 499.877 mV

50 0 to 199.951 mV

20 0 to 99.975 mV

How you connect analog input signals to the PCI-1200 depends on how you configure the PCI-1200 analog input circuitry and the type of input signal source. With different PCI-1200 configurations, you can use the PCI-1200 instrumentation amplifier in different ways. Figure 3-2 shows a diagram of the PCI-1200 instrumentation amplifier.

Instrumentation

–

Amplifier

Measured

Voltage

–

= [V

- V

] * GAIN

Figure 3-2.

PCI-1200 Instrumentation Amplifier

The PCI-1200 instrumentation amplifier applies gain, common-mode voltage rejection, and high-input impedance to the analog input signals connected to the PCI-1200 board. Signals are routed to the positive and negative inputs of the instrumentation amplifier through input multiplexers on the PCI-1200. The instrumentation amplifier converts two input signals to a signal that is the difference between the two input signals multiplied by the gain setting of the amplifier. The amplifier output voltage is referenced to the PCI-1200 ground. The PCI-1200 ADC measures this output voltage when it performs A/D conversions.

All signals must be referenced to ground, either at the source device or at the PCI-1200. If you have a floating source, you must use a ground-referenced input connection at the PCI-1200. If you have a

Chapter 3 Signal Connections

grounded source, you must use a nonreferenced input connection at the PCI-1200.

Types of Signal Sources

When configuring the input mode of the PCI-1200 and making signal connections, first determine whether the signal source is floating or ground referenced. These two types of signals are described as follows.

Floating Signal Sources

A floating signal source is not connected in any way to the building ground system but 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. Tie the ground reference of a floating signal to the PCI-1200 analog input ground to establish a local or onboard reference for the signal. Otherwise, the measured input signal varies or appears to float. An instrument or device that supplies an isolated output falls into the floating signal source category.

Ground-Referenced Signal Sources

A ground-referenced signal source is connected in some way to the building system ground and is, therefore, already connected to a common ground point with respect to the PCI-1200, assuming that the computer is plugged into the same power system. Nonisolated outputs of instruments and devices that plug into the building power system fall into this category.

The difference in ground potential between two instruments connected to the same building power system is typically between 1 and 100 mV but can be much higher if power distribution circuits are not properly connected. The connection instructions that follow for grounded signal sources eliminate this ground potential difference from the measured signal.

Note

If you power both the PCI-1200 and your computer with a floating power source (such as a battery), your system may be floating with respect to earth ground. In this case, treat all of your signal sources as floating sources.

Input Configurations

You can configure the PCI-1200 for one of three input modes—RSE, NRSE, or DIFF. The following sections discuss the use of single-ended and differential measurements, and considerations for measuring both floating

Chapter 3 Signal Connections

and ground-referenced signal sources. Table 3-4 summarizes the recommended input configurations for both types of signal sources.

Table 3-4.

Summary of Analog Input Connections

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

ACH(+)

ACH (-)

AIGND

See text for information on bias resistors.

ACH

AIGND

Grounded Signal Source

Examples

• Plug-in instruments with nonisolated outputs

NOT RECOMMENDED

+ Vg -

ACH(+)

ACH (-)

ACH

AIGND

Ground-loop losses, Vg, are added to measured signal

Single-Ended —

Nonreferenced

(NRSE)

ACH

AISENSE

AIGND

ACH

AISENSE

AIGND

See text for information on bias resistors.

+ 70 hidden pages

National Instruments PCI-1200 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

PCI-1200 User Manual

Important Information

Contents

Figures

Tables

About This Manual

Organization of This Manual

Conventions Used in This Manual

National Instruments Documentation

Related Documentation

Customer Communication

What You Need to Get Started

Unpacking

Software Programming Choices

National Instruments Application Software

Register-Level Programming

Optional Equipment

Custom Cabling

Software Installation

Hardware Installation

Board Configuration

Analog I/O Configuration

Analog Output Polarity

Analog Input Polarity

Analog Input Mode

I/O Connector

Signal Connection Descriptions

Analog Input Signal Connections

Types of Signal Sources

Input Configurations