National Instruments DAQPAD-1200 User Manual

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DAQPadTM-1200

User Manual

Data Acquisition and Control for the Parallel Port

November 1995 Edition

Part Number 371351A-01

National Instruments Corporate Headquarters

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Limited Warranty

The DAQPad-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.

EXCEPT AS SPECIFIED HEREIN, NATIONAL INSTRUMENTS MAKES NO WARRANTIES, EXPRESS OR IMPLIED,

AND SPECIFICALLY DISCLAIMS ANY WARRANTY OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. CUSTOMER’S RIGHT TO RECOVER DAMAGES CAUSED BY FAULT OR NEGLIGENCE ON THE PART OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER.

NATIONAL INSTRUMENTS WILL NOT BE LIABLE FOR DAMAGES RESULTING FROM LOSS OF DATA, PROFITS,

USE OF PRODUCTS, OR INCIDENTAL OR CONSEQUENTIAL DAMAGES, EVEN IF ADVISED OF THE POSSIBILITY THEREOF. This limitation of the liability of 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.

Copyright

Under the copyright laws, this publication may not be reproduced or transmitted in any form, electronic or mechanical, including photocopying, recording, storing in an information retrieval system, or translating, in whole or in part, without the prior written consent of National Instruments Corporation.

Trademarks

LabVIEW®, NI-DAQ

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

, and RTSI

are trademarks of National Instruments Corporation.

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.............................................................................................................ix

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

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

National Instruments Documentation............................................................................x

Related Documentation..................................................................................................xi

Customer Communication.............................................................................................xi

Chapter 1

Introduction..........................................................................................................................1-1

About the DAQPad-1200...............................................................................................1-1

What You Need to Get Started ......................................................................................1-2

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

LabVIEW and LabWindows/CVI Application Software..................................1-2

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

Optional Equipment.......................................................................................................1-4

BP-1 Battery Pack..............................................................................................1-4

Adding an Enhanced Parallel Port (EPP)...........................................................1-4

Custom Cables...................................................................................................1-5

Chapter 2

Installation and Configuration.......................................................................................2-1

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

Configuration.................................................................................................................2-1

Parallel Port Configuration................................................................................2-2

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

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

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

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

RSE Input (Eight Channels, Reset Condition)...........................2-3

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

DIFF Input (Four Channels) ......................................................2-4

Chapter 3

Signal Connections.............................................................................................................3-1

Transparent Parallel Port Connector..............................................................................3-1

Front Connector.............................................................................................................3-1

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

Analog Input Signal Connections......................................................................3-4

Types of Signal Sources.........................................................................3-6

Floating Signal Sources .............................................................3-6

Ground-Referenced Signal Sources...........................................3-6

Input Configurations..............................................................................3-6

Contents

Differential Connection Considerations

(DIFF Configuration).................................................................3-8

Differential Connections for Grounded Signal Sources ............3-8

Differential Connections for Floating Signal Sources...............3-9

Single-Ended Connection Considerations .................................3-10

Single-Ended Connections for Floating Signal Sources

(RSE Configuration)..................................................................3-11

Single-Ended Connections for Grounded Signal Sources

(NRSE Configuration)...............................................................3-12

Common-Mode Signal Rejection Considerations......................3-12

Analog Output Signal Connections....................................................................3-13

Digital I/O Signal Connections..........................................................................3-14

Port C Pin Connections..........................................................................3-16

Timing Specifications............................................................................3-16

Mode 1 Input Timing.................................................................3-17

Mode 1 Output Timing ..............................................................3-18

Mode 2 Bidirectional Timing.....................................................3-19

DAQ and General-Purpose Timing Signal Connections...................................3-19

DAQ Timing Connections.....................................................................3-20

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

Power Connections ............................................................................................3-26

Field Wiring Considerations..........................................................................................3-27

Chapter 4

Calibration.............................................................................................................................4-1

Calibration at Higher Gains...........................................................................................4-2

Calibration Equipment Requirements............................................................................4-2

Using the Calibration Function......................................................................................4-2

Appendix A

Specifications........................................................................................................................A-1

Appendix B

Parallel Port Configuration Troubleshooting...........................................................B-1

Appendix C

Customer Communication...............................................................................................C-1

Glossary......................................................................................................................Glossary-1

Index..................................................................................................................................Index-1

DAQPad-1200 User Manual vi © National Instruments Corporation

Contents

Figures

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

and Your Hardware............................................................................................1-3

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

Figure 3-2. DAQPad-1200 Instrumentation Amplifier.........................................................3-5

Figure 3-3. Summary of Analog Input Connections.............................................................3-7

Figure 3-4. Differential Input Connections for Grounded Signal Sources...........................3-9

Figure 3-5. Differential Input Connections for Floating Sources.........................................3-10

Figure 3-6. Single-Ended Input Connections for Floating Signal Sources...........................3-11

Figure 3-7. Single-Ended Input Connections for Grounded Signal Sources........................3-12

Figure 3-8. Analog Output Signal Connections....................................................................3-14

Figure 3-9. Digital I/O Connections.....................................................................................3-15

Figure 3-10. Mode 1 Timing Specifications for Input Transfers............................................3-17

Figure 3-11. Mode 1 Timing Specifications for Output Transfers.........................................3-18

Figure 3-12. Mode 2 Timing Specification for Bidirectional Transfers.................................3-19

Figure 3-13. EXTCONV* Signal Timing...............................................................................3-20

Figure 3-14. Posttrigger DAQ Timing....................................................................................3-21

Figure 3-15. Pretrigger DAQ Timing.....................................................................................3-21

Figure 3-16. Interval-Scanning Signal Timing.......................................................................3-22

Figure 3-17 EXTUPDATE* Signal Timing for Updating DAC Output...............................3-23

Figure 3-18. Event-Counting Application with External Switch Gating................................3-24

Figure 3-19. Frequency Measurement Application................................................................3-25

Figure 3-20. General-Purpose Timing Signals.......................................................................3-26

Tables

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

Table 2-2. Analog Input Modes for the DAQPad-1200......................................................2-3

Table 3-1. Bipolar Analog Input Signal Range Versus Gain..............................................3-4

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

Table 3-3. Port C Signal Assignments................................................................................3-16

About This Manual

This manual describes the electrical and mechanical aspects of the DAQPad-1200 and contains information concerning its operation and programming. The DAQPad-1200 is an independent data acquisition unit that communicates with the PC through the parallel port.

Organization of This Manual

The DAQPad-1200 User Manual is organized as follows:

• Chapter 1, Introduction, describes the DAQPad-1200; lists what you need to get started with your DAQPad-1200; and describes the software programming choices and optional equipment.

• Chapter 2, Installation and Configuration, describes how to install and software configure the DAQPad-1200.

• Chapter 3, Signal Connections, describes the connection of a standard parallel port device to the rear panel transparent parallel port connector, the signal connections to the DAQPad-1200 unit via the DAQPad-1200 front I/O connector, and includes specifications and connection instructions for the DAQPad-1200 connector signals.

• Chapter 4, Calibration, discusses the calibration procedures for the DAQPad-1200 analog I/O circuitry.

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

• Appendix B, Parallel Port Configuration Troubleshooting, contains installation troubleshooting information.

• Appendix C, 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, 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: bold italic Bold italic text denotes a note, caution, or warning. italic Italic text denotes emphasis, a cross reference, or an introduction to a key

concept. MC MC refers to the Micro Channel series computers. monospace Lowercase text in this font denotes text or characters that are to be literally

input 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, variables, filenames, and extensions, and for statements

and comments taken from program code. NB NB refers to the NuBus series computers. NI-DAQ NI-DAQ is used throughout this manual to refer to the NI-DAQ software

for PC compatibles, unless otherwise noted. PC PC refers to the IBM PC/XT, the IBM PC AT, and compatible computers. Abbreviations, acronyms, metric prefixes, mnemonics, symbols, and terms are listed in the

Glossary.

National Instruments Documentation

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

• 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 manuals—Examples of software manuals you may have are the LabVIEW and

LabWindows® /CVI manual sets and the NI-DAQ manuals. After you set up your hardware system, use either the application software (LabVIEW or LabWindows/CVI) manuals or the NI-DAQ manuals to help you write your application. If you have a large and complicated system, it is worthwhile to look through the software manuals 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 or 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.

DAQPad-1200 User Manual x © National Instruments Corporation

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 C, Customer

Communication, at the end of this manual.

Chapter 1 Introduction

This chapter describes the DAQPad-1200; lists what you need to get started with your DAQPad-1200; and describes the software programming choices and optional equipment.

About the DAQPad-1200

The DAQPad-1200 is a low-cost high-performance DAQ unit that communicates with the PC through the parallel port on IBM PC/XT/AT and compatible computers. The DAQPad-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 DAQPad-1200 is completely software-configurable and self-calibrated. You never need to open the unit to set jumpers or adjust trimpots.

The DAQPad-1200 is register- and pin-compatible with the Lab-PC+ multifunction I/O plug-in board. The DAQPad-1200 is EPP compatible with IEEE 1284, a standard for high-performance PC parallel ports. The DAQPad-1200 works with two different parallel port types–the original Centronics or unidirectional port for printers, and the Enhanced Parallel Port (EPP). The DAQPad-1200 has a second parallel port connector for transparent pass-through connection to a standard parallel port device.

You can power the DAQPad-1200 from the included AC adapter, the optional BP-1 rechargeable DAQPad battery pack, or any 9 to 42 VDC source such as a standard 12 V car battery.

By combining multifunction analog, digital, and timing I/O capabilities in a compact, lightweight unit, the DAQPad-1200 is ideal for portable applications using notebook computers or any PC with a parallel printer port. Because the DAQPad-1200 can take advantage of the high throughput capabilities of the PC parallel port, the unit delivers high-performance data acquisition and control for any application where PC expansion slots are unavailable.

Introduction Chapter 1

What You Need to Get Started

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

DAQPad-1200 unit

DAQPad-1200 User Manual

NI-DAQ software for PC compatibles, with manuals Parallel port cable 120 or 230 VAC wall-mount power supply adapter, the BP-1 battery power supply,

or any 9–42 VDC power supply IBM PC/XT/AT or compatible computer

Detailed specifications of the DAQPad-1200 are listed in Appendix A, Specifications.

Software Programming Choices

There are four options to choose from when programming your National Instruments DAQ and SCXI hardware. You can use LabVIEW, LabWindows/CVI, or NI-DAQ.

The DAQPad-1200 works with LabVIEW for Windows, LabWindows/CVI for Windows, and the NI-DAQ software for PC compatibles.

LabVIEW and LabWindows/CVI Application Software

LabVIEW and LabWindows/CVI are innovative program development software packages for data acquisition and control applications. LabVIEW uses graphical programming, whereas LabWindows/CVI enhances traditional programming languages. Both packages include extensive libraries for data acquisition, instrument control, data analysis, and graphical data presentation.

LabVIEW features interactive graphics, a state-of-the-art user interface, and a powerful graphical programming language. The LabVIEW Data Acquisition VI Library, a series of VIs for using LabVIEW with National Instruments DAQ hardware, is included with LabVIEW. The LabVIEW Data Acquisition VI Libraries are 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 libraries are functionally equivalent to the NI-DAQ software.

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

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

Chapter 1 Introduction

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 extended memory.

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—up to 500 kS/s on ISA computers and up to 1 MS/s on EISA computers.

NI-DAQ also internally addresses many of the complex issues between the computer and the DAQ hardware such as programming the PC interrupt and DMA controllers. NI-DAQ maintains a consistent software interface among its different versions so that you can change platforms with minimal modifications to your code. Figure 1-1 illustrates the relationship between NIDAQ and LabVIEW and LabWindows/CVI. You can see that the DAQ parts of LabVIEW and LabWindows/CVI are functionally equivalent to the NI-DAQ software.

Conventional

Programming

Environment

(PC, Macintosh, or

Sun SPARCstation)

DAQ or

SCXI Hardware

LabVIEW

(PC, Macintosh, or

Sun SPARCstation)

NI-DAQ

Driver Software

LabWindows/CVI

(PC or Sun

SPARCstation)

Personal

Computer or

Workstation

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

NI-DAQ, and Your Hardware

Introduction Chapter 1

Register-Level Programming

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

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

Optional Equipment

Contact National Instruments to order any of the following optional equipment:

BP-1 battery pack with a 110 or 230 VAC charger

0.5 or 1.0 m type NB1 ribbon cable CB-50 I/O connector block with a 1.0 m type NB1 cable CB-50 I/O connector block only SC-2071 general-purpose termination breadboard with a 0.5 or 1.0 m type NB1 ribbon cable 2 m parallel port cable

BP-1 Battery Pack

For total portability, you can power the DAQPad-1200 with the optional BP-1 battery pack. The BP-1 includes a 12 V, 3.2 Ahr battery packaged in an enclosure with the same dimensions as the DAQPad-1200. A fully charged BP-1 typically powers the DAQPad-1200 for 11 hours. A charger unit is included with the BP-1.

Adding an Enhanced Parallel Port (EPP)

If you have a slot available in your PC, you can add an EPP card to achieve higher DAQ rates. You can order one such card, the F/Port Enhanced Parallel Port Card, from Far Point Communications. You can use the card in a PC/AT 386, 486, or compatible computer.

If you have a PCMCIA type II slot available in your PC, you can add a PCMCIA to an EPP card to achieve higher DAQ rates. Two options are the SPP-100 from Quatech and the ExpressPort from FarPoint. Both cards comply with the PCMCIA PC Standard Specification 2.1.

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

Chapter 1 Introduction

Custom Cables

The DAQPad-1200 front signal connector is a 50-pin male ribbon-cable header. The manufacturer part number of the header National Instruments uses is as follows:

• AMP Inc. (part number 1-103310-0) The mating connector for the DAQPad-1200 front signal connector is a 50-position polarized

ribbon-socket connector with strain relief. National Instruments uses a polarized or keyed connector to prevent inadvertent upside-down connection to the DAQPad-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) Standard 50-conductor 28 AWG stranded ribbon cables that work with these connectors are as

follows:

• Electronic Products Division/3M (part number 3365/50)

• T&B/Ansley Corporation (part number 171-50) The DAQPad-1200 two rear connectors (the parallel and transparent parallel port connectors) are

the standard 25-pin D-Subminiature. The manufacturer part number of the connector National Instruments uses is as follows:

• AMP Inc. (part number 747846-5) You can use standard DB-25-style male connectors as mating connectors for the DAQPad-1200

rear connector.

Chapter 2 Installation and Configuration

This chapter describes how to install and software configure the DAQPad-1200.

Hardware Installation

There are five basic steps to installing the DAQPad-1200:

Note: If you are using the BP-1 battery pack, follow the installation instructions in your

BP-1 installation guide instead of steps 1 and 2. The maximum recommended discharge time for a fully-charged battery pack is 11 hours for an unloaded DAQPad-1200 and five hours for a DAQPad-1200 loaded at 350 mA from the +5 V I/O connector (pin 49).

1. Verify that the voltage on the wall-mount supply matches the voltage supplied in your area.

2. Connect one end of the wall-mount supply to an electrical outlet. Connect the other end to

the rear panel jack.

3. Connect the parallel port cable to the PC parallel port. Connect the other end of the cable to

port A on the DAQPad-1200, and screw in the mounting screws on the connectors to establish a firm connection.

4. If you are using the transparent parallel port, connect another parallel port cable to port B on

the DAQPad-1200. Connect the other end of the second parallel port cable to any standard parallel port device.

5. Push the front panel rocker switch to power on the DAQPad-1200. The power LED should

light up immediately.

If the power LED does not light up immediately, check the polarity of your power connections. The power input of the DAQPad-1200 is protected by a positive temperature coefficient (PTC) resistor. It takes approximately 20 s for the PTC resistor to reset after being tripped. Contact National Instruments if the power LED does not light up after correcting any faulty power connections.

The DAQPad-1200 unit is installed. You are now ready to install and configure your software.

Configuration

The DAQPad-1200 is completely software configurable; refer to your software manuals to install and configure the software.

If you are using NI-DAQ, refer to the NI-DAQ User Manual for PC Compatibles. The software installation and configuration instructions are in Chapter 1, Introduction to NI-DAQ. Find the installation and system configuration section for your operating system and follow the instructions given there.

Installation and Configuration Chapter 2

Parallel Port Configuration

During configuration, you must know the parallel port I/O address and interrupt channel. Common parallel port addresses are 0x378, 0x278, 0x3BC, 0x280, and 0x290. The DAQPad-1200 can use the parallel port hardware interrupts for interrupt-driven data acquisition. Interrupt levels 7 and 5 are commonly used for parallel ports. Refer to your parallel port reference manual for details about interrupt selection and address assignment. If you have problems configuring your parallel port, refer to Appendix B, Parallel Port Configuration Troubleshooting.

Analog I/O Configuration

On power up or after a software reset, the DAQPad-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 DAQPad-1200 and shows the

configuration in reset condition.

Table 2-1. Analog I/O Settings

Parameter Configuration

Analog Output CH0 Polarity Bipolar–±5 V (reset condition); Unipolar–0 to 10 V Analog Output CH1 Polarity Bipolar–±5 V (reset condition); Unipolar–0 to 10 V Analog Input Polarity Bipolar–±5 V (reset condition); Unipolar–0 to 10 V Analog Input Mode Referenced single-ended (RSE) (reset condition)

Nonreferenced single-ended (NRSE) Differential (DIFF)

Both the analog input and analog output circuitries are software configurable.

Analog Output Polarity

The DAQPad-1200 has two channels of analog output voltage at the front panel 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 V to +5 V at the analog output. In addition, you can select the coding scheme for each 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).

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

Chapter 2 Installation and Configuration

Analog Input Polarity

You can select the analog input on the DAQPad-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 DAQPad-1200 has three different input modes–referenced single-ended (RSE) input, nonreferenced single-ended (NRSE) input, and differential (DIFF) input. The single-ended input configurations use eight channels. The DIFF input configuration uses four channels. Table 2-2 describes these configurations.

Table 2-2. Analog Input Modes for the DAQPad-1200

Analog Input

Description

Modes

RSE Referenced single-ended mode provides eight single-ended inputs with the

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

NRSE Nonreferenced single-ended mode provides eight single-ended inputs with the

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

DIFF Differential 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, 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 DAQPad-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 DAQPad-1200 can monitor eight different analog input channels.

Installation and Configuration Chapter 2

Considerations for using the RSE configuration are discussed in Chapter 3, Signal Connections. Notice that in this mode, the return path of the signal 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 DAQPad-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.

Considerations for using the NRSE configuration are discussed in Chapter 3, Signal Connections. Notice that in this mode, the return path of the signal 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 DAQPad-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 negative terminal of the amplifier and through channel 1, 3, 5, or 7, depending on which channel pair you select.

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

Chapter 3 Signal Connections

This chapter describes the connection of a standard parallel port device to the rear panel transparent parallel port connector, the signal connections to the DAQPad-1200 unit via the DAQPad-1200 front I/O connector, and includes specifications and connection instructions for the DAQPad-1200 connector signals.

Transparent Parallel Port Connector

Note: You must power on the DAQPad-1200 to operate the standard parallel port device

which is connected to the transparent parallel port connector.

The DAQPad-1200 supports transparent parallel port connection to any standard parallel port device. The DAQPad-1200 does not support transparent parallel port connection to any device which supports the 1284 daisy-chain specification as defined by DISTEC, Inc.

When you power up the DAQPad-1200, the unit is in transparent mode. If you are using NI-DAQ, the DAQPad-1200 will be placed into transparent mode at the completion of every operation. In this mode, the DAQPad-1200 will transparently pass through all of the parallel port lines with minimal propagation delay. In normal applications, you operate either the DAQPad-1200 or the standard parallel port device connected to the transparent parallel port connector at any one time. For example, you cannot use a printer connected to the transparent parallel port connector and perform a DAQ operation at the same time. You can use the printer only after the DAQ operation has finished.

Front Connector

Figure 3-1 shows the pin assignments for the DAQPad-1200 front I/O connector. This connector is located on the front panel of the DAQPad-1200 unit.

Warning: Connections that exceed any of the maximum ratings of input or output signals

on the DAQPad-1200 may result in damage to the DAQPad-1200 unit and to the PC. This includes connecting any power signals to ground and vice versa. National Instruments is signal connections.

NOT liable for any damages resulting from any such

Signal Connections Chapter 3

ACH0 ACH2 ACH4 ACH6

AISENSE/AIGND

PC3

12 34 56 78

9 10

11 12 13 14 15 16 17 18 19 20

21 22 23 24

26 27 28 29 30 31 32 33 34

ACH1 ACH3 ACH5 ACH7 DAC0OUT

DAC1OUTAGND PA0DGND PA2PA1 PA4PA3 PA6PA5 PB0PA7 PB2PB1 PB4PB3 PB6PB5 PC0PB7 PC2PC1 PC4

35 36

PC5 PC6

37 38

PC7 EXTTRIG

EXTUPDATE*

OUTB0

CLKB1

+5 V

39 40 41 42 43 44 45 46 47 48 49 50

EXTCONV* GATB0 GATB1OUTB1 OUTB2 CLKB2GATB2 DGND

Figure 3-1. DAQPad-1200 Front I/O Connector Pin Assignments

DAQPad-1200 User Manual 3-2 © National Instruments Corporation

Chapter 3 Signal Connections

Signal Connection Descriptions

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

Signal Name Direction Reference Description

ACH<0..7> AI AGND Analog Channel 0 through 7—Analog input channels 0 through 7. AISENSE/AIGND I/O AGND Analog Input Sense/Analog Input Ground—Connected to AGND in

DAC0OUT AO AGND Digital-to-Analog Converter 0 Output—Voltage output signal for

AGND N/A N/A Analog Ground—Analog output ground reference for analog output

DAC1OUT AO AGND Digital-to-Analog Converter 1 Output—Voltage output signal for

DGND N/A N/A Digital Ground—Voltage ground reference for the digital signals and

PA<0..7> DI/O DGND Port A 0 through 7—Bidirectional data lines for port A. PA7 is the

PB<0..7> DI/O DGND Port B 0 through 7—Bidirectional data lines for port B. PB7 is the

PC<0..7> DI/O DGND Port C 0 through 7—Bidirectional data lines for port C. PC7 is the

EXTTRIG DI DGND External Trigger—External control signal to trigger a DAQ

EXTUPDATE* DI DGND External Update—External control signal to update DAC outputs. EXTCONV* DI DGND External Convert—External control signal to time A/D conversions. OUTB0 DO DGND Output B0—Voltage output signal of counter B0. GATB0 DI DGND Gate B0—External control signal for gating counter B0. OUTB1 DI/O DGND OutputB1—Voltage output signal of counter B1 when selected as

GATB1 DI DGND Gate B1—External control signal for gating counter B1. CLKB1 DI DGND Clock B1—External control clock signal for counter B1.

RSE mode, analog input sense in NRSE mode.

analog output channel 0.

voltages. Bias current return point for differential measurements.

analog output channel 1.

the +5 V supply.

MSB, and PA0 is the LSB.

MSB, and PB0 is the LSB.

MSB, and PC0 is the LSB.

operation.

output. External control signal for timing an interval cycle when selected as input.

OUTB2 DO DGND Counter B2—Voltage output signal of counter B2. GATB2 DI DGND Gate B2—External control signal for gating counter B2. CLKB2 DI DGND Clock B2—External control clock signal for counter B2. +5 V DO DGND +5 Volts—This pin is fused for up to 400 mA of +5 V supply. DGND N/A N/A Digital Ground—Voltage ground reference for the digital signals and

*Indicates that the signal is active low.

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

the +5 V supply.

Signal Connections Chapter 3

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. Signal connection guidelines for each of these groups are described in the following sections.

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 DAQPad-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 singleended analog input channels of the input multiplexer through 4.7 kΩ series resistances. Pins 2, 4, 6, and 8 are also tied to an input multiplexer for DIFF mode.

The signal ranges for inputs ACH<0..7> at all possible gains are shown in Table 3-1 and Table 3-2. Exceeding the input signal range will not damage the input circuitry as long as the maximum input voltage rating of ±42 V is not exceeded. The DAQPad-1200 is guaranteed to withstand inputs up to the maximum input voltage rating.

Warning: Exceeding the input signal range results in distorted input signals. Exceeding the

maximum input voltage rating may cause damage to the DAQPad-1200 unit and to the computer. National Instruments is from such signal connections.

NOT liable for any damages resulting

Table 3-1. 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

DAQPad-1200 User Manual 3-4 © National Instruments Corporation

Chapter 3 Signal Connections

Table 3-2. Unipolar Analog Input Signal Range Versus Gain

Gain Setting Input Signal Range

1 0 to 9.99756 V 2 0 to 4.99878 V 5 0 to 1.99951 V 10 0 to 999.756 mV 20 0 to 499.877 mV 50 0 to 199.951 mV 100 0 to 99.975 mV

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

Instrumentation

Amplifier

Measured

Voltage

= [V

- V

] * GAIN

Figure 3-2. DAQPad-1200 Instrumentation Amplifier

The DAQPad-1200 instrumentation amplifier applies gain, common-mode voltage rejection, and high-input impedance to the analog input signals connected to the DAQPad-1200 unit. Signals are routed to the positive and negative inputs of the instrumentation amplifier through input multiplexers on the DAQPad-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 DAQPad-1200 ground. The DAQPad-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 DAQPad-1200. If you have a floating source, you must use a ground-referenced input connection at the DAQPad-1200. If you have a grounded source, you must use a nonreferenced input connection at the DAQPad-1200.

Signal Connections Chapter 3

Types of Signal Sources

When configuring the input mode of the DAQPad-1200 and making signal connections, you must 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. You must tie the ground reference of a floating signal to the DAQPad-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 DAQPad-1200, assuming that the PC 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 mV 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 DAQPad-1200 and your PC with a floating power source (such

as a battery), then 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 DAQPad-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 and ground-referenced signal sources. Figure 3-3 summarizes the recommended input configurations for both types of signal sources.

DAQPad-1200 User Manual 3-6 © National Instruments Corporation

Chapter 3 Signal 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.

Figure 3-3. Summary of Analog Input Connections

Signal Connections Chapter 3

Differential Connection Considerations (DIFF Configuration) Differential connections are those in which each DAQPad-1200 analog input signal has its own

reference signal or signal return path. These connections are available when you configure the DAQPad-1200 in the DIFF mode. Each input signal is tied to the positive input of the instrumentation amplifier, and its reference signal, or return, is tied to the negative input of the instrumentation amplifier.

When you configure the DAQPad-1200 for DIFF input, each signal uses two of the multiplexer inputs—one for the signal and one for its reference signal. Therefore, only four analog input channels are available when using the DIFF configuration. You should use the DIFF input configuration when any of the following conditions are present:

• Input signals are low level (less than 1 V).

• Leads connecting the signals to the DAQPad-1200 are greater than 15 ft.

• Any of the input signals requires a separate ground-reference point or return signal.

• The signal leads travel through noisy environments. Differential signal connections reduce picked-up noise and increase common-mode signal and

noise rejection. With these connections, input signals can float within the common-mode limits of the input instrumentation amplifier.

Differential Connections for Grounded Signal Sources Figure 3-4 shows how to connect a ground-referenced signal source to a DAQPad-1200 unit

configured for DIFF input. Configuration instructions are included in the Analog I/O

Configuration section in Chapter 2, Installation and Configuration.

DAQPad-1200 User Manual 3-8 © National Instruments Corporation

Chapter 3 Signal Connections

ACH 0

ACH 2

ACH 4

ACH 6

Grounded Signal Source

Measured Voltage

CommonMode Noise, Ground Potential, and so on

Front I/O Connector

ACH 1

ACH 3

ACH 5

ACH 7

AGND

DAQPad-1200 Unit in DIFF Configuration

Figure 3-4. Differential Input Connections for Grounded Signal Sources

With this type of connection, the instrumentation amplifier rejects both the common-mode noise in the signal and the ground-potential difference between the signal source and the DAQPad-1200 ground (shown as V

in Figure 3-4).

Differential Connections for Floating Signal Sources Figure 3-5 shows how to connect a floating signal source to a DAQPad-1200 unit that is

configured for DIFF input. Configuration instructions are included in the Analog I/O

Configuration section of Chapter 2, Installation and Configuration.

Signal Connections Chapter 3

ACH 0

ACH 2

ACH 4

Floating Signal Source

ACH 6

Measured Voltage

100 kΩ

Bias Current Return Paths

Front I/O Connector

100 kΩ

2 4

ACH 1 ACH 3 ACH 5

ACH 7

AGND

DAQPad-1200 Unit in DIFF Configuration

Figure 3-5. Differential Input Connections for Floating Sources

The 100 kΩ resistors shown in Figure 3-5 create a return path to ground for the bias currents of the instrumentation amplifier. If there is no return path, the instrumentation amplifier bias currents charge stray capacitances, resulting in uncontrollable drift and possible saturation in the amplifier. Typically, values from 10 to 100 kΩ are used.

A resistor from each input to ground, as shown in Figure 3-5, provides bias current return paths for an AC-coupled input signal.

If the input signal is DC-coupled, you need only the resistor that connects the negative signal input to ground. This connection does not lower the input impedance of the analog input channel.

Single-Ended Connection Considerations Single-ended connections are those in which all DAQPad-1200 analog input signals are

referenced to one common ground. The input signals are tied to the positive input of the instrumentation amplifier, and their common ground point is tied to the negative input of the instrumentation amplifier.

DAQPad-1200 User Manual 3-10 © National Instruments Corporation

Chapter 3 Signal Connections

When the DAQPad-1200 is configured for single-ended input (NRSE or RSE), eight analog input channels are available. You can use single-ended input connections when the following criteria are met by all input signals:

1. Input signals are high level (greater than 1 V).

2. Leads connecting the signals to the DAQPad-1200 are less than 15 ft.

3. All input signals share a common reference signal (at the source). If any of the preceding criteria are not met, using DIFF input configuration is recommended. You can software configure the DAQPad-1200 for two different types of single-ended

connections, RSE configuration and NRSE configuration. Use the RSE configuration for floating signal sources; in this case, the DAQPad-1200 provides the reference ground point for the external signal. Use the NRSE configuration for ground-referenced signal sources; in this case, the external signal supplies its own reference ground point and the DAQPad-1200 should not supply one.

Single-Ended Connections for Floating Signal Sources (RSE Configuration) Figure 3-6 shows how to connect a floating signal source to a DAQPad-1200 unit configured for

single-ended input. You must configure the DAQPad-1200 analog input circuitry for RSE input to make these types of connections. Configuration instructions are included in the Analog I/O Configuration section of Chapter 2, Installation and Configuration.

ACH 0

ACH 1

ACH 2

Floating

Signal

Source

Front I/O Connector

ACH 7

AISENSE/AIGND

AGND

DAQPad-1200 Unit in RSE Configuration

Measured Voltage

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

Signal Connections Chapter 3

Single-Ended Connections for Grounded Signal Sources (NRSE Configuration) If you measure a grounded signal source with a single-ended configuration, you must configure

the DAQPad-1200 in the NRSE input configuration. The signal is connected to the positive input of the DAQPad-1200 instrumentation amplifier and the signal local ground reference is connected to the negative input of the DAQPad-1200 instrumentation amplifier. Therefore, you must connect the ground point of the signal to the AISENSE pin. Any potential difference between the DAQPad-1200 ground and the signal ground appears as a common-mode signal at both the positive and negative inputs of the instrumentation amplifier and is therefore rejected by the amplifier. On the other hand, if the input circuitry of the DAQPad-1200 is referenced to ground, such as in the RSE configuration, this difference in ground potentials appears as an error in the measured voltage.

Figure 3-7 shows how to connect a grounded signal source to a DAQPad-1200 unit configured in the NRSE configuration. Configuration instructions are included in the Analog I/O Configuration section in Chapter 2, Installation and Configuration.

ACH 0 ACH 1

ACH 2

Ground-

Referenced

Signal

Source

Common-

Mode Noise

and so on

Front I/O Connector

ACH 7

AISENSE/AIGND

AGND

DAQPad-1200 Unit in NRSE Input Configuration

Measured Voltage

Figure 3-7. Single-Ended Input Connections for Grounded Signal Sources Common-Mode Signal Rejection Considerations Figures 3-4 and 3-7 show connections for signal sources that are already referenced to some

ground point with respect to the DAQPad-1200. In these cases, the instrumentation amplifier can reject any voltage caused by ground-potential differences between the signal source and the DAQPad-1200. In addition, with differential input connections, the instrumentation amplifier can reject common-mode noise pickup in the leads connecting the signal sources to the DAQPad-1200.

DAQPad-1200 User Manual 3-12 © National Instruments Corporation

Chapter 3 Signal Connections

The common-mode input range of the DAQPad-1200 instrumentation amplifier is the magnitude of the greatest common-mode signal that can be rejected.

The common-mode input range for the DAQPad-1200 depends on the size of the differential input signal (V

diff

= V

- V

)and the gain setting of the instrumentation amplifier. In unipolar

mode, the differential input range is 0 to 10 V. In bipolar mode, the differential input range is

-5 to +5 V. Inputs should remain within a range of -5 to 10 V in both bipolar and unipolar modes.

Analog Output Signal Connections

Pins 10 through 12 of the front connector are analog output signal pins. Pins 10 and 12 are the DAC0OUT and DAC1OUT signal pins. DAC0OUT is the voltage output

signal for analog output channel 0. DAC1OUT is the voltage output signal for analog output channel 1.

Pin 11, AGND, is the ground-reference point for both analog output channels as well as analog input.

The following output ranges are available:

• Output signal range

– Bipolar output ±5 V

– Unipolar output 0 to 10 V

Maximum load current ±2 mA for 12-bit linearity.

Figure 3-8 shows how to make analog output signal connections.

Signal Connections Chapter 3

Load

Front I/O Connector

VOUT 0

VOUT 1

Figure 3-8. Analog Output Signal Connections

Digital I/O Signal Connections

10 DAC0OUT

AGND

DAC1OUT

Channel 0

Channel 1

Analog Output Channels

DAQPad-1200 Unit

Pins 13 through 37 of the front connector are digital I/O signal pins. Digital I/O on the DAQPad-1200 uses the 82C55A integrated circuit. The 82C55A is a general-purpose peripheral interface containing 24 programmable I/O pins. These pins represent the three 8-bit ports (PA, PB, and PC) of the 82C55A.

Pins 14 through 21 are connected to the digital lines PA<0..7> for digital I/O port A. Pins 22 through 29 are connected to the digital lines PB<0..7> for digital I/O port B. Pins 30 through 37 are connected to the digital lines PC<0..7> for digital I/O port C. Pin 13, DGND, is the digital ground pin for all three digital I/O ports. Refer to Appendix A, Specifications, for signal voltage and current specifications.

DAQPad-1200 User Manual 3-14 © National Instruments Corporation

Chapter 3 Signal Connections

Figure 3-9 illustrates signal connections for three typical digital I/O applications.

+5 V

LED

+5 V

TTL Signal

Switch

Front I/O Connector

14 PA0

Port A

P A<7..0>

Port B

22 PB0

PB<7..0>

30 PC0

Port C

PC<7..0>

DGND

DAQPad-1200 Unit

Figure 3-9. Digital I/O Connections

In Figure 3-9, port A is configured for digital output, and ports B and C are configured for digital input. Digital input applications include receiving TTL signals and sensing external device states such as the switch in Figure 3-9. Digital output applications include sending TTL signals and driving external devices such as the LED shown in Figure 3-9.

Signal Connections Chapter 3

Port C Pin Connections

The signals assigned to port C depend on the mode in which the 82C55A is programmed. In mode 0, port C is considered to be two 4-bit I/O ports. In modes 1 and 2, port C is used for status and handshaking signals with two or three I/O bits mixed in. Table 3-3 summarizes the signal assignments of port C for each programmable mode. See your DAQPad-1200 Register- Level Programmer Manual for programming information.

Table 3-3. Port C Signal Assignments

Programmable Mode Group A Group B

PC7 PC6 PC5 PC4 PC3 PC2 PC1 PC0

Mode 0 Mode 1 Input

Mode 1 Output

Mode 2

*Indicates that the signal is active low.

I/O I/O I/O I/O I/O I/O I/O I/O

I/O I/O IBF

OBFA* ACKA* I/O I/O INTR

OBFA* ACKA* IBF

STBA* INTR

STBB* IBFB

ACKB* OBFB* INTR

I/O I/O I/O

INTR

Timing Specifications

Use the handshaking lines STB* and IBF to synchronize input transfers. Use the handshaking lines OBF* and ACK* to synchronize output transfers.

The following signals are used in the timing diagrams shown later in this chapter:

Name Type Description

STB* Input Strobe Input—A low signal on this handshaking line loads data into the input latch. IBF Output Input Buffer Full—A high signal on this handshaking line indicates that data has

been loaded into the input latch. This is primarily an input acknowledge signal.

ACK* Input Acknowledge Input—A low signal on this handshaking line indicates that the data

written from the specified port has been accepted. This signal is primarily a response from the external device that it has received the data from the DAQPad-1200.

OBF* Output Output Buffer Full—A low signal on this handshaking line indicates that data has

been written from the specified port.

INTR Output Interrupt Request—This signal becomes high when the 82C55A is requesting

service during a data transfer. Set the appropriate interrupt enable signals to generate this signal.

RD* Internal Read Signal—This signal is the read signal generated from the parallel port interface

circuitry.

WRT* Internal Write Signal—This signal is the write signal generated from the parallel port

interface circuitry.

DATA Bidirectional Data Lines at the Specified Port—This signal indicates when the data on the data

lines at a specified port is or should be available.

DAQPad-1200 User Manual 3-16 © National Instruments Corporation

Chapter 3 Signal Connections

Mode 1 Input Timing The timing specifications for an input transfer in mode 1 are as follows:

T2 T4

STB *

IBF

INTR

RD *

T3 T5

DATA

Name Description Minimum Maximum

T1 STB* pulse width 500 – T2 STB* = 0 to IBF = 1 – 300 T3 Data before STB*= 1 0 – T4 STB* = 1 to INTR = 1 – 300 T5 Data after STB* = 1 180 – T6 RD* = 0 to INTR = 0 – 400 T7 RD* = 1 to IBF = 0 – 300

All timing values are in nanoseconds.

Figure 3-10. Mode 1 Timing Specifications for Input Transfers

Signal Connections Chapter 3

Mode 1 Output Timing The timing specifications for an output transfer in mode 1 are as follows:

WRT*

OBF*

INTR

ACK*

DATA

Name Description Minimum Maximum

T1 WRT* = 0 to INTR = 0 – 450 T2 WRT* = 1 to output – 350 T3 WRT* = 1 to OBF* = 0 – 650 T4 ACK* = 0 to OBF* = 1 – 350 T5 ACK* pulse width 300 – T6 ACK* = 1 to INTR = 1 – 350

All timing values are in nanoseconds.

Figure 3-11. Mode 1 Timing Specifications for Output Transfers

DAQPad-1200 User Manual 3-18 © National Instruments Corporation

Chapter 3 Signal Connections

Mode 2 Bidirectional Timing The timing specifications for bidirectional transfers in mode 2 are as follows:

WRT *

OBF *

INTR

ACK *

STB *

IBF RD *

DATA

T2 T5 T8 T9

Name Description Minimum Maximum

T1 WRT* = 1 to OBF* = 0 – 650 T2 Data before STB*= 1 0 – T3 STB* pulse width 500 – T4 STB* = 0 to IBF = 1 – 300 T5 Data after STB* = 1 180 – T6 ACK* = 0 to OBF = 1 – 350 T7 ACK* pulse width 300 – T8 ACK* = 0 to output – 300 T9 ACK* = 1 to output float 20 250

T10 RD* = 1 to IBF = 0 – 300

T10

All timing values are in nanoseconds.

Figure 3-12. Mode 2 Timing Specification for Bidirectional Transfers

DAQ and General-Purpose Timing Signal Connections

Pins 38 through 48 of the front connector are connections for timing I/O signals. The DAQPad-1200 timing I/O uses two 82C53 counter/timer integrated circuits. One circuit, designated 82C53(A), is used exclusively for DAQ timing, and the other, 82C53(B), is available for general use. You can use pins 38 through 40 and pin 43 to carry external signals for DAQ timing in place of the dedicated 82C53(A). These signals are explained in the next section, DAQ Timing Connections. Pins 41 through 48 carry general-purpose timing signals from 82C53(B). These signals are explained in the General-Purpose Timing Signal Connections section later in this chapter.

Signal Connections Chapter 3

DAQ Timing Connections

Each 82C53 counter/timer circuit contains three counters. Counter 0 on the 82C53(A) counter/timer (referred to as A0) is a sample-interval counter in timed A/D conversions. Counter 1 on the 82C53(A) counter/timer (referred to as A1) is a sample counter in controlled A/D conversions. Therefore, counter A1 stops data acquisition after a predefined number of samples. These counters are not available for general use.

Instead of counter A0, you can use EXTCONV* to externally time conversions. Figure 3-13 shows the timing requirements for the EXTCONV* input. An A/D conversion is initiated by a falling edge on the EXTCONV*.

tw 250 ns minimum

EXTCONV*

A/D Conversion starts within 125 ns from this point.

Figure 3-13. EXTCONV* Signal Timing

The external control signal EXTTRIG can either start a DAQ sequence or terminate an ongoing DAQ sequence depending on the mode—Posttrigger (POSTTRIG) or Pretrigger (PRETRIG). These modes are software selectable.

In the POSTTRIG mode, EXTTRIG serves as an external trigger that initiates a DAQ sequence. When you use counter A0 to time sample intervals, a rising edge on EXTTRIG starts counter A0 and the DAQ sequence. When you use EXTCONV* to time sample intervals, data acquisition is enabled on a rising edge of EXTTRIG followed by a rising edge on EXTCONV*. The first conversion occurs on the next falling edge of EXTCONV*. Further transitions on the EXTTRIG line have no effect until a new DAQ sequence is established.

Figure 3-14 shows a possible controlled DAQ sequence using EXTCONV* and EXTTRIG. The rising edge of EXTCONV* that enables external conversions must occur a minimum of 50 ns after the rising edge of EXTTRIG. The first conversion occurs on the next falling edge of EXTCONV*.

DAQPad-1200 User Manual 3-20 © National Instruments Corporation

Chapter 3 Signal Connections

EXTTRIG

EXTCONV*

CONVERT

tw 50 ns minimum td 50 ns minimum

Figure 3-14. Posttrigger DAQ Timing

In the PRETRIG mode, EXTTRIG serves as a stop-trigger signal. Data is acquired both before and after the stop trigger occurs. A/D conversions are software enabled, which initiates the DAQ operation. However, the sample counter is not started until a rising edge is sensed on the EXTTRIG input. Conversions remain enabled until the sample counter counts to zero. The maximum number of samples acquired after the stop trigger is limited to 65,535. The number of samples acquired before the trigger is limited only by the size of the memory buffer available for data acquisition.

Figure 3-15 shows a pretrigger DAQ timing sequence using EXTTRIG and EXTCONV*. The DAQ operation has been initiated through software. Notice that the sample counter has been programmed to allow five conversions after the rising edge on the EXTTRIG signal. Additional transitions on the EXTTRIG line have no effect until you initiate a new DAQ sequence.

EXTTRIG

EXTCONV*

CONVERT

tw 50 ns minimum

Figure 3-15. Pretrigger DAQ Timing

Signal Connections Chapter 3

Because both pretrigger and posttrigger modes use EXTTRIG input, you can only use one mode at a time.

For interval scanning data acquisition, counter B1 determines the scan interval. Instead of using counter B1, you can externally time the scan interval through OUTB1. If you externally time the sample interval, we recommend that you also externally time the scan interval.

Figure 3-16 shows an example of a multiple-channel interval-scanning DAQ operation. The scan interval and the sample interval are being timed externally through OUTB1 and EXTCONV*. Channels 1 and 0 of the input multiplexers are being scanned once during each scan interval. The first rising edge of EXTCONV* must occur a minimum of 50 ns after the rising edge on OUTB1. The first rising edge of EXTCONV* after the rising edge of OUTB1 enables an internal GATE signal that allows conversions to occur. The first conversion then occurs on the following falling edge of EXTCONV*.

OUTB1

tw = 50 ns

td = 50 ns

EXTCONV*

CONVERT

GATE

ADC CH

CH1 CH0

CH1

CH0

Figure 3-16. Interval-Scanning Signal Timing

You use the final external control signal, EXTUPDATE*, to externally control updating the output voltage of the 12-bit DACs and/or to generate an externally timed interrupt. There are two update modes, immediate update and delayed update. In immediate update mode the analog output is updated as soon as a value is written to the DAC. If you select the delayed update mode, a value is written to the DAC; however, the corresponding DAC voltage is not updated until a low level on the EXTUPDATE* signal is sensed. Furthermore, if you enable interrupt generation, an interrupt is generated whenever a rising edge is detected on the EXTUPDATE* bit. Therefore, you can perform externally timed interrupt-driven waveform generation on the DAQPad-1200.

Figure 3-17 illustrates a waveform generation timing sequence using the EXTUPDATE* signal and the delayed update mode. The DACs are updated by a high level on the DAC OUTPUT UPDATE signal, which in this case is triggered by a low level on the EXTUPDATE* line. CNTINT is the signal that interrupts the PC. This interrupt is generated on the rising edge of EXTUPDATE*. DACWRT is the signal that writes a new value to the DAC.

DAQPad-1200 User Manual 3-22 © National Instruments Corporation

Chapter 3 Signal Connections

EXTUPDATE*

DAC OUTPUT UPDATE

CNTINT

DACWRT

tw Minimum 50 ns

Figure 3-17. EXTUPDATE* Signal Timing for Updating DAC Output

The following rating applies to the EXTCONV*, EXTTRIG, OUTB1, and EXTUPDATE* signals.

• Absolute maximum voltage input rating -0.5 to 7.0 V with respect to DGND For more information concerning the various modes of data acquisition and analog output, refer

to your NI-DAQ manual or to Chapter 2, Theory of Operation, in the DAQPad-1200 Register- Level Programmer Manual.

General-Purpose Timing Signal Connections

The general-purpose timing signals include the GATE, CLK, and OUT signals for the three 82C53(B) counters. The 82C53 counter/timers can be used for general-purpose applications such as pulse and square wave generation; event counting; and pulse-width, time-lapse, and frequency measurement. For these applications, the CLK and GATE signals at the front I/O connector control the counters. The single exception is counter B0, which has an internal 2 MHz clock. Refer to the DAQPad-1200 Register-Level Programmer Manual for programming information.

You perform pulse and square wave generation by programming a counter to generate a timing signal at its OUT output pin. You perform event counting by programming a counter to count rising or falling edges applied to any of the 82C53 CLK inputs. You can then read the counter value to determine the number of edges that have occurred. You can gate counter operations on and off during event counting. Figure 3-18 shows connections for a typical event-counting operation in which a switch is used to gate the counter on and off.

Signal Connections Chapter 3

+5 V

10 kΩ

CLK

OUT

GATE

Signal

Source

Switch

Counter (from Group B)

I/O Connector

DGND

DAQPad-1200 Unit

Figure 3-18. Event-Counting Application with External Switch Gating

Pulse-width measurement is performed by level gating. The pulse you want to measure is applied to the counter GATE input. The counter is loaded with the known count and is programmed to count down while the signal at the GATE input is high. The pulse width equals the counter difference (loaded value minus read value) multiplied by the CLK period.

Perform time-lapse measurement by programming a counter to be edge gated. An edge is applied to the counter GATE input to start the counter. You can program the counter to start counting after receiving a low-to-high edge. The time lapse since receiving the edge equals the counter value difference (loaded value minus read value) multiplied by the CLK period.

To perform frequency measurement, program a counter to be level gated and count the number of falling edges in a signal applied to a CLK input. The gate signal applied to the counter GATE input is of known duration. In this case, you program the counter to count falling edges at the CLK input while the gate is applied. The frequency of the input signal then equals the count value divided by the gate period. Figure 3-19 shows the connections for a frequency measurement application. You can also use a second counter to generate the gate signal in this application. In this case, program the second counter for a one-shot mode, which requires an external inverter to make the output pulse of the second counter active high.

DAQPad-1200 User Manual 3-24 © National Instruments Corporation

Chapter 3 Signal Connections

+5 V

10 kΩ

CLK

OUT

GATE

Signal

Source

I/O Connector

Gate

Source

Counter

DGND

DAQPad-1200 Unit

Figure 3-19. Frequency Measurement Application

The GATE, CLK, and OUT signals for counters B1 and B2 are available at the I/O front connector. The GATE and CLK pins are internally pulled up to +5 V through a 10 kΩ resistor. Refer to Appendix A, Specifications, for signal voltage and current specifications.

Signal Connections Chapter 3

Figure 3-20 shows the timing requirements for the GATE and CLK input signals and the timing specifications for the OUT output signals of the 82C53.

CLK

GATE

OUT

gsu

pwh

pwl

gsu

gwh

gwl

outg

outc

clock period clock high level clock low level gate setup time gate hold time gate high level gate low level output delay from clock output delay from gate

outg

gwh

pwh

380 ns minimum 230 ns minimum 150 ns minimum 100 ns minimum 50 ns minimum 150 ns minimum 100 ns minimum 300 ns maximum 400 ns maximum

pwl

outc

gwl

Figure 3-20. General-Purpose Timing Signals

The GATE and OUT signals in Figure 3-20 are referenced to the rising edge of the CLK signal.

Power Connections

Pin 49 of the I/O connector supplies +5 V from the DAQPad-1200 power supply. This pin is referenced to DGND and you can use the +5 V to power external digital circuitry.

• Power rating 400 mA at +5 V max

Warning: Do not directly connect this +5 V power pin to any other voltage source on the

DAQPad-1200 or any other device. Doing so can damage the DAQPad-1200 or your PC. National Instruments is power connections.

DAQPad-1200 User Manual 3-26 © National Instruments Corporation

NOT liable for any damage due to incorrect

Chapter 3 Signal Connections

Pin 49 is fused for up to 400 mA. Shorting pin 49 to a ground will not damage the DAQPad-1200. If you do not receive +5 V from pin 49 of the I/O connector, make sure that the front panel rocker switch is turned on and check for any shorts between the +5 V power pin and ground.

Note: You can replace a blown fuse with the spare fuse located on the printed wire board by

removing the two rear panel screws. However, we recommend that you contact National Instruments. The DAQPad-1200 uses a 400 mA, 63 V quick-acting surface mount fuse from Schurter.

Field Wiring Considerations

Environmental noise can seriously affect the accuracy of measurements made with your DAQPad-1200 if you do not take proper care when running signal wires between signal sources and the board. The following recommendations apply mainly to analog input signal routing to the board, although they also apply to signal routing in general.

You can minimize noise pickup and maximize measurement accuracy by taking the following precautions:

• Use differential analog input connections to reject common-mode noise.

• Use individually shielded, twisted-pair wires to connect analog input signals to the

DAQPad-1200. With this type of wire, the signals attached to the ACH+ and ACH- 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 board carefully. Keep cabling away from noise sources. The most

common noise source in a PC data acquisition system is the video monitor. Separate the monitor from the analog signals as much as possible.

The following recommendations apply for all signal connections to your DAQPad-1200:

• Separate DAQPad-1200 signal lines from high-current or high-voltage lines. These lines are

capable of inducing currents in or voltages on the DAQPad-1200 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.

Chapter 4 Calibration

This chapter discusses the calibration procedures for the DAQPad-1200 analog I/O circuitry. However, the DAQPad-1200 is factory calibrated, and National Instruments can recalibrate your unit if needed. To maintain the 12-bit accuracy of the DAQPad-1200 analog input and analog output circuitry, recalibrate at 6 month intervals.

There are three ways to perform calibrations.

• Use the NI-DAQ SCXI_1200_Calibrate function. (This function is also used for the

SCXI-1200 module, which is functionally equivalent to the DAQPad-1200.) This is the simplest method.

• Use the NI-DAQ functions to write to the calibration DACs and the EEPROM.

• Use your own register-level writes to the calibration DACs and the EEPROM. To accomplish calibration using the last two methods, you need to know the details of the

calibration process. This information is in the Theory of Operation chapter of the DAQPad-1200 Register-Level Programmer Manual.

The DAQPad-1200 is software calibrated, therefore there are no calibration trimpots. The unit is shipped with a utility software for calibration. The calibration process involves reading offset and gain errors from the analog input and analog output sections and writing values to the appropriate calibration DACs to null the errors. There are four calibration DACs associated with the analog input section and four calibration DACs associated with the analog output section, two for each output channel. After the calibration process is complete, each calibration DAC is at a known value. Because these values are lost when the board is powered down, they are also stored in the onboard EEPROM for future reference.

The factory information occupies one half of the EEPROM and is write protected. The lower half of the EEPROM contains user areas for calibration data. There are six different user areas. When the DAQPad-1200 is powered on, or the conditions under which it is operating change, you must load the calibration DACs with the appropriate calibration constants.

If you use the DAQPad-1200 with NI-DAQ and LabVIEW or LabWindows/CVI, the factory calibration constants are automatically loaded into the calibration DAC the first time a function pertaining to the DAQPad-1200 is called, and then each time you change your configuration (which includes gain). You can instead choose to load the calibration DACs with calibration constants from the user areas in the EEPROM or you can recalibrate the DAQPad-1200 and load these constants directly into the calibration DACs. Calibration software is included with the DAQPad-1200 as part of the NI-DAQ software.

Calibration Chapter 4

Calibration at Higher Gains

The DAQPad-1200 has a maximum gain error of 0.5%. This means that if the board is calibrated at a gain of 1, and if the gain is switched to 100, a maximum of 50 mV error may result in the reading. Therefore, when you are recalibrating the DAQPad-1200, you should perform gain calibration at all other gains (2, 5, 10, 20, 50, and 100), and store the corresponding values in the user gain calibration data area of the EEPROM, thus ensuring a maximum error of

0.02 % at all gains.

Calibration Equipment Requirements

The equipment you use to calibrate the DAQPad-1200 should have a ±0.001% rated accuracy, which is 10 times as accurate as the DAQPad-1200. However, calibration with only four times the accuracy as the DAQPad-1200 and a ±0.003% rated accuracy are acceptable. The inaccuracy of the calibration equipment results only in gain error; offset error is unaffected.

Calibrate the DAQPad-1200 to a measurement accuracy of ±0.5 LSBs, which is within ±0.012% of its input range.

For analog input calibration, use a precision DC voltage source, such as a calibrator, with the following specifications.

Voltage 0 to 10 V Accuracy ±0.001% standard

±0.003% acceptable

Using the Calibration Function

NI-DAQ contains the SCXI_1200_Calibrate function, with which you can either load the calibration DACs with the factory constants or the user defined constants stored in the EEPROM, or perform your own calibration and directly load these constants into the calibration DACs. To use the SCXI_1200_Calibrate function for analog input calibration, you must ground an analog input channel at the front connector (for offset calibration) and apply an accurate voltage reference to another input channel (for gain calibration). For analog output calibration, the DAC0 and DAC1 outputs must be wrapped back and applied to two other analog input channels.

When you perform analog input calibration, you must first configure the ADC for referenced single-ended (RSE) mode and for the correct polarity at which you want to perform data acquisition. When you perform analog output calibration, you must first configure the analog input circuitry for RSE and for bipolar polarity, and you must configure the analog output circuitry for the correct polarity at which you want to perform output waveform generation. Refer to the NI-DAQ User Manual for PC Compatibles for more details on the SCXI_1200_Calibrate function.

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

Appendix A Specifications

This appendix lists the specifications of the DAQPad-1200. These specifications are typical at 25° C unless otherwise stated. The operating temperature range is 0° to 50° C.

Analog Input

Input Characteristics

Number of channels Eight single-ended, four differential, software

selectable Type of ADC Successive approximation Resolution 12 bits, 1 in 4,096 Conversion time (including acquisition time) 8.5 µs

Input signal ranges

Analog Input

Signal Gain

(Software

Selectable)

1 ±5 V 0 to 10 V 2 ±2.5 V 0 to 5 V 5 ±1 V 0 to 2 V 10 ±500 mV 0 to 1 V 20 ±250 mV 0 to 500 mV 50 ±100 mV 0 to 200 mV 100 ±50 mV 0 to 100 mV

Input coupling DC Max working voltage Input average should remain within 7 V of ground Overvoltage protection ±42 V powered on, ±15 V powered off

Inputs protected ACH0..ACH7 FIFO buffer size 2,048 samples Data transfers Interrupts, programmed I/O Minimum DAQ Rate 1 sample every 35 minutes

Analog Input Signal Ranges

(Software Selectable)

Bipolar Unipolar

Specifications Appendix A

Maximum Sustained DAQ Rates

Acquisition Gain Rate

Mode Setting

Single

channel

Multiple

channel

1, 2, 5, 10,

20, 50, 100

1, 2, 5, 10

20 50

100

Transfer Characteristics

Relative accuracy (nonlinearity) ±0.5 LSB typ, ±1.5 LSB max INL ±0.5 LSB typ, ±1 LSB max DNL ±0.5 LSB typ, ±1 LSB max No missing codes 12 bits, guaranteed Offset error

After calibration, at all gains ±(5 µV + 0.36 mV/gain) max

Before calibration, at all gains ±(15 mV + 150 mV/gain) max Offset adjustment range ±37 mV max Gain error

After calibration, at all gains 0.020% of reading max

Before calibration

Gain = 1 2% of reading max Gain ≠1 with gain error adjusted to 0 at gain = 1 0.5% of reading max

Gain adjustment range ±25 mV max

EPP

Mode

100 kS/s 25 kS/s

83.3 kS/s

62.5 kS/s

55.5 kS/s 25 kS/s

Centronics

Mode

25 kS/s 25 kS/s 25 kS/s 25 kS/s

Amplifier Characteristics

Input bias current 200 pA max Input offset current 100 pA max Input impedance 100 GΩ in parallel with 45 pF

CMRR

Gain CMRR

DC to 60 Hz

1 2 5

10 to 100

60 dB 66 dB 74 dB 80 dB

Dynamic Characteristics

Analog input bandwidth

Gain Single channel bandwidth

1 to 10

20 50

100

400 kHz 200 kHz

80 kHz 40 kHz

Typical timing data observed in LabVIEW on a 486 DX2/66 MHz PC using a Trunknet plug-in Centronics

parallel port card and a FarPoint F/Port plug-in enhanced parallel port card.

Appendix A Specifications

Settling time to full-scale step

System noise (including quantization

Gain Settling time to 0.012% (±0.5 LSB)

2–50

100

Gain Dither off Dither on

accuracy

12 µs

16 µs typ, 18 µs max

40 µs

error)

1 to 50

100

0.3 LSB rms

0.6 LSB rms

0.8 LSB rms

Stability

Recommended warm-up time 15 min Offset temperature coefficient ±(20 + 100/gain) µV/°C Gain temperature coefficient ±50 ppm/°C

Explanation of Analog Input Specifications

Relative accuracy is a measure of the linearity of an ADC. However, relative accuracy is a tighter specification than a nonlinearity specification. Relative accuracy indicates the maximum deviation from a straight line for the analog-input-to-digital-output transfer curve. If an ADC has been calibrated perfectly, then this straight line is the ideal transfer function, and the relative accuracy specification indicates the worst deviation from the ideal that the ADC permits.

A relative accuracy specification of ±1 LSB is roughly equivalent to (but not the same as) a ±0.5 LSB nonlinearity or integral nonlinearity specification because relative accuracy encompasses both nonlinearity and variable quantization uncertainty, a quantity often mistakenly assumed to be exactly ±0.5 LSB. Although quantization uncertainty is ideally ±0.5 LSB, it can be different for each possible digital code and is actually the analog width of each code. Thus, it is more specific to use relative accuracy as a measure of linearity than it is to use what is normally called nonlinearity, because relative accuracy ensures that the sum of quantization uncertainty and A/D conversion error does not exceed a given amount.

Integral nonlinearity (INL) in an ADC is an often ill-defined specification that is supposed to indicate a converter’s overall A/D transfer linearity. The manufacturer of the ADC chip used by National Instruments on the DAQPad-1200 specifies its integral nonlinearity by stating that the analog center of any code will not deviate from a straight line by more than ±1 LSB. This specification is misleading because although a particularly wide code’s center may be found within ±1 LSB of the ideal, one of its edges may be well beyond ±1.5 LSB; thus, the ADC would have a relative accuracy of that amount. National Instruments tests its boards to ensure that they meet all three linearity specifications defined in this appendix.

Differential nonlinearity (DNL) is a measure of deviation of code widths from their theoretical value of 1 LSB. The width of a given code is the size of the range of analog values that can be input to produce that code, ideally 1 LSB. A specification of ±1 LSB differential nonlinearity ensures that no code has a width of 0 LSBs (that is, no missing codes) and that no code width exceeds 2 LSBs.

Specifications Appendix A

System noise is the amount of noise seen by the ADC when there is no signal present at the input

of the board. The amount of noise that is reported directly (without any analysis) by the ADC is not necessarily the amount of real noise present in the system, unless the noise is considerably greater than 0.5 LSB rms. Noise that is less than this magnitude produces varying amounts of flicker, and the amount of flicker seen is a function of how near the real mean of the noise is to a code transition. If the mean is near or at a transition between codes, the ADC flickers evenly between the two codes, and the noise is very near 0.5 LSB. If the mean is near the center of a code and the noise is relatively small, very little or no flicker is seen, and the noise reported by the ADC as nearly 0 LSB. From the relationship between the mean of the noise and the measured rms magnitude of the noise, the character of the noise can be determined. National Instruments has determined that the character of the noise in the DAQPad-1200 is fairly Gaussian, so the noise specifications given are the amounts of pure Gaussian noise required to produce our readings.

Explanation of Dither

The dither circuitry, when enabled, adds approximately 0.5 LSB rms of white Gaussian noise to the signal to be converted to the ADC. This addition is useful for applications involving averaging to increase the resolution of the DAQPad-1200 to more than 12 bits, as in calibration. In such applications, which are often lower frequency in nature, noise modulation is decreased and differential linearity is improved by the addition of the dither. For high-speed 12-bit applications not involving averaging, dither should be disabled because it only adds noise.

When taking DC measurements, such as when calibrating the board, enable dither and average about 1,000 points to take a single reading. This process removes the effects of 12-bit quantization and reduces measurement noise, resulting in improved resolution. Dither, or additive white noise, has the effect of forcing quantization noise to become a zero-mean random variable rather than a deterministic function of input. For more information on the effects of dither, see “Dither in Digital Audio” by John Vanderkooy and Stanley P. Lipshitz, Journal of the Audio Engineering Society, Vol. 35, No. 12, Dec. 1987.

Explanation of DAQ Rates

Maximum DAQ rates (number of samples per second) are determined by the conversion period of the ADC plus the sample-and-hold acquisition time, which is specified at 8.5 µs. For single channel, sustained data acquisition, the maximum DAQ rate is limited by the speed of the parallel port, 100 kS/s for EPP and 25 kS/s for Centronics. During multiple-channel scanning, the DAQ rates are further limited by the settling time of the input multiplexers and programmable gain amplifier. After the input multiplexers are switched, the amplifier must be allowed to settle to the new input signal value to within 12-bit accuracy. The settling time is a function of the gain selected.

Appendix A Specifications

Analog Output

Output Characteristics

Number of output channels Two single ended Resolution 12 bits, 1 part in 4,096 Update rate

Type of DAC Double-buffered Data transfers Interrupts, programmed I/O

Transfer Characteristics

Relative accuracy (INL) ±0.25 LSB typ, ±0.50 LSB max DNL ±0.25 LSB typ, ±0.75 LSB max Monotonicity 12 bits, guaranteed Offset error

After calibration ±0.2 mV max Before calibration ±50 mV max

Offset adjustment range, min ±37 mV Gain error

After calibration 0.004% of reading max Before calibration ±1% of reading max

Gain adjustment range, min ±100 mV

8 kS/s in EPP mode, 4 kS/s with standard

Centronics port

Voltage output

Ranges 0 to +10 V, ±5 V, software selectable Output coupling DC Output impedance 0.2 Ω Current drive ±2 mA Protection Short circuit to ground Power-on state 0 V in bipolar mode, 5 V in unipolar mode

Dynamic Characteristics

Settling time to 0.012% 6 µs for 10 V step Slew rate 10 V/µs Offset temperature coefficient ±60 µV/°C Gain temperature coefficient ±10 ppm/°C

Explanation of Analog Output Specifications

Relative accuracy in a D/A system is the same as nonlinearity because no uncertainty is added due to code width. Unlike an ADC, every digital code in a D/A system represents a specific analog value rather than a range of values. The relative accuracy of the system is therefore limited to the worst-case deviation from the ideal correspondence (a straight line), excepting noise. If a D/A system has been calibrated perfectly, then the relative accuracy specification reflects its worst-case absolute error.

Differential nonlinearity (DNL) in a D/A system is a measure of deviation of code width from 1 LSB. In this case, code width is the difference between the analog values produced by consecutive digital codes. A specification of ±1 LSB differential nonlinearity ensures that

Typical timing data observed in LabVIEW on a 486 DX2/66 MHz PC using a Trunknet plug-in Centronics

parallel port card and a FarPoint F/Port plug-in enhanced parallel port card.

Specifications Appendix A

the code width is always greater than 0 LSBs (guaranteeing monotonicity) and is always less than 2 LSBs.

Digital I/O

Number of channels 24 Compatibility TTL Digital logic levels

Level Min Max

Input low voltage Input high voltage

Output low voltage (2.5 mA) Output high voltage (-2.5 mA) Absolute max voltage

-0.3 V

2.2 V –

3.7 V

-0.5 V

Handshaking 3 wire, 2 ports Power-on state Inputs Data Transfers Programmed I/O, interrupts

Timing I/O

Number of channels Three 16-bit counter/timers (uses two 82C53 STCs) Resolution counter/timers 16 bits Compatibility TTL, counter gate and clock inputs are pulled up

with 10 kΩ resistors onboard.

Base clock available 2 MHz Base clock accuracy ±0.01% Max clock frequency 8 MHz Min clock pulse duration 60 ns Min gate pulse duration 50 ns Digital logic levels

0.8 V

5.3 V

0.4 V –

5.5 V

Level Min Max

Input low voltage Input high voltage

Output low voltage (4 mA) Output high voltage (-1 mA) Absolute max voltage

-0.3 V

2.2 V –

3.7 V

-0.5 V

0.8 V

5.3 V

0.4 V –

5.5 V

Parallel Port

Types Compatible with Centronics and

Enhanced Parallel Port (EPP)

Throughput

Typical timing data observed in LabVIEW on a 486 DX2/66 MHz PC using a Trunknet plug-in Centronics

parallel port card and a FarPoint F/Port plug-in enhanced parallel port card.

50 kBytes/s Centronics 200 kBytes/s EPP

Appendix A Specifications

Physical

Dimensions 1.5 by 5.8 by 8.4 in. (3.8 x 14.6 x 21.3 cm) Connectors 50-pin male DIN C front I/O connector

25-pin female D-sub rear connectors

Weight 1.7 lb (0.77 kg)

Power Requirements

Voltage 9 to 42 V Reverse Voltage Protection -42 VDC max Power consumption 250 mA at 12 VDC +5 V I/O connector (pin 49) Protected by 400 mA, 63 V quick-acting surface

mount Schurter fuse

Max discharge time with

BP-1 battery pack 11 hours unloaded

5 hours loaded at 350 mA from +5 V I/O connector

Environment

Operating temperature 0° to 50° C Storage temperature -55° to 70° C Relative humidity 5% to 90% noncondensing

Appendix B Parallel Port Configuration Troubleshooting

This appendix contains installation troubleshooting information.

1. The configuration utility (WDAQCONF for Windows and DAQCONF for DOS) reports an error when I try to save the settings.

Check the following items if you receive a base address error. a. Make sure your chassis is switched on and the screws of the cable are tightly fastened. b. Make sure you have connected the parallel port cable to port A of the DAQPad-1200. c. Check that your base address is correct. This can be done either by checking your

computer technical manual or, in some cases, by checking the base address jumper. In Windows applications, you may have a Hardware Control panel that will allow you to enable and disable the parallel port. Common parallel port addresses are 0x378, 0x278, 0x3BC, 0x280, and 0x290.

Note: If your parallel port address does not appear under the Base Addr window in

WDAQCONF, you must turn off the Auto Test option under the Options menu in the main window to access the other parallel port addresses.

d. Check that you are using the included 1 m parallel port cable. If you suspect that you

have a bad parallel port cable, replace with a new cable or one that you know works with another peripheral. If you are using another parallel port cable, check to make sure it meets the required specifications (see the last note below).

e. If you are still having problems, please report the computer make and model number to

National Instruments. If you have a noncompatible parallel port and you have an available slot for a plug-in board, try using the Far Point EPP card described in the

Optional Equipment section of Chapter 1, Introduction. Check the following items if you receive an interrupt conflict error. a. IRQ levels 7 and 5 are the most common interrupt levels reserved for the parallel port.

Try saving your configuration for both IRQ7 and IRQ5.

Parallel Port Configuration Troubleshooting Appendix B

Note: If either IRQ level 7 or 5 are unselectable under the IRQ menu in WDAQCONF,

then another National Instruments board is using this interrupt. You will have to free the appropriate IRQ level to allocate it for your parallel port.

b. You may have an interrupt conflict with a non-National Instruments device. If you have

installed a PCMCIA card or a plug-in board, you will have to ensure that IRQ5 or IRQ7

have not been allocated for these devices.

Note: For some PCMCIA cards installed with Cardware, it may be possible to exclude

your parallel port interrupt level by including the line XIRQ=7, E for IRQ 7 or XIRQ=5, E for IRQ 5 in the cardware.ini file.

c. You may have an interrupt conflict with a Windows-based application. You will have to

ensure that IRQ5 or IRQ7 have not been allocated for this application. One place to

search is your system.ini file under Windows. d. If you are still having problems, please report the computer make and model number to

National Instruments.

2. The configuration utility works fine when I use a 1 m parallel port cable but reports an error when I try to use a longer parallel port cable.

a. Ensure that your parallel port cable meets the required specifications. (See the last note

below.)

b. You may have to use a unidirectional parallel port extender in order to achieve long

distance solutions (one such extender is made by BRAVO Communications). Your parallel port will be recognized as a Centronics port with this extender.

Note: National Instruments does not guarantee functionality with parallel port cables

longer than 2 m.

3. I have an EPP port, but the configuration utility reports that I have a Centronics port when I try to save the configuration settings.

a. You may have to enable your parallel port as an EPP port. Check for such utilities and

ensure that your port is configured for EPP.

b. It is possible that your DAQPad-1200 and NI-DAQ software are not compatible with

your EPP port. In this case, your parallel port will be treated as a Centronics port.

Parallel Port Cable Specifications

• Unbalanced impedance of each signal and ground pair of 62 Ω ±6 Ω, 4–16 MHz

• Unbalanced capacitance of each cable pair less than 107 pF/m at 1 MHz

• DC resistance of each cable wire less than 0.22 Ω/m

• Total propagation delay less than 150 ns

Appendix C Customer Communication

For your convenience, this appendix contains forms to help you gather the information necessary to help us solve technical problems you might have as well as a form you can use to comment on the product documentation. Filling out a copy of the Technical Support Form before contacting National Instruments helps us help you better and faster.

National Instruments provides comprehensive technical assistance around the world. In the U.S. and Canada, applications engineers are available Monday through Friday from 8:00 a.m. to 6:00 p.m. (central time). In other countries, contact the nearest branch office. You may fax questions to us at any time.

Corporate Headquarters

(512) 795-8248 Technical support fax: (800) 328-2203

(512) 794-5678

Branch Offices Phone Number Fax Number

Australia 03 9 879 9422 03 9 879 9179 Austria 0662 45 79 90 0 0662 45 79 90 19 Belgium 02 757 00 20 02 757 03 11 Canada Ontario) 519 622 9310 519 622 9311 Canada (Quebec) 514 694 8521 514 694 4399 Denmark 45 76 26 00 45 76 71 11 Finland 90 527 2321 90 502 2930 France 1 48 14 24 24 1 48 14 24 14 Germany 089 741 31 30 089 714 60 35 Hong Kong 2645 3186 2686 8505 Italy 02 48301892 02 48301915 Japan 03 5472 2970 03 5472 2977 Korea 02 596 7456 02 596 7455 Mexico 95 800 010 0793 05 404 0890 Netherlands 03480 33466 03480 30673 Norway 32 84 84 00 32 84 86 00 Singapore 2265886 2265887 Spain 91 640 0085 91 640 0533 Sweden 08 730 49 70 08 730 43 70 Switzerland 056 20 51 51 056 20 51 55 Taiwan 02 377 1200 02 737 4644 U.K. 01635 523545 01635 523154

Technical Support Form

Photocopy this form and update it each time you make changes to your software or hardware, and use the completed copy of this form as a reference for your current configuration. Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently.

If you are using any National Instruments hardware or software products related to this problem, include the configuration forms from their user manuals. Include additional pages if necessary.

Name Company Address

Fax ( ) Phone ( ) Computer brand Model Processor

Operating system Speed MHz RAM MB Display adapter Mouse yes no Other adapters installed Hard disk capacity MB Brand Instruments used

National Instruments hardware product model Revision

Configuration

National Instruments software product Version

Configuration

The problem is

List any error messages

The following steps will reproduce the problem

DAQPad-1200 Hardware and Software Configuration Form

Record the settings and revisions of your hardware and software on the line to the right of each item. Complete a new copy of this form each time you revise your software or hardware configuration, and use this form as a reference for your current configuration. Completing this form accurately before contacting National Instruments for technical support helps our applications engineers answer your questions more efficiently.

National Instruments Products

• Interrupt Level of parallel port ______________________________________________

• Analog Output Channel 0 Configuration ______________________________________________ (Reset condition—Bipolar)

• Analog Output Channel 1 Configuration ______________________________________________ (Reset condition—Bipolar)

• Analog Input Configuration ______________________________________________ (Reset condition—Bipolar)

• NI-DAQ or LabWindows Version ______________________________________________

Other Products

• Microprocessor ______________________________________________

• Clock Frequency ______________________________________________

• Computer Make and Model ______________________________________________

• Type of Video Board Installed ______________________________________________

• Operating System ______________________________________________

• Operating System Version ______________________________________________

• Programming Language ______________________________________________

• Programming Language Version ______________________________________________

• Other Boards in System ______________________________________________

• Interrupt Level of Other Boards ______________________________________________

Documentation Comment Form

National Instruments encourages you to comment on the documentation supplied with our products. This information helps us provide quality products to meet your needs.

Title: DAQPad-1200 User Manual Edition Date: November 1995 Part Number: 371351A-01 Please comment on the completeness, clarity, and organization of the manual.

If you find errors in the manual, please record the page numbers and describe the errors.

Thank you for your help. Name Title Company Address

Phone ( ) Mail to: Technical Publications Fax to: Technical Publications

National Instruments Corporation National Instruments Corporation 6504 Bridge Point Parkway (512) 794-5678 Austin, TX 78730-5039

Glossary

Prefix Meaning Value

p- picon- nanoµ- micro-

m- milli-

k- kilo-

M- mega-

10 10 10

10 10

-12

-9

-6

-3 3 6

˚ degrees > greater than ≥ greater than or equal to < less than

- negative of, or minus Ω ohms % percent ± plus or minus + positive of, or plus +5 V +5 Volts signal A amperes ACH <0..7> Analog Channel 0 through 7 signals ACK* Acknowledge Input signal A/D analog-to-digital ADC analog-to-digital converter AGND Analog Ground signal AISENSE/AIGND Analog Input Sense/Analog Input Ground signal ANSI American National Standards Institute AWG American Wire Gauge C Celsius CLKB1, CLKB2 Counter B1, B2 Clock signals cm centimeters CNTINT Counter Interrupt signal D/A digital-to-analog D*/A Data/Address signal DAC digital-to-analog converter DAC OUTPUT UPDATE DAC output update signal DACWRT DAC Write signal DAQ data acquisition DAQD*/A Data Acquisition Board Data/Address Line signal DAC0OUT, DAC1OUT Digital-to-Analog Converter 0, 1 Output signals DATA Data Lines at the Specified Port signal dB decibels DGND Digital Ground signal

Glossary

DIFF differential DIN Deutsche Industrie Norme DMA direct memory access EEPROM electrically erased programmable read-only memory EPP Enhanced Parallel Port EXTCONV* External Convert signal EXTTRIG External Trigger signal EXTUPDATE* External Update signal ft feet GATB <0..2> Counter B0, B1, B2 Gate signals hex hexadecimal IBF Input Buffer Full signal in. inches INTR Interrupt Request signal I/O input/output LSB least significant bit m meters max maximum MB megabytes of memory min minutes MIO multifunction I/O MSB most significant bit NRSE nonreferenced single-ended OBF* Output Buffer Full signal OUTB0, OUTB1 Counter B0, B1 Output signals PA, PB, PC <0..7> Port A, B, or C 0 through 7 signals POSTTRIG Posttrigger mode PRETRIG Pretrigger mode RD* Read signal R

EXT

external resistance

RSE referenced single-ended RTSI Real-Time System Integration s seconds SCXI Signal Conditioning eXtensions for Instrumentation (bus) SDK Software Developer's Kit SERCLK Serial Clock signal SERDATIN Serial Data In signal SERDATOUT Serial Data Out signal SLOT0SEL* Slot 0 Select signal SPICLK Serial Peripheral Interface Clock signal SS* Slot-select signal STB Strobe Input signal TTL transistor-transistor logic typ typical UP/BP* Unipolar/bipolar bit V volts

V V V

in cm diff

positive/negative input voltage common-mode noise differential input voltage

Glossary

EXT

external voltage

VI virtual instrument V

measured voltage

Vrms volts, root-mean-square V

signal source

W watts WRT* Write signal

Index

Numbers

+5 V signal, 3-3

ACH<0..7> signal

definition, 3-3

input ranges and maximum ratings, 3-4 ACK* signal, 3-16 AGND signal, 3-3 AISENSE/AIGND signal

definition, 3-3

using for general analog power ground

tie, 3-4

analog I/O configuration

analog I/O settings

default settings (table), 2-2 reset conditions, 2-2

analog input modes

DIFF, 2-3 (table), 2-4 NRSE, 2-3 (table), 2-4

RSE, 2-3 (table), 2-4 analog input polarity, 2-3 analog output polarity, 2-2

analog input modes. See analog I/O

configuration.

analog input signal connections

bipolar analog input signal range versus

gain (table), 3-4

common-mode signal rejection, 3-12

to 3-13

differential connections, 3-8

floating signal sources, 3-9 to 3-10

grounded signal sources, 3-8 to 3-9

single-ended connections, 3-10

to 3-11

exceeding maximum input voltage

ratings, 3-4 floating signal sources, 3-6 ground-referenced signal sources, 3-6 input configurations, 3-6 to 3-13 input ranges and maximum ratings, 3-4 instrumentation amplifier (figure), 3-5

pins, 3-3 recommended input configurations

(illustrations), 3-7

single-ended connections, 3-10

floating signal sources (RSE

configuration), 3-11

grounded signal sources (NRSE

configuration), 3-12 types of signal sources, 3-6 unipolar analog input signal range versus

gain (table), 3-5 analog input specifications, A-1 to A-4 analog output signal connections, 3-13

to 3-14

analog output specifications, A-5

BP-1 battery pack, 1-4

cables, custom, 1-5 calibration

equipment requirements, 4-2 higher gains, 4-2 methods, 4-1 onboard EEPROM, 4-1 overview, 4-1 using the SCXI_1200_Calibrate

function, 4-2 CLK signals

general-purpose timing signal

connections, 3-23 to 3-26

timing requirements signals

(illustration), 3-26 CLKB1 signal, 3-3 CLKB2 signal, 3-3 CNTINT signal, 3-22 common-mode signal rejection

considerations, 3-12 to 3-13

configuration

analog I/O settings

Index

default settings (table), 2-2 reset conditions, 2-2

analog input modes

DIFF, 2-3 (table), 2-4 NRSE, 2-3 (table), 2-4

RSE, 2-3 (table), 2-4 analog input polarity, 2-3 analog output polarity, 2-3 application software configuration, 2-1 exceeding maximum ratings

(warning), 2-2 parallel port, 2-2, B-1 requirements, 2-2

counter 0 on 82C53(A) counter/timer, 3-20 counter 1 on 82C53(A) counter/timer, 3-20 custom cables, 1-5 customer communication, xi, C-1

DAC0OUT signal, 3-3 DAC1OUT signal, 3-3 DACWRT signal, 3-22 DAQ and general-purpose timing signal

connections

DAQ timing connections, 3-20 to 3-23 general-purpose timing connections,

3-23 to 3-26 pins, 3-19 to 3-20 power connections, 3-26 to 3-27

DAQPad-1200. See also configuration.

definition, 1-1 installation, 2-1 kit contents, 1-2 optional equipment, 1-5

custom cables, 1-5

Enhanced Parallel Port (EPP), 1-5 overview, 1-1 software programming choices

LabVIEW and LabWindows, 1-2

NI-DAQ driver software, 1-3

DAQ timing connections. See also general-

purpose timing signal connections.

EXTCONV* signal, 3-20, 3-21 EXTCONV* signal timing

(illustration), 3-20

EXTTRIG signal, 3-20 to 3-21

EXTUPDATE* signal, 3-22 to 3-23 interval scanning, 3-22 multiple-channel interval scanning

(illustration), 3-22 pins, 3-19 posttrigger and pretrigger modes, 3-20

to 3-22 posttrigger timing (illustration), 3-21 pretrigger timing (illustration), 3-21 sample counter, 3-20 sample-interval counter, 3-20 waveform generation timing sequence,

3-22 to 3-23

DATA signal, 3-17 DGND signal, 3-3 DIFF input

configuration, 2-4 definition (table), 2-3 recommended input configurations

(illustration), 3-7

differential connections

DIFF configuration, 3-8 floating signal sources, 3-9 to 3-10 ground-referenced signal sources, 3-8

to 3-9 purpose and use, 3-8

digital I/O signal connections

illustration, 3-15 pins, 3-14 port C pin connections, 3-16 signal assignments (table), 3-3 specifications and ratings, 3-14 to 3-16 timing specifications, 3-16 to 3-17

mode 1 input timing, 3-17 mode 1 output timing, 3-18

mode 2 bidirectional timing, 3-19 digital I/O specifications, A-6 documentation

conventions used in manual, x National Instruments documentation, x organization of manual, ix related documentation, xi

Enhanced Parallel Port (EPP), adding, 1-5 environment specifications, A-7 event-counting

Index

general-purpose timing signal

connections, 3-23

with external switch gating

(illustration), 3-24

EXTCONV* signal

definition, 3-3 interval scanning data acquisition, 3-22 maximum voltage input rating, 3-23 timing requirements (illustration), 3-20

EXTTRIG signal

data acquisition timing, 3-20 to 3-22 definition, 3-3 maximum voltage input rating, 3-23

EXTUPDATE* signal

data acquisition timing, 3-22 definition, 3-3 maximum voltage input rating, 3-23 waveform generation timing sequence

(illustration), 3-23

technical support, C-1 field wiring considerations, 3-27 floating signal sources

differential connections, 3-9 to 3-10 purpose and use, 3-6 single-ended connections (RSE

configuration), 3-11

frequency measurement

general-purpose timing signal

connections, 3-23 to 3-26

illustration, 3-25

front connector

exceeding maximum ratings

(warning), 3-1

pin assignments, 3-2

fuse

+5 V power supply, 3-3, 3-27, A-8

GATB0 signal, 3-3 GATB1 signal, 3-3 GATB2 signal, 3-3 GATE signals

general-purpose timing signal

connections, 3-23 to 3-26

timing requirements signals

(illustration), 3-26

general-purpose timing signal connections.

National Instruments DAQPAD-1200 User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual

Limited Warranty

Copyright

Trademarks

Contents

Figures

Tables

About This Manual

Organization of This Manual

Conventions Used in This Manual

National Instruments Documentation

Related Documentation

Customer Communication

Chapter 1 Introduction

About the DAQPad-1200

What You Need to Get Started

Software Programming Choices

LabVIEW and LabWindows/CVI Application Software

NI-DAQ Driver Software

Register-Level Programming

Optional Equipment

BP-1 Battery Pack

Adding an Enhanced Parallel Port (EPP)

Custom Cables

Chapter 2 Installation and Configuration

Hardware Installation

Configuration

Parallel Port Configuration

Analog I/O Configuration

Table 2-1. Analog I/O Settings

Analog Output Polarity

Analog Input Polarity

Analog Input Mode

Table 2-2. Analog Input Modes for the DAQPad-1200

Chapter 3 Signal Connections

Transparent Parallel Port Connector

Front Connector

Figure 3-1. DAQPad-1200 Front I/O Connector Pin Assignments

Signal Connection Descriptions

Analog Input Signal Connections

Table 3-1. Bipolar Analog Input Signal Range Versus Gain

Table 3-2. Unipolar Analog Input Signal Range Versus Gain

Figure 3-2. DAQPad-1200 Instrumentation Amplifier

Types of Signal Sources

Input Configurations

Figure 3-3. Summary of Analog Input Connections

Figure 3-4. Differential Input Connections for Grounded Signal Sources

Figure 3-5. Differential Input Connections for Floating Sources

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

Figure 3-7. Single-Ended Input Connections for Grounded Signal Sources Common-Mode Signal Rejection Considerations Figures 3-4 and 3-7 show connections for signal sources that are already referenced to some

Analog Output Signal Connections

Figure 3-8. Analog Output Signal Connections

Digital I/O Signal Connections

Figure 3-9. Digital I/O Connections

Port C Pin Connections

Table 3-3. Port C Signal Assignments

Timing Specifications

Figure 3-10. Mode 1 Timing Specifications for Input Transfers

Figure 3-11. Mode 1 Timing Specifications for Output Transfers

Figure 3-12. Mode 2 Timing Specification for Bidirectional Transfers

DAQ and General-Purpose Timing Signal Connections

DAQ Timing Connections

Figure 3-13. EXTCONV* Signal Timing

Figure 3-14. Posttrigger DAQ Timing

Figure 3-15. Pretrigger DAQ Timing

Figure 3-16. Interval-Scanning Signal Timing

Figure 3-17. EXTUPDATE* Signal Timing for Updating DAC Output

General-Purpose Timing Signal Connections

Figure 3-18. Event-Counting Application with External Switch Gating

Figure 3-19. Frequency Measurement Application

Figure 3-20. General-Purpose Timing Signals

Power Connections

Field Wiring Considerations

Chapter 4 Calibration

Calibration at Higher Gains

Calibration Equipment Requirements

Using the Calibration Function