National Instruments Corporation DAQCard-500 User manual

© Copyright 1995, 1996 National Instruments Corporation.
All Rights Reserved.
DAQCard™-500
User Manual
Multifunction I/O Card for Type II PCMCIA Bus
January 1996 Edition
Part Number 371918A-01

National Instruments Corporate Headquarters
6504 Bridge Point Parkway
Austin, TX 78730-5039
[phone]
Technical support fax: [phone]
[phone]
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Limited Warranty
The DAQCard-500 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
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OF NATIONAL INSTRUMENTS SHALL BE LIMITED TO THE AMOUNT THERETOFORE PAID BY THE CUSTOMER.
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whether in contract or tort, including negligence. Any action against National Instruments must be brought within
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to causes beyond its reasonable control. The warranty provided herein does not cover damages, defects,
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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.
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LabVIEW®, NI-DAQ®, RTSI®, and DAQCard™ are trademarks of National Instruments Corporation.
Product and company names listed are trademarks or trade names of their respective companies.

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

© National Instruments Corporation v DAQCard-500 User Manual
Contents
____________________________________________________
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 DAQCard-500...............................................................................................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
Register-Level Programming............................................................................. 1-4
Optional Equipment.......................................................................................................1-4
Unpacking......................................................................................................................1-4
Chapter 2
Installation and Configuration....................................................................................... 2-1
Installation......................................................................................................................2-1
Configuration.................................................................................................................2-2
Analog Input Configuration...............................................................................2-3
Digital I/O Configuration...................................................................................2-3
Counter Configuration.......................................................................................2-3
Chapter 3
Signal Connections............................................................................................................. 3-1
I/O Connector.................................................................................................................3-1
Signal Connection Descriptions.....................................................................................3-2
Analog Input Signal Connections......................................................................3-2
Analog Input Signal Connection Considerations...................................3-3
Types of Signal Sources.........................................................................3-3
Ground-Referenced Signal Sources...........................................3-3
Floating Signal Sources .............................................................3-3
Types of Measurement Systems ............................................................3-3
Ground-Referenced Measurement System................................3-4
Floating Measurement System...................................................3-4
Analog Input Configurations .................................................................3-4
Digital I/O Signal Connections..........................................................................3-5
Timing Connections...........................................................................................3-7
Data Acquisition Counter and Timing Connections..............................3-7
General-Purpose Counter and Timing Signal Connections...................3-7
Cabling...........................................................................................................................3-11

Contents
DAQCard-500 User Manual vi © National Instruments Corporation
Chapter 4
Theory of Operation..........................................................................................................4-1
Functional Overview......................................................................................................4-1
PCMCIA I/O Channel Interface Circuitry.....................................................................4-2
Analog Input and Data Acquisition Circuitry................................................................4-3
Analog Input Circuitry.......................................................................................4-3
Data Acquisition Timing Circuitry....................................................................4-4
Single-Channel Data Acquisition...........................................................4-4
Multichannel (Scanned) Data Acquisition.............................................4-5
Data Acquisition Rates...........................................................................4-5
Digital I/O Circuitry.......................................................................................................4-5
Timing I/O Circuitry......................................................................................................4-6
Appendix A
Specifications........................................................................................................................ A-1
Appendix B
Differences between the DAQCard-700 and the DAQCard-500.......................B-1
Appendix C
Custom Cable Design.........................................................................................................C-1
Appendix D
PC Card Questions and Answers.................................................................................. D-1
Appendix E
Power Management Modes.............................................................................................E-1
Appendix F
PSH27-50F Signal Connections.....................................................................................F-1
Appendix G
Customer Communication...............................................................................................G-1
Glossary......................................................................................................................Glossary-1
Index .................................................................................................................................Index-1

Contents
© National Instruments Corporation vii DAQCard-500 User Manual
Figures
Figure 1-1. The Relationship between the Programming Environment, NI-DAQ,
and Your Hardware..............................................................................................1-3
Figure 2-1. A Typical Configuration for the DAQCard-500 ................................................2-2
Figure 3-1. I/O Connector Pin Assignments.......................................................................... 3-1
Figure 3-2. DAQCard-500 Analog Input Connections..........................................................3-5
Figure 3-3. Digital I/O Signal Connections............................................................................3-6
Figure 3-4. EXTCONV* Signal Timing................................................................................3-7
Figure 3-5. Event-Counting Applications with External Switch Gating................................3-8
Figure 3-6. Frequency Measurement Application..................................................................3-9
Figure 3-7. General-Purpose Timing Signals......................................................................... 3-10
Figure 4-1. DAQCard-500 Block Diagram............................................................................4-1
Figure 4-2. PCMCIA I/O Interface Circuitry Block Diagram ...............................................4-2
Figure 4-3. Analog Input and Data Acquisition Circuitry Block Diagram............................4-3
Figure 4-4. Digital I/O Circuitry Block Diagram................................................................... 4-6
Figure 4-5. Timing I/O Circuitry Block Diagram..................................................................4-7
Figure 4-6. Counter Block Diagram....................................................................................... 4-7
Figure C-1. DAQCard-500 I/O Connector Pin Assignments..................................................C-2
Figure F-1. CB-50 Pin Assignments Using the PSH27-50F-D1 Cable..................................F-1
Tables
Table 3-1. Recommended Input Configurations for Ground-Referenced and
Floating Measurement Systems...........................................................................3-4
Table E-1. DAQCard-500 Power-Management Modes.........................................................E-1

© National Instruments Corporation ix DAQCard-500 User Manual
About This Manual
This manual describes the mechanical and electrical aspects of the DAQCard-500 and contains
information concerning its installation and operation. The DAQCard-500 is a compact, low-cost,
low-power analog input, digital I/O, and timing I/O board for computers that are equipped with a
Type II PCMCIA socket.
Organization of This Manual
The DAQCard-500 User Manual is organized as follows:
• Chapter 1, Introduction, describes the DAQCard-500, lists what you need to get started, your
software programming choices, and explains how to unpack the DAQCard-500.
• Chapter 2, Installation and Configuration, describes how to install and software configure the
DAQCard-500.
• Chapter 3, Signal Connections, describes the signals on the PR27-30F I/O connector and the
CB-27 connector block, optional accessories available from National Instruments.
• Chapter 4, Theory of Operation, includes an overview of the DAQCard-500 and explains the
operation of each functional unit making up the DAQCard-500.
• Appendix A, Specifications, lists the specifications of the DAQCard-500.
• Appendix B, Differences between the DAQCard-700 and the DAQCard-500, contains a
summary of differences between the DAQCard-700 and the DAQCard-500 that may be
relevant to you if you are a current DAQCard-700 user.
• Appendix C, Custom Cable Design, describes the pin connections on the DAQCard-500,
which you will need to use only if you are designing your own cable.
• Appendix D, PC Card Questions and Answers, contains a list of common questions and
answers relating to PC Card (PCMCIA) operation.
• Appendix E, Power-Management Modes, describes the power-management modes of the
DAQCard-500.
• Appendix F, PSH27-50F Signal Connections, gives the pin assignments for the CB-50 I/O
connector block when using the PSH27-50F-D1 cable with the DAQCard-500.
• Appendix G, 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 acronyms, abbreviations, metric prefixes, mnemonics, and symbols.
• The Index alphabetically lists topics covered in this manual, including the page number
where you can find the topic.
Conventions Used in This Manual
The following conventions are used in this manual:

About This Manual
DAQCard-500 User Manual x © National Instruments Corporation
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.
NI-DAQ NI-DAQ refers to the NI-DAQ software.
< > Angle brackets, < >, containing numbers separated by an ellipsis represent
a range of values associated with a bit or signal name (for example,
ACH<0..7> stands for the signals ACH0 through ACH7).
Abbreviations, acronyms, metric prefixes, mnemonics, symbols, and terms are listed in the
Glossary.
National Instruments Documentation
The DAQCard-500 User Manual is one piece of the documentation set for your data acquisition
system. You could have any of several types of manuals, depending on the hardware and
software in your system. Use the manuals you have as follows:
• Getting Started with SCXI—If you are using SCXI, this is the first manual you should read.
It gives an overview of the SCXI system and contains the most commonly needed
information for the modules, chassis, and software.
• Your SCXI user manuals—If you are using SCXI, read these manuals next for detailed
information about signal connections and module configuration. They also explain in greater
detail how the module works and contain application hints.
• Your DAQ hardware user manuals—These manuals have detailed information about the
DAQ hardware that plugs into or is connected to your computer. Use these manuals for
hardware installation and configuration instructions, specification information about your
DAQ hardware, and application hints.
• Software documentation—Examples of software documentation you may have are the
LabVIEW and LabWindows/CVI manual sets and the NI-DAQ documentation. After you
set up your hardware system, use either the application software (LabVIEW or
LabWindows/CVI) manuals or the NI-DAQ documentation to help you write your
application. If you have a large and complicated system, it is worthwhile to look through the
software documentation before you configure your hardware.

About This Manual
© National Instruments Corporation xi DAQCard-500 User Manual
• Accessory manuals—If you are using accessory products, read the terminal block and cable
assembly installation guides. They explain how to physically connect the relevant pieces of
the system. Consult these guides when you are making your connections.
• SCXI chassis manuals—If you are using SCXI, read these manuals for maintenance
information on the chassis, installation instructions, and information about making custom
modules.
Related Documentation
The following documents contain information that you may find helpful as you read this manual:
• Your NI-DAQ software documentation
• Your computer operating manual, which explains how to insert cards into the PCMCIA slot
The following National Instruments manual contains detailed information for the register-level
programmer:
• DAQCard-500 Register-Level Programmer Manual
This manual is available from National Instruments by request. If you are using NI-DAQ,
LabVIEW, or LabWindows/CVI, you should not need the register-level programmer manual.
Using NI-DAQ, LabVIEW, or LabWindows/CVI is as easy and as flexible as using the low-level
programming described in the register-level programmer manual. Refer to Software
Programming Choices in Chapter 1, Introduction, of this manual to learn more about your
programming options.
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 G, Customer
Communication, at the end of this manual.

© National Instruments Corporation 1-1 DAQCard-500 User Manual
Chapter 1
Introduction
This chapter describes the DAQCard-500, lists what you need to get started, your software
programming choices, and explains how to unpack the DAQCard-500.
About the DAQCard-500
Thank you for purchasing the National Instruments DAQCard-500. The DAQCard-500 is a low-
cost, low-power analog input, digital I/O, and timing I/O board for computers equipped with a
Type II PCMCIA slot. The board contains a 12-bit, successive-approximation ADC with eight
single-ended analog inputs, four lines of TTL-compatible digital input, and four lines of digital
output. The optional 27-pin I/O connector for the DAQCard-500 enables you to easily connect
all your signals directly to the card. The DAQCard-500 is fully software configurable and
calibrated so that you can easily install the card and begin your acquisition without having to
spend time calibrating the card.
The DAQCard-500 ships with NI-DAQ, National Instruments’ complete DAQ driver that
handles every function listed on the data sheet for our DAQ hardware. Using NI-DAQ you can
quickly and easily start your application without having to program the card on the register level.
The small size and weight of the DAQCard-500 coupled with its low-power consumption make
this board ideal for use in portable computers, making remote data acquisition practical. The
board requires very little power when operating and has a standby mode that uses even less
power, thus extending the life of your computer batteries.
In addition, the low cost of a system based on the DAQCard-500 makes it ideal for laboratory
work in industrial and academic environments. The multichannel analog input is useful in signal
analysis and data logging. The 12-bit ADC is useful in high-resolution applications such as
chromatography, temperature measurement, and DC voltage measurement. The eight TTL-
compatible digital I/O lines can be used for switching external devices such as transistors and
solid-state relays, and for reading the status of external digital logic. The DAQCard-500, used in
conjunction with your computer, is a versatile, cost-effective platform for laboratory test,
measurement, and control.
Detailed specifications for the DAQCard-500 are in Appendix A,Specifications.

Introduction Chapter 1
DAQCard-500 User Manual 1-2 © National Instruments Corporation
What You Need to Get Started
To set up and use your DAQCard-500, you will need the following:
DAQCard-500
PR27-30F I/O connector with cable (must be purchased separately)
DAQCard-500 User Manual
One of the following software packages and documentation:
NI-DAQ for PC compatibles
NI-DAQ for NEC PC-9800 Series
NI-DAQ for Macintosh
LabVIEW for Windows
LabWindows/CVI for Windows
Your computer
Software Programming Choices
There are several options to choose from when programming your National Instruments DAQ
and SCXI hardware. You can use LabVIEW, LabWindows/CVI, or NI-DAQ.
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 reduce the development time for
your data acquisition and control application.

Chapter 1 Introduction
© National Instruments Corporation 1-3 DAQCard-500 User Manual
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, 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.
NI-DAQ also internally addresses many of the complex issues between the computer and the
DAQ hardware such as programming interrupts and DMA controllers. NI-DAQ maintains a
consistent software interface among its different versions so that you can change platforms with
minimal modifications to your code. Figure 1-1 illustrates the relationship between NI-DAQ and
LabVIEW and LabWindows/CVI.
LabWindows/CVI
(PC or Sun
SPARCstation)
LabVIEW
(PC, Macintosh, or
Sun SPARCstation)
Conventional
Programming
Environment
(PC, Macintosh, or
Sun SPARCstation)
NI-DAQ
Driver Software
DAQ or
SCXI Hardware Personal
Computer or
Workstation
Figure 1-1. The Relationship between the Programming Environment,
NI-DAQ, and Your Hardware

Introduction Chapter 1
DAQCard-500 User Manual 1-4 © National Instruments Corporation
Register-Level Programming
The final option for programming any National Instruments DAQ hardware is to write register-
level software. Writing register-level programming software can be very time-consuming and
inefficient and is not recommended for most users.
Even if you are an experienced register-level programmer, 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 register-level
programming and can save weeks of development time.
Optional Equipment
Listed below are some of the optional accessories that work with the DAQCard-500. New
accessories are always being added to our product family. See your National Instruments catalog
or call the National Instruments office nearest you for more information about optional
equipment.
• PR27-30F I/O connector with .5 m or 1 m connector cable
• CB-27 I/O connector block
Unpacking
The DAQCard-500 is shipped in an antistatic vinyl case; when you are not using the
DAQCard-500, you should store it in thiscase. Because the DAQCard-500 is enclosed in a fully
shielded case, no additional electrostatic precautions are necessary. However, for your own
safety and to protect the DAQCard-500, never attempt to touch the pins of the connectors.

© National Instruments Corporation 2-1 DAQCard-500 User Manual
Chapter 2
Installation and Configuration
This chapter describes how to install and software configure the DAQCard-500.
Installation
Your computer should be equipped with Card and Socket Services 2.0 or later. The
DAQCard-500 requires a 32-byte I/O address window and one interrupt level.
This manual assumes that you are using the optional PR27-30F cable from National Instruments.
Notice that the cable is keyed so that you can insert it only one way.
Insert the DAQCard-500 and attach the I/O cable.
Your DAQCard-500 kit includes a label for the CB-27 terminal block, which is available from
National Instruments. If you are using the CB-27, attach the label to the inside cover. This label
identifies the DAQCard-500 signal connections for the CB-27.
The DAQCard-500 has two connectors–a 68-pin PCMCIA bus connector on one end and a
27-pin I/O connector on the other end. Insert the PCMCIA bus connector into any available
Type II PCMCIA slot until the connector is seated firmly. Notice that the card is keyed so that it
can be inserted only one way. If your computer supports hot insertion, you may insert or remove
the DAQCard-500 at any time, whether your computer is powered on or off.
Be very careful not to put strain on the I/O cable when inserting it into and removing it from the
DAQCard-500. Always grasp the cable by the connector you are plugging or unplugging. Never
pull directly on the I/O cable to unplug it from the DAQCard-500.
Figure 2-1 shows an example of a typical configuration.

Installation and Configuration Chapter 2
DAQCard-500 User Manual 2-2 © National Instruments Corporation
PCMCIA Socket
Portable
Computer
PR27-30F
INSERT CARD
CB-27
DAQCard
“
-500
CB-27
Figure 2-1. A Typical Configuration for the DAQCard-500
The DAQCard-500 is now installed. You are ready to make the appropriate connections to the
I/O connector cable as described in Chapter 3, Signal Connections, and to install and configure
your software.
Configuration
The DAQCard-500 is completely software configurable; refer to your software documentation to
install and configure the software.
If you are using NI-DAQ for PC compatibles or NI-DAQ for NEC PC-9800 Series computers,
refer to your NI-DAQ release notes. Find the installation and system configuration section for
your operating system and follow the instructions given there.
If you are using NI-DAQ for Macintosh, refer to the NI-DAQ documentation. Find the
installation and system configuration section for your operating system and follow the
instructions given there.
If you are using LabVIEW, the software installation instructions are in your LabVIEW release
notes. After you have installed LabVIEW, refer to the Configuring LabVIEW section of
Chapter 1 of your LabVIEW user manual for software configuration instructions.

Chapter 2 Installation and Configuration
© National Instruments Corporation 2-3 DAQCard-500 User Manual
If you are using LabWindows/CVI, the software installation instructions are in Part 1,
Introduction to LabWindows/CVI, of the Getting Started with LabWindows/CVI manual. After
you have installed LabWindows/CVI, refer to Chapter 1, Configuring LabWindows/CVI, of the
LabWindows/CVI User Manual for software configuration instructions.
If you are a register-level programmer, refer to the DAQCard-500 Register-Level Programmer
Manual.
Analog Input Configuration
The DAQCard-500 is always configured as follows:
• Single-ended input mode referenced to analog ground
• ±5 V analog input range
Digital I/O Configuration
The DAQCard-500 always uses one 4-bit digital output port and one 4-bit digital input port.
Counter Configuration
You can use the MSM82C54 counter/timers for general-purpose applications, such as pulse and
square wave generation, event counting, and pulsewidth, time-lapse, and frequency
measurement. For information about configuring the MSM82C54, see the Timing Connections
section of Chapter 3, Signal Connections.

© National Instruments Corporation 3-1 DAQCard-500 User Manual
Chapter 3
Signal Connections
This chapter describes the signals on the PR27-30F I/O connector and the CB-27 connector
block, optional accessories available from National Instruments. Appendix C, Custom Cable
Design, contains information and guidelines for the design of custom cables. Appendix F,
PSH27-50F Signal Connections, contains information for using the the PSH27-50F and the
CB-50 connector block, optional accessories available from National Instruments.
I/O Connectors
Figure 3-1 shows the pin assignments for the PR27-30F I/O connector and CB-27 connector
block. Although the pin arrangements on these connectors differ, notice that the signal names
and pin numbers are the same.
Warning: Connections that exceed any of the maximum ratings of input or output signals on
the DAQCard-500 can damage the DAQCard-500 and your computer. This
includes connecting any power signals to ground and vice versa. National
Instruments is NOT liable for any damages resulting from such signal connections.
2
4
6
8
10
12
14
16
18
11
13
15
17
20
22
24
26
28
30
ACH0
ACH2
ACH4
ACH6
+5 V
DIN0
DIN2
DOUT0
DOUT2
1MHz
CLK1
GATE2
OUT2
NC
NC
AIGND
ACH1
ACH3
ACH5
ACH7
EXTCONV*
DIN1
DIN3
DOUT1
DOUT3
DGND
OUT1
CLK2
DGND
NC
1
3
5
7
9
19
21
23
25
27
29
key
9
8
7
6
5
22
21
20
19
4
3
2
1
1
DIN1
DIN0
EXTCONV*
+5 V
ACH7
ACH6
ACH5
ACH4
ACH3
ACH2
ACH1
ACH0
AIGND
AIGND
DGND
OUT2
CLK2
GATE2
OUT1
CLK1
DGND
1 MHz
DOUT3
DOUT2
DOUT1
DOUT0
DIN3
DIN2
18
17
16
15
14
13
12
11
10
23
24
25
26
27
a. CB-27 Connector Block b. PR27-30F Cable
Figure 3-1. I/O Connector Pin Assignments

Signal Connections Chapter 3
DAQCard-500 User Manual 3-2 © National Instruments Corporation
Signal Connection Descriptions
Pin Signal Name Description
1 AIGND Analog Input Ground—This signal is the common ground tie-in point
for all analog signals.
2–9 ACH<0..7> Analog Input Channels 0 through 7—These signals are the single-ended
analog input signals.
10 +5 V +5 Volts—This pin provides +5 VDC. The +5 V supply is fused at 1 A,
which is the maximum current available.
11 EXTCONV* External Convert Signal—This input signal externally initiates an A/D
conversion.
12–15 DIN<0..3> Digital Input Data Lines—These signals are TTL-compatible, digital
input lines. DIN3 is the MSB; DIN0 is the LSB
16–19 DOUT<0..3> Digital Output Data Lines—These signals are TTL-compatible digital
output lines. DOUT3 is the MSB; DOUT0 is the LSB.
20 1 MHz 1 MHz Square Wave Output of Oscillator—This signal is a 1 MHz
square wave for use with the internal counter or external timing needs.
21, 27 DGND Digital Ground—This is the common ground tie-in point for all digital
signals.
22 CLK1 Clock Input of Counter 1—This signal is the clock input of counter 1.
23 OUT1 Output of Counter 1—This signal outputs the programmed waveform of
counter 1.
24 GATE2 Gate Input of Counter 2—This signal controls the starting, interruption,
and restarting of counter 2.
25 CLK2 Clock Input of Counter 2—This signal is the clock input of counter 2.
26 OUT2 Output of Counter 2—This signal outputs the programmed waveform of
counter 2.
28–30 NC Not Connected—These signals are not connected.
Note: An asterisk (*) indicates that the signal is active low.
The connector pins are grouped into analog input signal pins, digital I/O signal pins, and timing
I/O signal pins. Signal connection guidelines for each of these groups are included in the
following pages.
Analog Input Signal Connections
Pins 1 through 9 are analog input signal pins for the ADC. Pin 1, AIGND, is an analog common
signal. You can use these pins for a general analog power ground tie to the DAQCard-500. Pins
2 through 9 are the ACH<0..7> signal pins. These pins are tied to the analog input channels of
the DAQCard-500 through 4.7 k series resistors. These resistors limit the input current

Chapter 3 Signal Connections
© National Instruments Corporation 3-3 DAQCard-500 User Manual
to the multiplexer. The following input range and maximum ratings apply to inputs ACH<0..7>:
• Input signal range ±5 V
• Maximum input voltage rating ±25 V powered on or off
Warning: Exceeding the input signal range distorts input signals. Exceeding the maximum
input voltage rating may damage the DAQCard-500 card and the computer.
National Instruments is NOT liable for any damages resulting from any such
signal connections.
Analog Input Signal Connection Considerations
When making analog signal connections to the DAQCard-500, you should first determine
whether the signal source and the measurement system are floating or ground referenced. The
two types of signal sources are described as follows, and the types of measurement systems are
described in later sections.
Types of Signal Sources
Ground-Referenced Signal Sources
A ground-referenced signal source is one that is connected in some way to the building system
ground. Nonisolated outputs of instruments and devices that plug into the building power system
fall into this category.
The difference in ground potential between two instruments connected to the same building
power system is typically between 1 and 100 mV but can be much higher if power distribution
circuits are not properly connected.
Floating Signal Sources
A floating signal source is one that is not connected in any way to the building ground system
but rather 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. The ground reference of a floating signal must be tied to the DAQCard-500
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 provides an
isolated output falls into the floating signal source category.
Types of Measurement Systems
In addition to determining the type of signal source, you also need to determine whether your
measurement system is floating or ground referenced. These two types of measurement systems