National Instruments PC-DIO-24 User manual

© Copyright 1989, 1995 National Instruments Corporation.
All Rights Reserved.
PC-DIO-24
User Manual
Digital I/O Board for the IBM PC/XT/AT
September 1995 Edition
Part Number 320288B-01

National Instruments Corporate Headquarters
6504 Bridge Point Parkway
Austin, TX 78730-5039
[phone]
Technical support fax: [phone]
[phone]
Branch Offices:
Australia 03 9 879 9422, Austria 0662 45 79 90 0, Belgium 02 757 00 20, Canada (Ontario) 519 622 9310,
Canada (Québec) 514 694 8521, Denmark 45 76 26 00, Finland 90 527 2321, France 1 48 14 24 24,
Germany 089 741 31 30, Hong Kong 2645 3186, Italy 02 48301892, Japan 03 5472 2970, Korea 02 596 7456,
Mexico 5 202 2544, Netherlands 03480 33466, Norway 32 84 84 00, Singapore 2265886, Spain 91 640 0085,
Sweden 08 730 49 70, Switzerland 056 20 51 51, Taiwan 02 377 1200, U.K. 01635 523545

Limited Warranty
The PC-DIO-24 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®and NI-DAQ®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.

FCC/DOC Radio Frequency Interference Compliance
This equipment generates and uses radio frequency energy and, if not installed and used in strict accordance with the
instructions in this manual, may cause interference to radio and television reception. This equipment has been tested
and found to comply with the following two regulatory agencies:
Federal Communications Commission
This device complies with Part 15 of the Federal Communications Commission (FCC) Rules for a Class A digital
device. Operation is subject to the following two conditions:
1. This device may not cause harmful interference in commercial environments.
2. This device must accept any interference received, including interference that may cause undesired operation.
Canadian Department of Communications
This device complies with the limits for radio noise emissions from digital apparatus set out in the Radio
Interference Regulations of the Canadian Department of Communications (DOC).
Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant les limites applicables aux appareils
numériques de classe A prescrites dans le règlement sur le brouillage radioélectrique édicté par le ministère des
communications du Canada.
Instructions to Users
These regulations are designed to provide reasonable protection against harmful interference from the equipment to
radio reception in commercial areas. Operation of this equipment in a residential area is likely to cause harmful
interference, in which case the user will be required to correct the interference at his own expense.
There is no guarantee that interference will not occur in a particular installation. However, the chances of
interference are much less if the equipment is installed and used according to this instruction manual.
If the equipment does cause interference to radio or television reception, which can be determined by turning the
equipment on and off, one or more of the following suggestions may reduce or eliminate the problem.
• Operate the equipment and the receiver on different branches of your AC electrical system.
• Move the equipment away from the receiver with which it is interfering.
• Reorient or relocate the receiver’s antenna.
• Be sure that the equipment is plugged into a grounded outlet and that the grounding has not been defeated with a
cheater plug.
Notice to user: Changes or modifications not expressly approved by National Instruments could void the user’s
authority to operate the equipment under the FCC Rules.
If necessary, consult National Instruments or an experienced radio/television technician for additional suggestions.
The following booklet prepared by the FCC may also be helpful: How to Identify and Resolve Radio-TV
Interference Problems. This booklet is available from the U.S. Government Printing Office, Washington, DC
20402, Stock Number 004-000-00345-4.

© National Instruments Corporation vii PC-DIO-24 User Manual
Contents
About This Manual.............................................................................................................xi
Organization of This Manual .........................................................................................xi
Conventions Used in This Manual.................................................................................xii
National Instruments Documentation ............................................................................xii
Related Documentation..................................................................................................xiii
Customer Communication .............................................................................................xiii
Chapter 1
Introduction ..........................................................................................................................1-1
About the PC-DIO-24 ....................................................................................................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
Custom Cables ...................................................................................................1-4
Unpacking ......................................................................................................................1-6
Chapter 2
Configuration and Installation ......................................................................................2-1
Board Configuration ......................................................................................................2-1
Base I/O Address Settings..................................................................................2-2
Interrupt Selection..............................................................................................2-4
Interrupt Enable Settings........................................................................2-4
Interrupt Level Settings..........................................................................2-4
Installation......................................................................................................................2-5
Signal Connections ........................................................................................................2-6
I/O Connector Pin Description...........................................................................2-6
Signal Connection Descriptions.........................................................................2-7
Port C Pin Assignments .........................................................................2-7
Timing Specifications ........................................................................................2-8
Mode 1 Input Timing .............................................................................2-9
Mode 1 Output Timing ..........................................................................2-10
Mode 2 Bidirectional Timing.................................................................2-11
Chapter 3
Theory of Operation ..........................................................................................................3-1
Address Decoder............................................................................................................3-2
Bus Transceivers............................................................................................................3-2
PC I/O Channel Control Circuitry .................................................................................3-2
82C55A Programmable Peripheral Interface ................................................................3-2
Interrupt Control Circuitry.............................................................................................3-2
Digital I/O Connector.....................................................................................................3-2

Contents
PC-DIO-24 User Manual viii © National Instruments Corporation
Chapter 4
Register-Level Programming .........................................................................................4-1
Introduction....................................................................................................................4-1
82C55A Modes of Operation.........................................................................................4-1
Mode 0 ...............................................................................................................4-2
Mode 1 ...............................................................................................................4-2
Mode 2 ...............................................................................................................4-2
Single Bit Set/Reset Feature ..............................................................................4-2
Register Map..................................................................................................................4-3
Register Descriptions .....................................................................................................4-3
Single Bit Set/Reset Feature ..............................................................................4-4
Programming Considerations.........................................................................................4-5
Mode 0–Basic I/O ..............................................................................................4-5
Mode 0 Programming Example .............................................................4-6
Mode 1–Strobed Input .......................................................................................4-7
Mode 1 Input Programming Example....................................................4-9
Mode 1–Strobed Output.....................................................................................4-9
Mode 1 Output Programming Example.................................................4-11
Mode 2–Bidirectional Bus .................................................................................4-12
Mode 2 Programming Example .............................................................4-13
Interrupt Programming Examples......................................................................4-14
Interrupt Handling..........................................................................................................4-15
Appendix A
Specifications........................................................................................................................A-1
Appendix B
I/O Connector.......................................................................................................................B-1
Appendix C
OKI 82C55A Data Sheet...................................................................................................C-1
Appendix D
Customer Communication...............................................................................................D-1
Glossary............................................................................................................................Glossary-1
Index ..................................................................................................................................Index-1

Contents
© National Instruments Corporation ix PC-DIO-24 User Manual
Figures
Figure 1-1. The Relationship between the Programming Environment, NI-DAQ, and
Your Hardware...................................................................................................1-3
Figure 2-1. PC-DIO-24 Parts Locator Diagram ...................................................................2-2
Figure 2-2. Example Base I/O Address Switch Settings .....................................................2-3
Figure 2-3. Jumper Settings–PC6, PC4, PC2, and N/C........................................................2-4
Figure 2-4. Interrupt Jumper Setting for IRQ5 (Factory Setting) ........................................2-4
Figure 2-5. Digital I/O Connector Pin Assignments ............................................................2-6
Figure 3-1. PC-DIO-24 Block Diagram ...............................................................................3-1
Figure 4-1. Control-Word Formats.......................................................................................4-4
Figure B-1. PC-DIO-24 I/O Connector.................................................................................B-1
Tables
Table 2-1. PC-DIO-24 Factory-Set Jumper and Switch Settings........................................2-1
Table 2-2. Port C Signal Assignments ...............................................................................2-7
Table 4-1. PC-DIO-24 Address Map...................................................................................4-3
Table 4-2. Port C Set/Reset Control Words ........................................................................4-5
Table 4-3. Mode 0 I/O Configurations................................................................................4-6
Table 4-4. Interrupt Enable Signals for All Mode Combinations .......................................4-16
Table A-1. Maximum Average Transfer Rates for the PC-DIO-24.....................................A-2

© National Instruments Corporation xi PC-DIO-24 User Manual
About This Manual
This manual describes the mechanical and electrical aspects of the PC-DIO-24 and contains
information concerning its operation and programming. The PC-DIO-24 is a 24-bit parallel,
digital I/O interface designed around an 82C55A programmable peripheral interface (PPI). The
PC-DIO-24 is a member of the National Instruments PC Series of PC I/O Channel expansion
boards for the IBM PC computer family. These boards are designed for low-cost data acquisition
and control for applications in laboratory testing, production testing, and industrial process
monitoring and control.
This manual describes installation, basic programming considerations, and theory of operation
for the PC-DIO-24. The example programs included are written in C.
Organization of This Manual
The PC-DIO-24 User Manual is organized as follows:
• Chapter 1, Introduction, describes the PC-DIO-24, lists what you need to get started,
describes software programming choices, optional equipment, and custom cables, and
explains how to unpack the PC-DIO-24.
• Chapter 2, Configuration and Installation, describes how to configure and install the
PC-DIO-24, including I/O connector signal descriptions, handshake timing diagrams, and
cabling instructions.
• Chapter 3, Theory of Operation, contains a functional overview of the PC-DIO-24 board and
explains the operation of each functional unit making up the PC-DIO-24.
• Chapter 4, Register-Level Programming, describes in detail the address and function of each
of the PC-DIO-24 control and status registers. This chapter also includes important
information related to register-level programming the PC-DIO-24.
• Appendix A, Specifications, lists the specifications for the PC-DIO-24 board.
• Appendix B, I/O Connector, describes the pinout and signal names for the I/O connector on
the PC-DIO-24.
• Appendix C, OKI 82C55A Data Sheet,contains the manufacturer data sheet for the
OKI 82C55A (OKI Semiconductor) CMOS programmable peripheral interface. This
interface is used on the PC-DIO-24 board.
• Appendix D, 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, symbols, and terms.

About This Manual
PC-DIO-24 User Manual xii © National Instruments Corporation
• The Index alphabetically lists the topics in this manual, including the page where you can
find each one.
Conventions Used in This Manual
The following conventions are used in this manual.
bold Bold text denotes menus, menu items, or dialog box buttons or options.
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.
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.
NI-DAQ NI-DAQ refers 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
unless otherwise noted.
SCXI SCXI stands for Signal Conditioning eXtensions for Instrumentation and
is a National Instruments product line designed to perform front-end signal
conditioning for National Instruments plug-in DAQ boards.
< > Angle brackets containing numbers separated by an ellipses represent a
range, signal, or port (for example, ACH<0..7> stands for ACH0 through
ACH7).
Abbreviations, acronyms, metric prefixes, mnemonics, and symbols are listed in the Glossary.
National Instruments Documentation
The PC-DIO-24 User Manual is one piece of the documentation set for your data acquisition
(DAQ) 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:
•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.

About This Manual
© National Instruments Corporation xiii PC-DIO-24 User Manual
• Your SCXI hardware user manuals—If you are using SCXI, read these manuals next for
detailed information about signal connections and module configuration. They also explain
in greater detail how the module works and contain application hints.
• Your DAQ hardware user manuals—These manuals have detailed information about the
DAQ hardware that plugs into or is connected to your computer. Use these manuals for
hardware installation and configuration instructions, specification information about your
DAQ hardware, and application hints.
• Software manuals—Examples of software manuals you may have are the LabVIEW and
LabWindows®/CVI manual sets and the NI-DAQ manuals (a 4.6.1 or earlier version of
NI-DAQ supports LabWindows for DOS). 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.
• SCXI chassis manuals—If you are using SCXI, read these manuals for maintenance
information on the chassis and installation instructions.
Related Documentation
The following documents contain information that you may find helpful as you read this manual:
• IBM Personal Computer AT Technical Reference manual
• IBM Personal Computer XT Technical Reference 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 D, Customer
Communication, at the end of this manual.

© National Instruments Corporation 1-1 PC-DIO-24 User Manual
Chapter 1
Introduction
This chapter describes the PC-DIO-24, lists what you need to get started, describes software
programming choices, optional equipment, and custom cables, and explains how to unpack the
PC-DIO-24.
About the PC-DIO-24
Thank you for purchasing the National Instruments PC-DIO-24. The PC-DIO-24 is a low cost,
24-bit parallel, digital I/O interface for the PC. An OKI 82C55A PPI controls the 24 bits of
digital I/O. The 82C55A is very flexible and powerful when interfacing with peripheral
equipment, can operate in either a unidirectional or bidirectional bus mode, and can generate
interrupt request outputs. The 82C55A can be programmed for almost any 8-bit or 16-bit digital
I/O application. All digital I/O is through a standard 50-pin male connector. The pin
assignments for this connector are compatible with standard 24-channel digital I/O applications.
The PC-DIO-24 can be used in a wide range of digital I/O applications. With the PC-DIO-24, a
PC can be interfaced to any of the following.
• Other computers
- Another PC with a National Instruments PC-DIO-24 or AT-DIO-32F
- IBM Personal System/2 with a National Instruments MC-DIO-24 or MC-DIO-32F
- Apple Macintosh II with a National Instruments NB-DIO-24 or NB-DIO-32F
- Any other computer with an 8-bit or 16-bit parallel interface
• Centronics-compatible printers and plotters
• Panel meters
• Instruments and test equipment with BCD readouts and/or controls
• Opto-isolated solid-state relays (SSRs) and I/O module mounting racks
Note: The PC-DIO-24 cannot sink sufficient current to drive the SSR-OAC-5 and
SSR-OAC-5A output modules. However, it can drive the SSR-ODC-5 output module
and all SSR input modules available from National Instruments.
If you need to drive a SSR-OAC-5 or SSR-OAC-5A, you can either use a non-inverting
digital buffer chip between the PC-DIO-24 and the SSR backplane, or you can use a
DIO-23F or MIO Series board with appropriate connections (e.g., SC-205X and
cables).

Introduction Chapter 1
PC-DIO-24 User Manual 1-2 © National Instruments Corporation
With the PC-DIO-24, the PC can serve as a digital I/O system controller for laboratory testing,
production testing, and industrial process monitoring and control.
Detailed specifications of the PC-DIO-24 are in Appendix A, Specifications.
What You Need to Get Started
To set up and use your PC-DIO-24, you will need the following:
PC-DIO-24 board
PC-DIO-24 User Manual
One of the following software packages and documentation:
NI-DAQ for PC compatibles
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. A 4.6.1 or earlier
version of NI-DAQ supports LabWindows for DOS.
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 PC-DIO-24 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
PC-DIO-24 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 easier than, and as flexible as, register-level
programming, and can save weeks of development time.
Optional Equipment
National Instruments offers a variety of products to use with your PC-DIO-24 board, including
cables, connector blocks, and other accessories, as follows:
• Cables and cable assemblies, shielded and ribbon
• Connector blocks, shielded and unshielded 50-pin screw terminals
• Signal conditioning eXtensions for Instrumentation (SCXI) modules and accessories for
isolating, amplifying, exciting, and multiplexing signals for relays and analog output. With
SCXI you can condition and acquire up to 3,072 channels.
• Low channel count signal conditioning modules, boards, and accessories, including
conditioning for strain gauges and RTDs, simultaneous sample and hole, and relays.
For more specific information about these products, refer to your National Instruments catalog or
call the office nearest you.
Custom Cables
National Instruments offers cables and accessories for you to prototype your application or to use
if you frequently change board interconnections.
If you want to develop your own cable, however, the following guidelines may be useful:
The PC-DIO-24 I/O connector is a 50-pin male ribbon-cable header. The manufacturer part
numbers used by National Instruments for this header are as follows:
• Electronic Products Division/3M (part number 3596-5002)
• T&B/Ansley Corporation (part number 609-5007)
The mating connector for the PC-DIO-24 is a 50-position, polarized, ribbon socket connector
with strain relief. National Instruments uses a polarized (keyed) connector to prevent inadvertent
upside-down connection to the PC-DIO-24. Recommended manufacturer part numbers for this
mating connector are as follows:

Chapter 1 Introduction
© National Instruments Corporation 1-5 PC-DIO-24 User Manual
• Electronic Products Division/3M (part number 3425-7650)
• T&B/Ansley Corporation (part number 609-5041CE)
The standard ribbon cable (50-conductor, 28 AWG, stranded) that can be used with these
connectors is as follows:
• Electronic Products Division/3M (part number 3365/50)
• T&B/Ansley Corporation (part number 171-50)
Recommended manufacturer part numbers for the 50-pin edge connector for connecting to a
module rack with an edge connector are as follows:
• Electronic Products Division/3M (part number 3415-0001)
• T&B Ansley Corporation (part number 609-5015M)
A polarizing key can be plugged into these edge connectors to prevent inadvertent upside-down
connection to the I/O module rack. The location of this key varies from rack to rack. Consult
the specification for the rack you intend to use for the location of any polarizing key. The
recommended manufacturer part numbers for this polarizing key are as follows:
• Electronic Products Division/3M (part number 3439-2)
• T&B Ansley Corporation (part number 609-0005)
If you plan to use the PC-DIO-24 for a communications application, you may need shielded
cables to meet FCC requirements. The PC-DIO-24 I/O bracket has been designed so that the
shield of the I/O cable can be grounded through the computer chassis when a mating connector
such as the following is used:
• AMP Special Industries (part number 2-746483-2)
Many varieties of shielded ribbon cable are available to work with the mating connector listed
previously. One type of shielded cable encloses a standard ribbon cable with a shielded jacket.
Recommended manufacturers and the appropriate part numbers for this type of cable are as
follows:
• Belden Electronic Wire and Cable (part number 9L28350)
• T&B/Ansley Corporation (part number 187-50)

Introduction Chapter 1
PC-DIO-24 User Manual 1-6 © National Instruments Corporation
Unpacking
Your PC-DIO-24 board is shipped in an antistatic package to prevent electrostatic damage to the
board. Electrostatic discharge can damage several components on the board. To avoid such
damage in handling the board, take the following precautions:
• Ground yourself via a grounding strap or by holding a grounded object.
• Touch the antistatic package to a metal part of your PC chassis before removing the board
from the package.
• Remove the board from the package and inspect the board for loose components or any other
sign of damage. Notify National Instruments if the board appears damaged in any way. Do
not install a damaged board into your computer.
•Never touch the exposed pins of connectors.

© National Instruments Corporation 2-1 PC-DIO-24 User Manual
Chapter 2
Configuration and Installation
This chapter describes how to configure and install the PC-DIO-24, including I/O connector
signal descriptions, handshake timing diagrams, and cabling instructions.
Board Configuration
The PC-DIO-24 contains one DIP switch and two jumpers to configure the base I/O address and
interrupts, respectively. The PC-DIO-24 also contains one fuse to protect the +5 V power
output. Figure 2-1 shows the location of jumper sets W1 and W2, DIP switch U2, and the
fuse F1.
The PC-DIO-24 is configured at the factory to a base I/O address of hex 210, to use interrupt
enable line PC4, and to use interrupt level 5. These settings (shown in Table 2-1) are suitable for
most systems. However, if your system has other hardware at this base I/O address, interrupt
enable line, or interrupt level, you need to change these settings on the PC-DIO-24 (as described
in the following pages) or on the other hardware. Record your settings in the PC-DIO-24
Hardware and Software Configuration Form in Appendix D, Customer Communication.
Table 2-1. PC-DIO-24 Factory-Set Jumper and Switch Settings
Base I/O Address Hex 210
(factory setting)
U2
A9 A8 A7 A6 A5 A4 A3 A2
1 2 3 4 5 6 7 8
(The black side indicates the side that
is pushed down.)
Interrupt Enable Line PC4
(factory setting) W1: Row PC4
Interrupt Level Interrupt level 5 selected
(factory setting) W2: IRQ5

Configuration and Installation Chapter 2
PC-DIO-24 User Manual 2-2 © National Instruments Corporation
4 3
21
NATIONAL
INSTRUMENTS


1U2
2W1
3F1
4W2
Figure 2-1. PC-DIO-24 Parts Locator Diagram
Base I/O Address Settings
The base I/O address for the PC-DIO-24 is determined by the switches at position U2 (see
Figure 2-1). The switches are set at the factory for the I/O address hex 210. With this default
setting, the PC-DIO-24 uses the I/O address space hex 210 through 213.
Note: Verify that this space is not already used by other equipment installed in your
computer. If any equipment in your computer uses this I/O address space, you must
change the base I/O address for the PC-DIO-24 or for the other device.
Each switch in U2 corresponds to one of the address lines A9 through A2. Thus, the range for
possible base I/O address settings is hex 000 through 3FC. Base I/O address values hex 000
through 0FF are reserved for system use. Base I/O values hex 100 through 3FF are available on
the I/O channel. A1 and A0 are used by the PC-DIO-24 to decode the onboard registers. On the

Chapter 2 Configuration and Installation
© National Instruments Corporation 2-3 PC-DIO-24 User Manual
U2 DIP switches, press the side marked OFF to select a binary value of 1 for the corresponding
address bit. Press the other side of the switch to select a binary value of 0 for the corresponding
address bit. Figure 2-2 shows two possible switch settings. The black side indicates the side that
is pushed down.
O
F
F
12345678
O
N
U2
A9 A8 A7 A6 A5 A4 A3 A2
A. Switches Set to Default Setting (Base I/OAddress Hex 210)
O
F
F
12345678
O
N
U2
A9 A8
A7
A6 A5 A4 A3 A2
B. Switches Set to Base I/OAddress Hex 278
Figure 2-2. Example Base I/O Address Switch Settings