Network Card User Manual
Table Of Contents
- PC-DIO-24 User Manual
- Contents
- About This Manual
- Chapter 1 Introduction
- Chapter 2 Configuration and Installation
- Chapter 3 Theory of Operation
- Chapter 4 Register-Level Programming
- Appendix A Specifications
- Appendix B I/O Connector
- Appendix C OKI 82C55A Data Sheet*
- Appendix D Customer Communication
- Glossary
- Index
- Figures
- Figure 1-1. The Relationship between the Programming Environment, NI-DAQ, and Your Hardware
- Figure 2-1. PC-DIO-24 Parts Locator Diagram
- Figure 2-2. Example Base I/O Address Switch Settings
- Figure 2-3. Jumper Settings–PC6, PC4, PC2, and N/C
- Figure 2-4. Interrupt Jumper Setting for IRQ5 (Factory Setting)
- Figure 2-5. Digital I/O Connector Pin Assignments
- Figure 3-1. PC-DIO-24 Block Diagram
- Figure 4-1. Control-Word Formats
- Figure B-1. PC-DIO-24 I/O Connector
- Tables
- Table 2-1. PC-DIO-24 Factory-Set Jumper and Switch Settings
- Table 2-2. Port C Signal Assignments
- Table 4-1. PC-DIO-24 Address Map
- Table 4-2. Port C Set/Reset Control Words
- Table 4-3. Mode 0 I/O Configurations
- Table 4-4. Interrupt Enable Signals for All Mode Combinations
- Table A-1. Maximum Average Transfer Rates for the PC-DIO-24
© National Instruments Corporation 4-1 PC-DIO-24 User Manual
Chapter 4
Register-Level Programming
This chapter 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.
The PC-DIO-24 is a parallel, digital I/O board designed around the OKI 82C55A integrated
circuit. The 82C55A is a general-purpose peripheral interface containing 24 programmable I/O
pins. These pins represent the three 8-bit I/O ports (A, B, and C) of the 82C55A. These ports
can be programmed as two groups of 12 signals or as three individual 8-bit ports. This chapter
includes register-level programming information for the PC-DIO-24, along with program examples
written in C.
Note: If you plan to use a programming software package such as LabWindows/CVI or
NI-DAQ with your PC-DIO-24 board, you need not read this chapter.
Introduction
The three 8-bit ports are divided into two groups—group A and group B (two groups of 12
signals). One 8-bit configuration (or control) word determines the mode of operation for each
group. The group A control bits configure port A<0..7> and the upper 4 bits (nibble) of
port C<4..7>. The group B control bits configure port B<0..7> and the lower nibble of
port C<0..3>. These configuration bits are defined later in this chapter.
82C55A Modes of Operation
The three basic modes of operation for the 82C55A are as follows:
• Mode 0 – Basic I/O
• Mode 1 – Strobed I/O
• Mode 2 – Bidirectional bus
The 82C55A also has a single bit set/reset feature for port C. The 8-bit control word also
programs this function. For additional information, refer to Appendix C, OKI 82C55A Data
Sheet.