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Appendix B
Register-Level Programming
©
National Instruments Corporation
B-9
DAQCard-DIO-24 User Manual
Single Bit Set/Reset Feature
Any of the eight bits of port C can be set or reset with one control word.
This feature generates status and control for port A and port B when
operating in mode 1 or mode 2.
Mode 0 Basic I/O
Mode 0 can be used for simple I/O functions for each of the three ports
with no handshaking. Each port can be assigned as an input or an output
port. The upper and lower nibbles of port C can be configured for
different directions. The 16 possible I/O configurations are shown in
Table B-3. Notice that bit 7 of the control word is set when
programming the mode of operation for each port
.
Table B-3.
Mode 0 I/O Configurations
Control Word Bit
Group A
Group B
Number
76543210
Port A
Port C
Port B
1
Port C
2
0
10000000
Output
Output
Output
Output
1
10000001
Output
Output
Output
Input
2
10000010
Output
Output
Input
Output
3
10000011
Output
Output
Input
Input
4
10001000
Output
Input
Output
Output
5
10001001
Output
Input
Output
Input
6
10001010
Output
Input
Input
Output
7
10001011
Output
Input
Input
Input
8
10010000
Input
Output
Output
Output
9
10010001
Input
Output
Output
Input
10
10010010
Input
Output
Input
Output
1
Upper nibble of port C
2
Lower nibble of port C