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Appendix B
Register-Level Programming
©
National Instruments Corporation
B-3
DAQCard-DIO-24 User Manual
Figure B-1.
Control-Word Formats
Single Bit Set/Reset Feature
Table B-2 shows the control words for setting or resetting each bit in
port C. Notice that bit 7 of the control word is cleared when
programming the set/reset option for the bits of port C. In this table n
represents the bit to be set or reset.
D0
D1
D2
D3
D4
D5
D6
D7
Group A
Group B
D0
D1
D2
D3
X
X
X
D7
a. Mode Set Word Format
b. Bit Set/Reset Word Format
Control-Word Flag
1 = mode set
Port A
1 = input
0 = output
Port C
(high nibble)
1 = input
0 = output
Port C
(low nibble)
1 = input
0 = output
Port B
1 = input
0 = output
Mode Selection
0 = mode 0
1 = mode 1
Bit Set/Reset
1 = set
0 = reset
Bit Select
(000)
(001)
(010)
.
.
.
.
(111)
Control-Word Flag
0 = bit set/reset
Mode Selection
00 = mode 0
01 = mode 1
1X = mode 2