National Instruments PC-DIO-24 - Manual (Page 34)

Register-Level Programming Chapter 4
PC-DIO-24 User Manual 4-4 © National Instruments Corporation
D2 D1 D0 D5 D4 D3 D7 D6
(high nibble)
1 = input
0 = output
Control Word
Flag
1 = mode set
00 = mode 0
01 = mode 1
1X = mode 2 Mode Selection
1 = input
0 = output Port A
Port C
(low nibble)
1 = input
0 = output
Port C
0 = mode 0
1 = mode 1 Mode Selection
Group A Group B
Port B
1 = input
0 = output
Flag
D2 D1 D0 X X D3 D7 X
0 = bit set/reset
1 = set
0 = reset
(000)
(001)
(010)
:
:
(111)
Control Word
Bit Select
Bit Set/Reset
a. Mode Set Word Format
b. Bit Set/Reset Word Format
Figure 4-1. Control-Word Formats
Single Bit Set/Reset Feature
Table 4-2 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.