National Instruments PC-DIO-24, User Manual

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Chapter 4 Register-Level Programming
© National Instruments Corporation 4-5 PC-DIO-24 User Manual
Table 4-2. Port C Set/Reset Control Words
Number Bit Set Bit Reset Bit Set or
Control Word Control Word Reset in Port C
0 0xxx0001 0xxx0000 xxxxxxxn
1 0xxx0011 0xxx0010 xxxxxxnx
2 0xxx0101 0xxx0100 xxxxxnxx
3 0xxx0111 0xxx0110 xxxxnxxx
4 0xxx1001 0xxx1000 xxxnxxxx
5 0xxx1011 0xxx1010 xxnxxxxx
6 0xxx1101 0xxx1100 xnxxxxxx
7 0xxx1111 0xxx1110 nxxxxxxx
Programming Considerations
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 16 possible I/O configurations are
shown in Table 4-3. Notice that bit 7 of the control word is set when programming the mode of
operation for each port.