Appendix B
Register-Level Programming
©
National Instruments Corporation
B-13
DAQCard-DIO-24 User Manual
4
INTEA
Interrupt Enable Bit for Port A—Enables
interrupts from the 82C55A for port A.
Controlled by bit set/reset of PC4.
3
INTRA
Interrupt Request Status for
Port A—When INTEA is high and IBFA
is high, this bit is high, indicating that an
interrupt request is asserted.
2
INTEB
Interrupt Enable Bit for Port B—Enables
interrupts from the 82C55A for port B.
Controlled by bit set/reset of PC2.
1
IBFB
Input Buffer Full for Port B—High
indicates that data has been loaded into
the input latch for port B.
0
INTRB
Interrupt Request Status for Port B—
When INTEB is high and IBFB is high,
this bit is high, indicating that an
interrupt request is asserted.
At the digital I/O connector, port C has the following pin assignments
when in mode 1 input. Notice in Figure B-2 that the status of STBA*
and STBB* is not included in the port C status word.
Figure B-2.
Port C Pin Assignments in Mode 1 Input
PC7
PC6
PC5
PC4
PC3
PC2
PC1
PC0
I/O
I/O
IBFA
STBA*
INTRA
STBB*
IBFB
INTRB
Group A
Group B