Chapter 3
Signal Connections
3-4
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Figure 3-2 illustrates the 44-pin D-SUB connector on the NI 8255R.
Figure 3-2.
NI 8255R 44-Pin D-SUB Connector
Table 3-2 lists pin numbers, signal names, and signal descriptions for the
44-pin D-SUB connector on the NI 8255R and the 37-pin terminal block.
Table 3-2.
Signal Connections
44-Pin D-SUB
on NI 8255R
Pin Number
37-Pin
Terminal
Block
Number
Signal
Name
Primary
Function
Alternate
Function
1
1
TTL Input 0
Pulse generator
trigger input
Trigger Change
Detector,
General-purpose
input
2
3
C
Common-mode
signal of the
NI 8255R device
main power
—
3
4
TTL Output 0
Watchdog timer
output
General-purpose
output
4
5
TTL Output 1
Pulse generator
output
General-purpose
output
5
6
C
Common-mode
signal of the
NI 8255R device
main power
—
1
16
31
15
30
44