Chapter 3
Signal Connections
3-8
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National Instruments Corporation
Digital I/O Signal Connections
Figure 3-5 illustrates signal connections for three typical digital I/O
applications.
Figure 3-5.
Digital I/O Connections
In Figure 3-5, port 0 is configured for digital output and port 1 is configured
for digital input.
Digital input applications include receiving TTL signals and sensing
external device states such as the switch in Figure 3-5. Digital output
applications include sending TTL signals and driving external devices
such as the LED shown in Figure 3-5.
Note
The VXI-AO-48XDC allows line-by-line control of digital I/O connections.
Refer to Appendix A,
, for a list of the digital I/O signal
ratings.
Power-up Condition
At power up, ports 0 through 3 of the digital I/O circuitry on the
VXI-AO-48XDC are configured as input ports.
Switch
DGND
+5 V
I/O Connector
TTL Signal
LED
R
+5 V
Port 0
Line<7..0>
Port 1
Line<7..0>
VXI-AO-48XDC