Chapter 3
Signal Connections
©
National Instruments Corporation
3-7
Digital I/O Signal Connections
Pins 1 through 48 and pins 51 through 98 of the I/O connector are digital
I/O signal pins. Figure 3-5 depicts signal connections for three typical
digital I/O applications.
Figure 3-5. Digital I/O Connections
In Figure 3-5, PPI A, port A is configured for digital output, and PPI C,
port B is configured for digital input. Digital input applications include
receiving TTL signals and sensing external device states, such as the state
of 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.
* Complex switch circuitry is not shown in order to simplify the figure.
DAQPad-6507/6508
Switch *
I/O Connector
+5 V
+5 V
LED
TTL Signal
41
43
45
47
67
71
73
69
50, 100
+5 V
Front Switch
100 k
Ω
100 k
Ω
100 k
Ω
100 k
Ω
100 k
Ω
100 k
Ω
100 k
Ω
100 k
Ω
PPI C
Port B
CPB<7..4>
PPI A
Port A
APA<3..0>
GND
