National Instruments NI 9403 - Manual (Page 8)

NI 9403 Operating Instructions and Specifications 8 ni.com
Refer to Figure 2 for an illustration of several types of digital
devices connected to the NI 9403.
Figure 2. Connecting Digital Devices to the NI 9403
TTL Signal
+5 V
+5 V
LED
DIO0 as Input
DIO1 as Input
COM
DIO2 as Output
NI 9403 Dev 3
Dev 2
Dev 1