National Instruments DIO 6533 - Manual (Page 53)

Chapter 4 Signal Connections
DIO 6533 User Manual 4-10 © National Instruments Corporation
Unstrobed I/O
For low-speed, unstrobed operation, you can configure each individual
pin for input, standard output, or wired-OR output.
Figure 4-3 shows
DIOA<0..3> configured for input, DIOA<4..7> configured for standard
output, and DIOB<0..3> configured for wired-OR output. Unstrobed
input applications include sensing external device states, such as the
state of the switch shown in the figure, and receiving low-speed TTL
signals. Unstrobed output applications include driving external controls
and indicators such as the LED shown in
Figure 4-3 , and sending
low-speed TTL signals.