©
National Instruments Corp.
7
NI 9401 Operating Instructions and Specifications
Each channel has a DIO pin to which yo
u
can connect a digital
inp
u
t or o
u
tp
u
t device. The eight DIO channels are internally
referenced to COM, so yo
u
can
u
se any of the nine COM lines as
a reference for the external signal.
The DIO channels are gro
u
ped in two ports, one containing
channels 0, 1, 2, and 3, and one containing channels 4, 5, 6, and 7.
Yo
u
can independently config
u
re each digital port in software for
inp
u
t or o
u
tp
u
t. Note that all fo
u
r channels in the port m
u
st share
the same line direction. Refer to the software help for information
abo
u
t config
u
ring ports on the NI 9401.
Each channel also has a p
u
ll-down resistor and incl
u
des
overvoltage, overc
u
rrent, and short-circ
u
it protection. Refer to the
section for more information abo
u
t inp
u
t thresholds
and overvoltage protection. Refer to the
section for more information abo
u
t overc
u
rrent protection.
