©
National Instruments Corp.
11
NI 9476 Operating Instructions and Specifications
I/O Protection
The NI 9476 is protected against overc
u
rrent, inr
u
sh, and
short-circ
u
it conditions in accordance with IEC 1131-2.
Understanding Protected Devices
Each channel on the NI 9476 has circ
u
itry that protects it from
voltage and c
u
rrent s
u
rges res
u
lting from short circ
u
its.
Caution
The NI 9476 can be damaged
u
nder overvoltage
and reverse bias voltage conditions. Check the voltage
specifications for all devices that yo
u
connect to the
NI 9476.
Excessive c
u
rrent thro
u
gh a DO pin ca
u
ses the channel to go into
an overc
u
rrent state. In an overc
u
rrent state, the channel cycles off
and on
u
ntil the short circ
u
it is removed or the c
u
rrent ret
u
rns to an
acceptably low level. Refer the
section for typical
trip c
u
rrents.
Each channel has a stat
u
s line that indicates in software whether the
channel is in an overc
u
rrent state. Refer to the software help for
information abo
u
t reading o
u
tp
u
t stat
u
s.