Chapter 11
Triggering
X Series User Manual
11-4
ni.com
Analog Input Channels on MIO X Series Devices
Select any analog inp
u
t channel to drive the NI-PGIA. The NI-PGIA
amplifies the signal as determined by the inp
u
t gro
u
nd-reference setting
and the inp
u
t range. The o
u
tp
u
t of the NI-PGIA then drives the analog
trigger detection circ
u
it. By
u
sing the NI-PGIA, yo
u
can trigger on very
small voltage changes in the inp
u
t signal.
When the DAQ device is waiting for an analog trigger with a AI channel as
the so
u
rce, the AI m
u
xes sho
u
ld not ro
u
te different AI channels to the
NI-PGIA. If a different channel is ro
u
ted to the NI-PGIA, the trigger
condition on the desired channel co
u
ld be missed. The other channels also
co
u
ld generate false triggers.
This behavior places some restrictions on
u
sing AI channels as trigger
so
u
rces. When yo
u
u
se an analog start trigger, the trigger channel m
u
st be
the first channel in the channel list. When yo
u
u
se an analog reference or
pa
u
se trigger, and the analog channel is the so
u
rce of the trigger, there can
be only one channel in the channel list.
Analog Input Channels on Simultaneous MIO
X Series Devices
With Sim
u
ltaneo
u
s MIO X Series devices, every AI channel drives its own
NI-PGIA. The NI-PGIA amplifies the signal as determined by the inp
u
t
range. The o
u
tp
u
t of the NI-PGIA then drives the analog trigger detection
circ
u
it. By
u
sing the NI-PGIA, yo
u
can trigger on very small voltage
changes in the inp
u
t signal.
Since channels are not m
u
ltiplexed, there are no restrictions on the analog
inp
u
t channel list order or n
u
mber of channels with reference and pa
u
se
triggers. However, the analog inp
u
t channels m
u
st be in the scan list.
Analog Trigger Actions
The o
u
tp
u
t of the analog trigger detection circ
u
it is the Analog Comparison
Event signal. Yo
u
can program yo
u
r DAQ device to perform an action in
response to the Analog Comparison Event signal. The action can affect the
following:
•
Analog inp
u
t acq
u
isition
•
Analog o
u
tp
u
t generation
•
Digital inp
u
t behavior
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