Chapter 11 Triggering
© National Instruments Corporation 11-3 M Series User Manual
Analog Input Channels
Select any analog input channel to drive the NI-PGIA. The NI-PGIA
amplifies the signal as determined by the input ground-reference setting
and the input range. The output of the NI-PGIA then drives the analog
trigger detection circuit. By using the NI-PGIA, you can trigger on very
small voltage changes in the input signal.
When the DAQ device is waiting for an analog trigger with a AI channel as
the source, the AI muxes should not route different AI channels to the
NI-PGIA. If a different channel is routed to the NI-PGIA, the trigger
condition on the desired channel could be missed. The other channels also
could generate false triggers.
This behavior places some restrictions on using AI channels as trigger
sources. When you use an analog start trigger, the trigger channel must be
the first channel in the channel list. When you use an analog reference or
pause trigger, and the analog channel is the source of the trigger, there can
be only one channel in the channel list.
Analog Trigger Actions
The output of the analog trigger detection circuit is the Analog Comparison
Event signal. You can program your DAQ device to perform an action in
response to the Analog Comparison Event signal. The action can affect the
following:
• Analog input acquisition
• Analog output generation
• Counter behavior
Routing Analog Comparison Event to an Output Terminal
You can route Analog Comparison Event out to any PFI <0..15> or
RTSI <0..7> terminal.
Analog Trigger Types
Configure the analog trigger circuitry to different triggering
modes—analog edge triggering, analog edge triggering with hysteresis,
or analog window triggering.
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