© National Instruments
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11-3
AO External Reference input, as described in the
section of Chapter 5,
Analog Input Channels
Refer to the
Analog Input Channels on MIO X Series Devices
Simultaneous MIO X Series Devices
section, depending on your device.
Analog Input Channels on MIO X Series Devices
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
could also 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 Input Channels on Simultaneous MIO X Series Devices
With Simultaneous MIO X Series devices, every AI channel drives its own NI-PGIA. The
NI-PGIA amplifies the signal as determined by 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.
Since channels are not multiplexed, there are no restrictions on the analog input channel list
order or number of channels with reference and pause triggers. However, the analog input
channels must be in the scan 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
•
Digital input behavior
•
Digital output behavior
•
Counter behavior
Summary of Contents for DAQ X NI 634 Series
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