Chapter 11
Triggering
11-2
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You also can program your DAQ device to perform an action in response to
a trigger from a digital source. The action can affect the following:
•
Analog input acquisition
•
Analog output generation
•
Counter behavior
•
Digital waveform acquisition and generation
Triggering with an Analog Source
Some M Series devices can generate a trigger on an analog signal. To find
your device triggering options, refer to the specifications document for
your device.
Figure 11-2 shows the analog trigger circuit.
Figure 11-2.
Analog Trigger Circuit
You must specify a source and an analog trigger type. The source can be
either an APFI <0..1> terminal or an analog input channel.
APFI <0..1> Terminals
When you use either APFI <0..1> terminal as an analog trigger, you should
drive the terminal with a low-impedance signal source (less than 1 k
Ω
source impedance). If APFI <0..1> are left unconnected, they are
susceptible to crosstalk from adjacent terminals, which can cause false
triggering. Note that the APFI <0..1> terminals also can be used for other
functions such as the AO External Reference input, as described in the
Offset and AO Reference Selection
section of Chapter 5,
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