National Instruments PCI-6281, User Manual

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M Series User Manual
When the reference trigger occurs, the DAQ device continues to write samples to the buffer until
the buffer contains the number of posttrigger samples desired. Figure 4-23 shows the final
buffer.
Figure 4-23.
Reference Trigger Final Buffer
Using a Digital Source
To use AI Reference Trigger with a digital source, specify a source and an edge. The source can
be any of the following signals:
• PFI <0..15>
• RTSI <0..7>
• PXI_STAR
The source also can be one of several internal signals on your DAQ device. Refer to
Device
Routing in MAX
in the
NI-DAQmx Help
or the
LabVIEW Help
for more information.
You also can specify whether the measurement acquisition stops on the rising edge or falling
edge of AI Reference Trigger.
Using an Analog Source
When you use an analog trigger source, the acquisition stops on the first rising edge of the
Analog Comparison Event signal.
Routing AI Reference Trigger Signal to an Output Terminal
You can route AI Reference Trigger out to any PFI <0..15> or RTSI <0..7> terminal.
All PFI terminals are configured as inputs by default.
AI Pause Trigger Signal
Use the AI Pause Trigger (ai/PauseTrigger) signal to pause and resume a measurement
acquisition. The internal sample clock pauses while the external trigger signal is active and
resumes when the signal is inactive. You can program the active level of the pause trigger to be
high or low.
Reference Trigger
Pretrigger Sa mple s
Complete B u ffer
Po s ttrigger Sa mple s