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National Instruments Corporation
21
NI cDAQ-9172 User Guide and Specifications
triggers can come from three separate modules if desired. To find your
module triggering options, refer to the documentation included with your
C Series I/O modules. For more information about using digital modules
for triggering, refer to the
section.
AI Start Trigger Signal
Use the AI Start Trigger (ai/StartTrigger) signal to begin a measurement
acquisition. A measurement acquisition consists of one or more samples. If
you do not use triggers, begin a measurement with a software command.
Once the acquisition begins, configure the acquisition to stop in one of the
following ways:
•
When a certain number of points is sampled (in finite mode)
•
After a hardware reference trigger (in finite mode)
•
With a software command (in continuous mode)
An acquisition that uses a start trigger (but not a reference trigger) is
sometimes referred to as a posttriggered acquisition. That is, samples are
measured only after the trigger.
When you are using an internal sample clock, you can specify a delay from
the start trigger to the first sample.
Using a Digital Source
To use ai/StartTrigger with a digital source, specify a source and an edge.
Use the following signals as the source:
•
Any PFI terminal.
•
Counter
n
Internal Output
The source also can be one of several other internal signals on your
NI cDAQ-9172 chassis. Refer to the
Device Routing in MAX
topic in the
NI-DAQmx Help
or the
LabVIEW Help
in version 8.0 or later for more
information.
The
NI-DAQmx Help
is available after installation from
Start»
All Programs»National Instruments»NI-DAQ»NI-DAQmx Help
.
To view the
LabVIEW Help,
in version 8.0 or later,
select
Help»
Search the LabVIEW Help
in LabVIEW. Alternately, to download
the
LabVIEW Help
, go to
ni.com/manual
s
.
You also can specify whether the measurement acquisition begins on the
rising edge or falling edge of ai/StartTrigger.
Summary of Contents for NI 9203
Page 1: ...NI 9203...
