© National Instruments
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3-7
Figure 3-8.
Pulse Measurement
Create Channel
To make a Pulse measurement, first create a virtual channel. Use one of following three VIs or
functions depending on the type of data you want DAQmx to return:
•
DAQmx Create Channel (CI-Pulse Freq)
—For each measurement, return the frequency
and the duty cycle of the signal-to-measure.
•
DAQmx Create Channel (CI-Pulse Time)
—For each measurement, return the high and
low times of the pulse in seconds.
•
DAQmx Create Channel (CI-Pulse Ticks)
—For each measurement, return the high and
low times of the pulse in ticks of the counter timebase.
Channel Settings
By default, the counter:
•
measures the pulse on a default PFI terminal. Refer to Chapter 5,
•
begins measuring on a rising edge. That is, the counter measures the pulse high time first,
then the low time.
You can change these behaviors by configuring the following DAQmx Channel properties:
•
The signal-to-measure comes from an input terminal. To change the signal-to-measure,
select the appropriate property from the following list that corresponds to the type of
channel created, and then set this property to a different terminal.
–
CI.Pulse.Freq.Term
–
CI.Pulse.Time.Term
–
CI.Pulse.Ticks.Term
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