NI C Series - Pulse;Duty Cycle Measurement

Figure 10. Count Edges Pause Trigger
Counter Armed
0 1 2 3 4 5 6
Signal to Measure
Counter Value
Pause Trigger Source
Trigger Settings
Counter Arm—You can control when the counter starts counting through the counter
arm control. The counter waits for the active edge on the signal-to-measure aer it
is armed, and counts on every active edge on the signal-to-measure. Refer to your
soware documentation for more information on arming the counter.
Pulse/Duty Cycle Measurement
You can take pulse or duty cycle measurements with the NI-9361 on CompactRIO
systems only.
The counter measures the high and low durations of a pulse on a signal. Using the
measured values, you can calculate the duty cycle of the signal. The NI-9361 returns
the current measurement values when the counter is read. The measurement values
consist of the high and low times of the pulse in the number of ticks of the 100 MHz
counter timebase.
You can calculate the signal period using the following equation:
Signal Period
= T
pulsehigh
+ T
pulselow
where
■
T
pulsehigh
is the pulse high time
■
T
pulselow
is the pulse low time
You can calculate the duty cycle using the following equation:
Duty Cycle =
T
pulsehigh
Signal Period
The following figure shows an example of pulse measurement.
© National Instruments
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NI-9361 Getting Started