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Chapter 25
Easy Counter VIs
Generate Pulse Train
Configures the specified counter to generate a continuous pulse train on the counter's
OUT pin, or to generate a finite-length pulse train using the specified counter and an
adjacent counter. The signal has the prescribed frequency, duty cycle, and polarity. Each
cycle of the pulse train consist of a delay phase (phase 1) followed by a pulse phase
(phase 2).
This VI uses only the specified counter to generates a continuous pulse. For a
finite-length pulse, the VI also uses counter–1 to generate a minimum-delayed pulse to
gate counter. To generate another pulse train, execute the intermediate Counter Start VI
with the taskIDs supplied by this VI. To stop a continuous pulse train, execute the
intermediate Counter Stop VI or execute this counter again to generate one, short pulse.
You must externally wire counter–1’s OUT pin to counter's GATE pin for a finite-length
pulse train. You can optionally gate or trigger the start of the train with a signal on the
counter–1’s GATE pin.
Note:
A pulse train consists of a series of delayed pulses, where phase 1 or the
first phase of each pulse is the inactive state of the output (low for a high
pulse) and the phase 2 of the second phase is the pulse itself. Refer to the
following illustration of a high polarity pulse train.
Measure Frequency
Measures the frequency of a TTL signal on the specified counter’s SOURCE pin by
counting positive edges of the signal during a specified period of time. In addition to this
connection, you must wire the counter’s GATE pin to the OUT pin of counter–1. This VI
is useful for relatively high frequency signals, when many cycles of the signal occur
during the timing period. Use the Measure Pulse Width or Period VI for relatively low
frequency signals. Keep in mind that period(s) = 1/frequency (Hz).
© National Instruments Corporation
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LabVIEW Function and VI Reference Manual