Figure 58. Sample Clocked Buffered Pulse Measurement
Counter
Armed
Gate
Source
H L
2 2
H L
2 2
3 3
Sample
Clock
S1
S2
Buffer
2
2
3
3
Note
If a pulse does not occur between sample clocks, an overrun error occurs.
For information about connecting counter signals, refer to the
section.
Semi-Period Measurement
In semi-period measurements, the counter measures a semi-period on its Gate input signal
after the counter is armed. A semi-period is the time between any two consecutive edges on
the Gate input.
You can route an internal or external periodic clock signal (with a known period) to the Source
input of the counter. The counter counts the number of rising (or falling) edges occurring on
the Source input between two edges of the Gate signal.
You can calculate the semi-period of the Gate input by multiplying the period of the Source
signal by the number of edges returned by the counter.
Refer to the following sections for more information about semi-period measurement options:
•
Single Semi-Period Measurement
•
Implicit Buffered Semi-Period Measurement
Pulse versus Semi-Period Measurements
section for information about the
differences between semi-period measurement and pulse measurement.
Single Semi-Period Measurement
Single semi-period measurement is equivalent to single pulse-width measurement.
Implicit Buffered Semi-Period Measurement
In implicit buffered semi-period measurements, on each edge of the Gate signal, the counter
stores the count in the FIFO. The sampled values will be transferred to host memory using a
high-speed data stream.
cRIO-904x User Manual
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© National Instruments
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