Single Semi-Period Measurement; Implicit Buffered Semi-Period Measurement; Frequency Measurement - National Instruments X Series User Manual

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 measurement, on each edge of the Gate signal, the counter
stores the count in the FIFO. A DMA controller transfers the stored values to host memory.
The counter begins counting when it is armed. The arm usually occurs between edges on the
Gate input. You can select whether to read the first active low or active high semi period using
the CI.SemiPeriod.StartingEdge property in NI-DAQmx.
Figure 7-11 shows an example of an implicit buffered semi-period measurement.
Figure 7-11. Implicit Buffered Semi-Period Measurement
Counter Value
For information about connecting counter signals, refer to the
section.

Frequency Measurement

You can use the counters to measure frequency in several different ways. Refer to the following
sections for information about X Series frequency measurement options:
• Low Frequency with One Counter
• High Frequency with Two Counters
• Large Range of Frequencies with Two Counters
• Sample Clocked Buffered Frequency Measurement
• Hardware-Timed Single Point Frequency Measurement
Counter Starting
Armed Edge
Gate
Source
0
Buffer
1 2 3 1
3
3 1
Default Counter/Timer Pins
X Series User Manual
1 2 1
3
3
2
1
1
2
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