National Instruments 6368, Руководство пользователя

Страница: 146 / 278

© National Instruments
|
7-11
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
For information about connecting counter signals, refer to the Default Counter/Timer Pins
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
1
2
3
1
3
3
S o u rce
G a te
Co u nter V a l u e
B u ffer
1 3
2
2 1 1
1 3
1 2 0
Co u nter
Armed
S t a rting
Edge