Buffered Pulse-Width Measurement - National Instruments NI 6221 User Manual

GATE
SOURCE
Counter Value
Buffer
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Figure 7-5 shows an example of a single pulse-width measurement.
GATE
SOURCE
Counter Value
HW Save Register
Figure 7-5. Single Pulse-Width Measurement

Buffered Pulse-Width Measurement

Buffered pulse-width measurement is similar to single pulse-width
measurement, but buffered pulse-width measurement takes measurements
over multiple pulses.
The counter counts the number of edges on the Source input while the Gate
input remains active. On each trailing edge of the Gate signal, the counter
stores the count in a hardware save register. A DMA controller transfers the
stored values to host memory.
Figure 7-6 shows an example of a buffered pulse-width measurement.
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Figure 7-6. Buffered Pulse-Width Measurement
Note that if you are using an external signal as the Source, at least one
Source pulse should occur between each active edge of the Gate signal.
This condition ensures that correct values are returned by the counter. If this
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Chapter 7
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M Series User Manual
Counters