National Instruments DAQ X Series, Руководство пользователя

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Chapter 7 Counters
X Series User Manual 7-10 ni.com
Implicit Buffered Pulse Measurement
In an implicit b u ffered p u lse meas u rement, on each edge of the Gate signal,
the co u nter stores the co u nt in the FIFO. A DMA controller transfers the
stored val u es to host memory.
The co u nter begins co u nting when it is armed. The arm u s u ally occ u rs
between edges on the Gate inp u t b u t the co u nting does not start u ntil the
desired edge. Yo u can select whether to read the high p u lse or low p u lse
first u sing the StartingEdge property in NI-DAQmx.
Fig u re 7-9 shows an example of an implicit b u ffered p u lse meas u rement.
Figure 7-9. Implicit Buffered Pulse Measurement
Sample Clocked Buffered Pulse Measurement
A sample clocked b u ffered p u lse meas u rement is similar to single p u lse
meas u rement, b u t a b u ffered p u lse meas u rement takes meas u rements over
m u ltiple p u lses correlated to a sample clock.
The co u nter performs a p u lse meas u rement on the Gate. On each sample
clock edge, the co u nter stores the high and low ticks in the FIFO of the last
p u lse to complete. A DMA controller transfers the stored val u es to host
memory.
G a te
S o u rce
H L
4 2
H L
4 2
4 4
6 2
2 2
H L
4 2
4 4
6 2
H L
4 2
4 4
B u ffer
Co u nter Armed
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