National Instruments DAQ X Series, Руководство пользователя

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Chapter 7 Counters
X Series User Manual 7-32 ni.com
Finite Pulse Train Generation
This f u nction generates a train of p u lses with programmable freq u ency and
d u ty cycle for a predetermined n u mber of p u lses. With X Series co u nters,
the primary co u nter generates the specified p u lse train and the embedded
co u nter co u nts the p u lses generated by the primary co u nter. When the
embedded co u nter reaches the specified tick co u nt, it generates a trigger
that stops the primary co u nter generation.
Figure 7-29. Finite Pulse Train Generation: Four Ticks Initial Delay, Four Pulses
In Legacy Mode, this co u nter operation req u ires two co u nters and does not
u se the embedded co u nter. For example, to generate fo u r p u lses on
Co u nter 0, Co u nter 0 generates the p u lse train, which is gated by the paired
second co u nter. The paired co u nter, Co u nter 1, generates a p u lse of desired
width.
Note Co u nter 0 is always paired with Co u nter 1. Co u nter 2 is always paired with
Co u nter 3.
The ro u ting is done internally. Fig u re 7-30 shows an example finite p u lse
train timing diagram.
Figure 7-30. Finite Pulse Train Timing in Legacy Mode
En ab le x
S o u rce
Ctr x
Co u nter Armed
Co u nter 1
(P a ired Co u nter)
Co u nter 0
Gener a tion
Complete
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