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Chapter 8
Counters
©
National Instruments Corporation
8-23
Yo
u
can ro
u
te the Start Trigger signal to the Gate inp
u
t of the co
u
nter. Yo
u
can specify a delay from the Start Trigger to the beginning of each p
u
lse.
Yo
u
also can specify the p
u
lse width. The delay and p
u
lse width are
meas
u
red in terms of a n
u
mber of active edges of the So
u
rce inp
u
t.
The co
u
nter ignores the Gate inp
u
t while a p
u
lse generation is in progress.
After the p
u
lse generation is finished, the co
u
nter waits for another Start
Trigger signal to begin another p
u
lse generation.
Fig
u
re 8-24 shows a generation of two p
u
lses with a p
u
lse delay of five and
a p
u
lse width of three (
u
sing the rising edge of So
u
rce).
Figure 8-24.
Retriggerable Single Pulse Generation
For information abo
u
t connecting co
u
nter signals, refer to the
section.
Pulse Train Generation
Continuous Pulse Train Generation
This f
u
nction generates a train of p
u
lses with programmable freq
u
ency and
d
u
ty cycle. The p
u
lses appear on the Co
u
nter
n
Internal O
u
tp
u
t signal of the
co
u
nter.
Yo
u
can specify a delay from when the co
u
nter is armed to the beginning
of the p
u
lse train. The delay is meas
u
red in terms of a n
u
mber of active
edges of the So
u
rce inp
u
t.
Yo
u
specify the high and low p
u
lse widths of the o
u
tp
u
t signal. The p
u
lse
widths are also meas
u
red in terms of a n
u
mber of active edges of the So
u
rce
inp
u
t. Yo
u
also can specify the active edge of the So
u
rce inp
u
t (rising or
falling).
The co
u
nter can begin the p
u
lse train generation as soon as the co
u
nter is
armed, or in response to a hardware start trigger. Yo
u
can ro
u
te the Start
Trigger to the Gate inp
u
t of the co
u
nter.
S
OURCE
GATE
(
S
t
a
rt Trigger)
OUT