Chapter 7
Counters
©
National Instruments
7-33
X Series User Manual
Retriggerable Pulse or Pulse Train Generation
The co
u
nter can o
u
tp
u
t a single p
u
lse or m
u
ltiple p
u
lses in response to each
p
u
lse on a hardware Start Trigger signal. The generated 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 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
initial delay can be applied to only the first trigger or to all triggers
u
sing
the CO.EnableInitalDelayOnRetrigger property. The defa
u
lt for a single
p
u
lse is Tr
u
e, while the defa
u
lt for finite p
u
lse trains is False.
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. For retriggered p
u
lse
generation, pa
u
se triggers are not allowed since the pa
u
se trigger also
u
ses
the gate inp
u
t.
Fig
u
re 7-31 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) with
CO.EnableInitalDelayOnRetrigger set to the defa
u
lt Tr
u
e.
Figure 7-31.
Retriggerable Single Pulse Generation with Initial Delay on Retrigger
S
OURCE
GATE
(
S
t
a
rt Trigger)
OUT
5
3
5
3
Co
u
nter
Lo
a
d V
a
l
u
e
s
4
3
2 1 0 2 1 0
4
3
2 1 0 2 1 0
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