Chapter 7
Counters
X Series User Manual
7-4
ni.com
Refer to the following sections for more information abo
u
t X Series edge
co
u
nting options:
•
Single Point (On-Demand) Edge Counting
•
Buffered (Sample Clock) Edge Counting
Single Point (On-Demand) Edge Counting
With single point (on-demand) edge co
u
nting, the co
u
nter co
u
nts the
n
u
mber of edges on the So
u
rce inp
u
t after the co
u
nter is armed. On-demand
refers to the fact that software can read the co
u
nter contents at any time
witho
u
t dist
u
rbing the co
u
nting process. Fig
u
re 7-2 shows an example of
single point edge co
u
nting.
Figure 7-2.
Single Point (On-Demand) Edge Counting
Yo
u
also can
u
se a pa
u
se trigger to pa
u
se (or gate) the co
u
nter. When the
pa
u
se trigger is active, the co
u
nter ignores edges on its So
u
rce inp
u
t. When
the pa
u
se trigger is inactive, the co
u
nter co
u
nts edges normally.
Yo
u
can ro
u
te the pa
u
se trigger to the Gate inp
u
t of the co
u
nter. Yo
u
can
config
u
re the co
u
nter to pa
u
se co
u
nting when the pa
u
se trigger is high or
when it is low. Fig
u
re 7-3 shows an example of on-demand edge co
u
nting
with a pa
u
se trigger.
Figure 7-3.
Single Point (On-Demand) Edge Counting with Pause Trigger
Co
u
nter Armed
S
OURCE
Co
u
nter V
a
l
u
e
1
0 5
4
3
2
Co
u
nter Armed
S
OURCE
P
aus
e Trigger
(P
aus
e When Low)
Co
u
nter V
a
l
u
e
1
0 0
5
4
3
2
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