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5-3
Counter Input Applications
The following sections list the various counter input applications available on the cDAQ chassis:
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Counting Edges
In edge counting applications, the counter counts edges on its Source after the counter is armed.
You can configure the counter to count rising or falling edges on its Source input. You also can
control the direction of counting (up or down), as described in the
section. The counter values can be read on demand or with a sample clock.
Refer to the following sections for more information about edge counting options:
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Single Point (On-Demand) Edge Counting
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Buffered (Sample Clock) Edge Counting
Single Point (On-Demand) Edge Counting
With single point (on-demand) edge counting, the counter counts the number of edges on the
Source input after the counter is armed. On-demand refers to the fact that software can read the
counter contents at any time without disturbing the counting process. Figure 5-2 shows an
example of single point edge counting.
Figure 5-2.
Single Point (On-Demand) Edge Counting
You also can use a pause trigger to pause (or gate) the counter. When the pause trigger is active,
the counter ignores edges on its Source input. When the pause trigger is inactive, the counter
counts edges normally.
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