Counter Input Applications; Counting Edges; Single Point (On-Demand) Edge Counting - National Instruments NI cRIO-905x Series User Manual

Counter Input Applications

The following sections list the various counter input applications available on the cRIO
controller:
•

Counting Edges

• Pulse-Width Measurement
• Pulse Measurement
• Semi-Period Measurement
• Frequency Measurement
• Period Measurement
• Position Measurement
• Two-Signal Edge-Separation Measurement
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
Direction of Counting
clock.
Refer to the following sections for more information about edge counting options:
•

Single Point (On-Demand) Edge Counting

• 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. The following figure
shows an example of single point edge counting.
Figure 51. 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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section. The counter values can be read on demand or with a sample
Counter Armed
SOURCE
Counter Value 0 1 2 3
Controlling the
4 5