Edge Detection - Siemens SIMATIC S7-200 Getting Started

3.3

Edge detection

In our example, we use the -|P|- function as follows:
Getting Started - Advanced
Training Documents, 09/2007, A5E01469795B
Pulse Operated Switch
The moment of transition of a
contact (input, output ...) from
"open" to "closed" or from "false"
to "true" is referred to as the
rising or positive edge.
Correspondingly, the transition
from "closed" to "open" or from
"true" to "false" is referred to as
the falling or negative edge.
The two Bit Logic functions -|P|-
and -|N|- can detect rising and
falling edges.
And this is what the
—|P|— function output
signal looks like.
3.3 Edge detection
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