Siemens SIMATIC ET 200iS Manual page 210

Digital Electronics Modules
13.4 Parameter Description
13.4.1 Pulse extension
Introduction
Pulse extension is a function for changing a digital input signal. A pulse at a digital
input is extended to at least the length set in the parameters. If the input pulse is
already longer than the selected length, it is not changed
Principle Behind Pulse Lengthening
The following figure illustrates with examples if and how input pulses are changed.
Process signal
Processed
input signal
Process signal
Processed
input signal
The second pulse, which occurs
during pulse lengthening, is
delayed until completion of pulse
lengthening.
Figure 13-4 Principle of Pulse Extension
13-14
Parameter for pulse lengthening = T
®
T for 0 1 edge
1
®
T for 1 0 edge
1
Pulse is shorter
than T and is lengthened
1
to T
1
1
Pulse is longer than T
1
and is not changed
Short pulses that occur
during pulse lengthening
are ignored.
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