Pulse Extension; Chatter Monitoring - Siemens SIMATIC ET 200SP Manual

4.2.4.3

Pulse extension

Function
Pulse extension is a function to change a digital input signal. A pulse on a digital input is
extended to at least the assigned length. If the input pulse is already longer than the
assigned length, the pulse is not changed.
The fail-safe electronic module only lengthens pulses with the value "0" because the basis of
the safety concept is that there is a safe state for all process variables. For digital F-I/O, this
is the value "0", which applies to sensors as well as to actuators.
With 1oo2 evaluation, the result of the evaluation of both sensors is used for the pulse
extension.
4.2.4.4

Chatter monitoring

Function
Chatter monitoring is a process control function for digital input signals. It detects and reports
unusual signal sequences in the process with 1oo1 evaluation, for example, an input signal
fluctuating between "0" and "1" too frequently. The occurrence of such signal characteristics
is an indication of faulty sensors or process control instability.
Recognizing unusual signal patterns
An assigned monitoring window is available for each input channel. The monitoring window
starts with the first signal change of the input signal. If the input signal changes within the
monitoring window at least as often as the assigned "Number of signal changes", a chatter
error is detected. If no chatter error is detected within the monitoring window, the next signal
change restarts the monitoring window.
If a chatter error is detected, a diagnostic is signaled. If the chatter error does not occur for
the monitoring window for three times the configured period, the diagnostic is reset.
Digital input module F-DI 8x24VDC HF (6ES7136-6BA00-0CA0)
Manual, 07/2013, A5E03858068-01
Parameters/address space
4.2 Explanation of parameters
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