Chatter Monitoring - Siemens SIMATIC ET 200SP Manual

Interrupts/diagnostics alarms

5.5 Chatter monitoring

Tip: Data records 0 to 7 and changeover sensor
Using the data records 1, 3, 5 and 7, you can configure a changeover sensor on an even
channel (normally closed contact channel).
The corresponding normally open contact channel can be configured with the data records 0,
2, 4 and 6.
An even changeover contact channel must be followed by an odd, deactivated channel.
Otherwise:
● you receive a parameter assignment error or
● the parameter assignment is rejected and the current parameter assignment retained.
Remedy: First, send data records 1, 3, 5 and 7 with deactivated, and then send data records
0, 2, 4 and 6 with changeover contact.
5.5 Chatter monitoring
Description
Chatter monitoring is a process control function for digital input signals. It detects and reports
signal changes that are unexpected in process engineering, for example when an input
signal fluctuates too often between "0" and "1". This period is known as the "monitoring
window". If signal characteristics like these occur, it is a sign that the sensors are faulty or
that there are instabilities from a process engineering viewpoint.
Activating chatter monitoring
You activate chatter monitoring by specifying a permitted number of input signal changes
between "0" and "1" within the monitoring window. The number 0 deactivates the chatter
monitoring function.
A chatter error detected by the chatter monitoring has a direct effect on the value status (QI).
Detecting a chatter error
Each input channel has a monitoring window that has been assigned parameters. The
monitoring window is started the first time the input signal changes. If the input signal
changes within the monitoring window more often than the configured number of signal
changes, this is recognized as a chatter error. If no chatter error is detected within the
monitoring window, the window is restarted at the next signal change.
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DI 8xNAMUR HF digital input module (6ES7131-6TF00-0CA0)
Manual, 02/2014, A5E03894478-01