Siemens SIMATIC ET 200SP Manual page 28

Reporting a chatter error
If a chatter error occurs, the current signal status is entered in the process image and the
value status of the signal is set to "invalid" (QI = 0). If "Chatter error" diagnostics is enabled,
"Chatter error" is also entered as diagnostic information, triggering an incoming diagnostics
interrupt.
You can evaluate and process the value status (QI) and the diagnostics information in the
user program.
Resetting a chatter error
If no further chattering of the input signal is detected within three monitoring windows, an
outgoing diagnostics interrupt is triggered. The status of the value of the current signal in the
process image is set to "valid".
Note
Active chatter monitoring is reset if there is an error in the input signal (value status QI =0 ).
Principle
The following figure gives you another graphic illustration of the principle of chatter
monitoring.
Figure 5-3
DI 8xNAMUR HF digital input module (6ES7131-6TF00-0CA0)
Manual, 02/2014, A5E03894478-01
The principle of chatter monitoring
Interrupts/diagnostics alarms
5.5 Chatter monitoring
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