Corrected from:
c300 controller V3.14
3241 C controller V3.14
p300 panel controller V3.14
p500 panel controller V3.14
Response of the new version:
If the controller is switched off after an exception has occurred, the values of the RETAIN variables will remain saved fail-safe.
What happens?
After restarting the controller, the RETAIN variables are reset to their default values.
When does this behaviour occur?
The behaviour occurs if PLC processing is stopped due to an exception (e.g. task overflow = watchdog exception) and the controller is switched off after this. When restarting the controller, all RETAIN variables are reset to their default values.
Which products are affected?
c300 controller from V3.12
3241 C controller from V3.12
p300 panel controller from V3.12
p500 panel controller from V3.12
Short-term measures:
Do not switch off the controller if an exception has occurred, but carry out a 'Reset warm' (PLC Designer menu command Online>Reset warm) to quit the exception state.
Evaluation/recommendations:
Exceptions may occur during the test and commissioning phase of the machine. Due to this function restriction, variables that are safe against mains failure (RETAIN variables) do not retain their value after mains switching. In the production process of the machine there should not occur any exceptions.
