182 Rockwell Automation Publication 1769-UM022C-EN-P - June 2018
Chapter 12 Monitor Status and Handle Faults
When the safety task encounters a nonrecoverable safety fault that is cleared
programmatically in the Controller Fault Handler, the standard application
continues to execute.
If a safety task signature exists, you only need to clear the fault to enable the
safety task to run. If no safety task signature exists, the safety task cannot run
again until the entire application is downloaded again.
Recoverable Faults in the Safety Application
If a recoverable fault occurs in the safety application, the system may or may
not halt the execution of the safety task, depending upon whether or not the
fault is handled by the Program Fault Handler in the safety application.
When a recoverable fault is cleared programmatically, the safety task is allowed
to continue without interruption.
When a recoverable fault in the safety application is not cleared programmatically,
a Type 14, Code 2 recoverable safety fault occurs. The safety program execution
is stopped, and safety protocol connections are closed and reopened to
re-initialize them. Safety outputs are placed in the safe state and the producer of
safety-consumed tags commands the consumers to also place them in a safe state.
Recoverable faults let you edit the standard and safety application as required
to correct the cause of the fault. However, if a safety task signature exists or the
controller is safety-locked, you must first unlock the controller and delete the
safety task signature before you can edit the safety application.
View Faults
The Recent Faults dialog box on the Major Faults tab of the Controller
Properties dialog box contains two sub-tabs, one for standard faults and one for
safety faults.
ATTENTION:
Overriding the safety fault does not clear it! If you override the
safety fault, it is your responsibility to prove that doing so maintains safe
operation.
You must provide proof to your certifying agency that allowing a portion of the
system to continue to operate maintains safe operation.
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