Minor faults should be reported to the process operator either by updating a bit for the HMI or by illuminating a light on a panel faceplate. Major faults, however, should be trapped and automatically recovered where possible.
Some major faults cannot be recovered, which further divides major faults into two categories:
- Major recoverable faults
- Major unrecoverable faults
Logix allows the user to create a fault routine, which can trap a fault and attempt to recover and continue running the process where possible. When a Logix controller encounters a major fault, it executes the program assigned to the controller fault handler.
It is recommended best practice to at least log all the faults that occur in the controller before programmatically clearing them. As discussed earlier, faults play an important role in troubleshooting problems with a process and should never be ignored. If a fault is...
