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System Event Tasks

A system event task executes its assigned programs every time the system event occurs. The execution of the assigned programs is done by a callback mechanism. If the system event occurs, the assigned programs are automatically executed once in the context of the caller which can be a controller kernel task or a device-specific task or interrupt.

Note System event tasks are not monitored by the watchdog because they are not executed in the context of a user event task.

For information on the events available for PLCnext Technology controllers, please refer to the PLCnext Info Center and the respective controller manual.

Special case: Exception events

Although many different exceptions are possible in the runtime, they are all processed in the system event 'Exception'. Consequently, the mere fact that the exception task was executed does not allow any conclusions to be drawn about the cause of the exception error. Use the GET_EXCEPTION_INFOS function block to read information on the exception from the runtime.