PLC-AuxTask

The PLC-AuxTask is used for communication between the PLC editors and the PLC runtime modules. This includes the download and Online Change of PLC control code as well as debugging (monitoring of values, setting of breakpoints, etc.). In addition, the PLC-AuxTask also processes the ADS messages that are sent to the runtime system independently of the development environment (TcXaeShell) (e.g. from an HMI).

The PLC-AuxTask is not a cyclic task and you should set its priority lower than this. This ensures that the cyclic tasks can interrupt the PLC-AuxTask. In the event of an online change, the new code is transferred to the target system via the PLC-AuxTask and the symbols are generated accordingly, etc. Only the “critical phase” of an online change, in which the code to be executed is exchanged, is protected in such a way that this process cannot be interrupted by the cyclical tasks.

If several PLC runtime modules use the same PLC tasks, they can influence each other through an online change.