Messages signal special process events at the operator interface.
Fault messages signal errors in the process. They are triggered by the PLC.
For this, fault messages need to have a process connection allocated to them.
Operation messages are also triggered by the PLC.
They signal a particular status in the machine or plant.
They serve to equip the user with additional information on the current status of the processes.
System messages are triggered by the operator interface.
System messages describe the status of the operator interface and inform the user about input or communication errors.