Hardware zone control

This section relates to the status of the associated sequences i.e. whether they are all in the manual mode or in the automatic mode of the zone. A zone automatic output is also used to start all associated sequences that are in automatic mode when an automatic-start button for that zone is pressed.

Each hardware zone contains a continuously monitored zone (T.C.M.Z.). A continuously monitored zone is an area of the PLC software that contains logic which is continuously monitored. Emergency-stop buttons, circuit breakers, safety doors, etc. should be located in this area of the program.

The T.C.M.Z. contains faults that apply to more than one sequence to prevent these faults from appearing redundantly in every sequence.