Firstly, the operating status transmitted by the control unit must be checked. If there is a change, it must be reacted to. Further tasks are:

  • Status of the switching commands issued by the signals. The internal values must be synchronised and tracked. Is the traffic stream already green or still red?
  • Checking the inputs. The data from the physical inputs is transferred to the logical vs | plus inputs.
  • Tracking all internal values. 
  • Check that the current parameters are available. 
  • etc.