Supervision is the function that allows the operator to have an immediate view of the process status and to control how the process evolves over time by analyzing the sequence of operating states.
The main task of the supervision is to realize the human-machine interface (HMI). To be effective, the HMI must provide the operator with a prompt and complete image of the whole process, highlighting the status, the evolution and the unexpected deviations (alarms).
For an effective HMI, the graphic representation is of great importance, since it translates information relevant to the process into a visual language of easy understanding for the operator.
For example, you can display the status of a pump through a graphic symbol with different colors, the change of the value of a pressure through a graphical trend, the occurrence of an alarm through a pop-up window.