1. Towards technological realization

GRAFCET (step-transition control graph) is a graphical tool for representing the specifications of a sequential automation system. It is both easy to use and formally rigorous.

It is based on the notions of stages, to which actions are associated, and transitions, to which receptivities are associated. It describes the orders issued by the control part to the operative part, highlighting the actions generated and the events that trigger them. This representation is closely linked to the notion of process evolution.