Contribution of the Grafcet model to synchrony in discrete events systems modelling

Discrete events theory is the base of automated manufacturing systems modelling. Determinism of the implementation is a main constraint for the control of these systems. With regards to the asynchronous models, such as Petri nets, which do not ensure such a requirement, the synchronous models and languages are more suitable to systems control. This paper is focused on one of them - Grafcet, which is an international standard, widely used in industrial applications, and shows its gradual evolution from synchrony to strong synchrony hypothesis. We propose an algebraic modelling of the Grafcet that formalizes this evolution. This approach is discussed with regards to the strong synchrony of the synchronous languages