Defining the Semantics of Languages for Programmable Controllers with Synchronous Processes

Real-time systems are systems which interact permanently with their environment by receiving external information and producing output commands on it. They are commonly met in factories for the control of industrial processes. In this case, they are often implemented with Programmable Controllers (PC). The GRAFCET language, which is derived from Petri-Nets, is often used for programming such PC. Unfortunately, it is not based on a single semantics, which complicates program veriication, program exchange and program simulation. This paper shows how to express its semantics with synchronous processes, implemented by the synchronous language SIGNAL and investigated methods to make proofs on it.