Distributed Implementation of Hierarchical Grafcets through IEC 61499

The control software of manufacturing systems has to interact with the mechanical and electrical machine parts, hence, their engineering is closely interrelated. A high-level model of this system can provide an abstract view on the system's behavior and is therefore beneficial for any engineering discipline. The language GRAFCET was developed as a domain-specific tool for specifying the operation of a production system. GRAFCET models can be structured hierarchically to regulate the behavior of a subsystem with forcing orders and enclosing steps. Based on a Grafcet, control software can be implemented in the executable modeling language IEC 61499. In this paper, we describe a step-by-step approach for implementing hierarchical features of GRAFCET with IEC 61499 models. The resulting application is well-structured and thus maintainable.