Within the engineering of control code, model-based approaches become more and more important. Basically GRAFCET serves as a suitable modeling language but lacks an exhaustive formal representation of its structure and dynamic behavior since current approaches only consider subclasses of GRAFCET. Within this article the authors depict a systematic approach for an exhaustive formal model of GRAFCET, specifically by taking enclosing steps, forcing orders and time constraints into account. Based on this formal model of GRAFCET a method together with a tool framework are presented allowing for the automatic generation of control code.