GRAFCET — Basic concepts

It has been observed that graphical representations are increasingly preferred to literal and algebraic representations for describing system behavior, because of their ability to serve as a communication medium between all those involved (specifier, designer, producer, operator, maintainer). The fact that all these players can dialogue and express their points of view as part of the development process for an automatic system is in itself a considerable help, firstly for specifying, and then for carrying out (partial) validations of this specification. It was with this in mind that GRAFCET (Graphic functional command stages/transitions) was conceived. This specification language provides a functional description of the behavior of the sequential part of control systems. It is standardized, taught in secondary and higher education, and used in industry. A revision of this standard was published in 2002 to adapt it to new user requirements.

This text is a new edition of the dossier written by Paul BRARD, from which it takes some passages.

This subject is covered in two separate files, so readers should also consult the fascicule which completes the present file.