Implementing PN-based controller with mutually exclusive transitions by SFC

In this paper we propose a method for implementing the controller synthesized by PN based SCT theory. Despite the great acceptance of SCT in controller designing, there are problems with its practical implementation. Sequential Function Chart as an international standard programming language is used for implementing PN-based controller. One problem in this way is occurrence of simultaneous events in mutually exclusive transitions. In SFC standard there is left to right priority. In this paper, we present a method to developing dynamic priority. If two users have requests for the common resource simultaneously, priority goes to one that in previous turn has not use of resource. Finally, we illustrate the idea using an example.