A Petri Net-Based Controller for Flexible and Maintainable Sequence Control and its Applications in Factory Automation

A new type of software system for an industrial sequence controller is proposed. In this system, a control program is described with the Petri net-like language named Control-net (C-net). This language improves control software maintainability and flexibility. An efficient C-net interpretation schema for real-time control is presented and an overhead time evaluation model of the proposed schema is developed. Through the model analysis and measurement of the response time of an interpreter on a microcomputer, it is proved that the interpretation schema satisfies the required response time. Finally, a microcomputer based controller named Station Controller (SCR) in which the presented C-net interpreter was installed is described and several applications of this controller to real systems are illustrated.