Sensor-based Petri net modeling for PLC stage programming of discrete-event control design

Petri nets have been extensively applied for specification, design, verification, performance evaluation, and simulation of discrete event control systems (DECS). This paper proposes a real-time stage Petri net (RTSPN), to represent the stage programming of a programmable logic controller (PLC) for DECS. The new technique is able to simplify the design process of the complex PLC program without considering the interlocking problem within the ladder diagram. An illustrated example is used to explore the new methodology. The proposed method contains the power and flexibility of the Petri net analysis. It is believed that this technique is significant for the industry practice.