A Petri Net formal design methodology for discrete-event control of industrial automated systems

Increasing complexity of Industrial automated systems requires high level discrete event control implementation in programmable logic controllers (PLCs). To date most PLC applications for industrial discrete event control systems (DECS) are basically heuristic, mostly supported by partial system analysis and limited performance evaluation. Consequently the application of formal methods in PLC programming became extremely essential for industrial automation. During the past few decades Petri Nets (PN) have evolved to a very promising formal tool to establish an integrated solution for modeling, analysis, simulation and control of industrial automated systems. This paper presents a methodology for implementation of high level DECS PN models in PLCs using IEC 1131-3 standard programming languages. The produced PLC code is completely dual to its original PN model capturing completely its dynamic properties and can be fully restored directly from its PLC code. The flexibility of the PN models is reflected in the DECS's PLC code being simply and accurately updated following the changes conducted in the DECS's model.