Automatic generation of ladder diagram with control Petri Net

This paper presents a design method to generate a ladder diagram (LD) automatically with the control Petri Net (CPN) for control of discrete event system. This method describes the specification of a practical system with the CPN that associates operations with places and conditions with transitions. Based on the firing regulation of transition, the relationship of places, conditions, and events are formulated with Boolean functions. These functions can be easily converted into LD and implemented on a programmable logic controller (PLC). An application example in a liquid mixture system shows that the proposed method is effective and has the advantages of ease of understanding, modification, and maintenance.