Interpretation Petri net model to IEC 1131-3: LD for programmable logic controller

Programmable logic controllers (PLCs) are widely used in industry. Thus PLCs usually use the IEC 1131-3 standard programming language. The ladder diagram is the most popular language which does not require a lot of the steps and sequences of the operation. Therefore it is difficult to understand the program structure and developing the system. The Petri net is a graphical model that can explain the system operation easily and clearly. This paper presents the transformation structures from Petri nets to ladder diagram and possible implementation to control the process through the PLC's input and output.