Petri net versus Ladder Diagram for controlling a process automation

Abstract

Industrial automation is constantly expanding, and, regarding their control more and more solutions are presently developing on the market. These include older methods like Petri nets (1966), and standardized languages, which are commonly used in the field of programmable logic controllers (PLCs). The paper presents the Ladder Diagram programming language, that is one of the standardized languages, and one of the most widely used for industrial automation systems. In these circumstances, it is useful to make a comparison between the two methods, drawing out the advantages and the disadvantages of each solution separately. Petri nets benefit from the existence of a highly developed mathematical support and high flexibility in analyzing all elements that can influence the conduct of an event, which is a major advantage. On the other hand, the Ladder Diagram language, which corresponds to the standard IEC 61131, is easy to use and implement, regardless of the hardware structure used by the manufacturer. Also, this method allows both ON-line and OFF-line simulations of the automation process operation. Finally, an educational platform is also presented.