Generation of PLC Ladder Diagram Using Modular Structure

Abstract

In this research work, auto-generation of PLC ladder diagram program is explained. This work is carried out in real time operation of PLCs in the plant and simulation of the models in the PlcStudio <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">reg</sup> . Involved modelling and simulation tasks are performed in PlcStudio <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">reg</sup> which is research product of digital manufacturing system (DMS) team in Ajou University, consists of input/output model and graphics tool for PLC based industries. Object-oriented approach DEVS (discrete event system) is employed in formalism of process structures, later, formalized model is simulated using plc-DEVS simulator, which is extended from conventional DEVS. Generated sequence of operation (SOP) from the simulation and mapping it into input/output table to generate executable ladder diagram is explained consecutively in the paper. The algorithm developed to connect plc-DEVS and graphics module of PlcStudio <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">reg</sup> is elaborated. In the mean time, to show the applicability of methodology, pallet conveyor system is described.