CONSTRUCTING AN ABSTRACT MODEL FOR LADDER DIAGRAM DIAGNOSIS USING PETRI NETS

Abstract

This paper proposes a method for constructing an abstract model for analyzing and diagnosing electrical circuit ladder diagrams (LDs) using Petri nets, and also supporting network-based monitoring and supervision. This approach converts normal open (NO) and normal close (NC) contacts in the LD into Petri net transitions, and converts devices (e.g. relay coils) in the LD into Petri net places. This study introduces the concepts of composite transitions, composite places, and relevant state to reduce complexity and increase readability of Petri nets for constructing abstract models. The current study constructing diagnosis of fault modeling, introduces simple matrix manipulation and the difference output vector (DOV) to determine the faulty area for diagnosis in the ladder diagram. An LD controller example demonstrates the usable approach.