PLC PROGRAMMING LANGUAGES : A FORMAL APPROACH

This paper introduces describes how to integrate standard editing and code generation functionalities offered by most tools supporting the IEC standard 1131-3 with capabilities for modelling and simulating the plant and its interactions with the digital controller. The 1131-3 notations (in particular Functional Block Diagrams) are complemented with differential equations that describe the behaviour of the plant and with an underlying formal model, which supports the analysis of functional and timing properties.