Validating Programmable Logic Controller Systems with Duration Calculus

The programmable logic controller (PLC) system is a type of the hybrid systems, which is a widely used safety-critical system in industry. It is regarded that the formal method is a valuable and indispensable way of analyzing and validating the PLC systems. However, which formal methods and how to use the methods are challenges. In this article, we propose a specific formal method of the PLC systems, e.g., we formalize the PLC systems by the EDC formulae hierarchically, specify the property as the formulae, and then analyze and verify the system in the framework of the EDC calculus. So in fact we propose an EDC based hierarchical formal method of this type of system, we trust this method is applicable. We also harness two examples to demonstrate the effectiveness and feasibility of the method.