Applying REMES behavioral modeling to PLC systems

Programmable logic controllers (PLCs), as a specialized type of embedded systems, have been introduced to increase system flexibility and reliability, but at the same time to give faster response time and lower cost of implementation. In the beginning, their use brought a revolutionary change, but with the constant growth of system complexity, it became harder to guarantee both functional and extra functional properties, as early as possible in the development process. In this paper, we show how formal methods can be applied to describe PLC-based systems and illustrate it on an example of a car wash system. First, we show how the existing behavioral modeling language Remes (REsource Model for Embedded Systems) can be extended to model the behavior of such systems. Second, we show how Remes can be translated into networks of timed automata and priced timed automata in order to support safety and resource-wise reasoning about PLC systems. The formal verification of PLC systems is carried out in the Uppaal and Uppaal Cora tools.