Formal Verification of Industrial Controllers: with or without a Plant Model?

The use of a plant model on formal verification of industrial controllers makes the formal verification tasks more realistic, because any industrial system is always composed by a controller and a plant. Therefore, if the plant model is not used, there is a part of the system that is not considered. However, if there are some cases where the use of a plant model becomes the formal verification results more realistic and robust there are another cases where it nor always happens. In this paper there are indicated which are the circumstances where it is useful to use, or not, a plant model on formal verification tasks, using model-checking techniques.