The formal design of distributed controllers with dSL and Spin

We study the formal verification of programs written in dSL, an extension of the standard ST language used to program industrial controllers. It proposes a trade off between industrial and formal verification worlds. The main advantage Of dSL is to provide a transparent code distribution through low level communication mechanisms. The behavior of the synthesized distributed system can therefore be formally modeled, easily monitored and formally verified. The verification of a dSL program, realized with the Spin tool, is eased by the definition of a lattice of models linked with a simulation relation preserving next-free LTL formulae. We show that, although dSL is an industrial programming language, it gives the possibility to verify systems designed with it. We illustrate the benefit of our approach with a simple control system of two canal locks.