Formal verification of UML-modeled machine controls

Programmable logic controllers (PLCs) are applied in a wide field of application and, especially, for safety-critical controls. Thus, there is the demand for high reliability of PLCs. Moreover, the increasing complexity of the PLC programs and the short time-to-market are hard to cope with. Formal verification techniques such as model checking allow for proving whether a PLC program meets its specification. However, the manual formalization of PLC programs is error-prone and time-consuming. This paper presents a novel approach to apply model checking to machine controls. The PLC program is modeled in form of Unified Modeling Language (UML) state-charts that serve as the input to our tool that automatically generates a corresponding formal model for the model checker NuSMV. We evaluate the capabilities of the proposed approach on an industrial machine control.