SUMMARY
This paper focuses on formal verification and validation of a model dedicated to mode handling of flexible manufacturing systems. The model is specified using the synchronous formalism Safe State Machines. A structured framework for the design process is presented. The obtained model is characterized by a strong hierarchy and concurrency that is why within the design process an iterative approach for specification, verification and validation is propose in order to improve this process. The main properties being verified are presented and the approach is illustrated through an example of a manufacturing production cell.