Improving verification and reliability of distributed control systems design according to IEC 61499

It was shown in former publications that, in principle, the design of a distributed control system according to IEC 61499 could be proven to be correct. An implementation of such a control system should run correctly. But there are known issues regarding the specification and implementation of IEC 61499 function blocks execution models, which cause a verified control system design does not necessarily resulting in an implementation with the desired behavior. Another issue influencing the verification process is the granularity of the formal models used for verification. Bringing more plant properties (i.e. time related) into formal models for closed-loop verification will improve the verification process and reliability in its result. In this contribution the authors want to draft a way of covering the above-mentioned issues using the known Net Condition/Event Systems (NCES) as formal models.