Applicability of supervisory control theory for the supervision of PLC programs

The safety of software-based control systems plays an essential role in a vast number of applications. SynTACS is a tool that generates a framework for controller supervision, which enforces safety during runtime by utilizing the supervisory control theory of Ramadge and Wonham. In this paper, the results of a user study are presented in which it was investigated how far discrete-event systems, the underlying modeling formalism, are suitable to express safety requirements. Further, the usability of the tool was evaluated. In the second part, several concepts are introduced to support use cases that require real-time controllers due to unstable processes. Finally, two case studies are presented to show the applicability of both the tool and the new concepts.