Specification and analysis of real-time systems in Statecharts

Increased use of software in controlling safety critical systems produced an urgent need to specify and analyze behavior of these systems systematically and rigorously. Statecharts formalism, a popular extension of conventional finite state machines, has been successfully used for specifying requirements of many reactive systems including the TCAS II, an aircraft collision avoidance system. However, little has been published on specific guidelines on how one can best specify and analyze requirements in Statecharts. We present a framework for specifying requirements of real time systems in Statecharts and analyzing them for completeness, consistency, and safety. We use the requirements taken from an emergency shutdown system for a Korean nuclear power plant, called Wolsung SDS2, as an example.