Development of Safety-Critical Real-Time Systems

This paper presents an approach to the development of safety-critical real-time systems linking from the Requirements Language developed in the ESPRIT Project ProCoS to the Temporal Language of Transitions (TLT) speciication language developed at Siemens Corporate Research. A system is deened by a conventional mathematical model for a dynamic system where application speciic states denote functions of time. Requirements are constraints on the system states, and they are given by formulas in duration calculus (DC), a real-time interval logic. A functional design is a distributed system consisting of sensors, actuators, and a program which communicate through shared states. The sensors and actuators are speciied in DC while the program is speciied in TLT. The design as a whole is linked together semantically by using a DC semantics for TLT. Veriication is a deduction showing that a design implies requirements. The TLT speciication is the basis for developing the control program. The method is illustrated by a steam-boiler example.