Modelling System Specifications on a Finite State Machine

Abstract

CODE (COntrol Definition language) is a formal language designed and used for implementation of control strategies in sequence control applications, such as found in industrial control. CODE treats processes as finite state machines (FSM), by defining transition conditions that determine when a state change will occur, and the consequent transition action. A control definition consists of a hierarchical model, each layer of which consists of a number of FSMs. The CODE concept is proposed for use in a formal specification language, that would form part of a specification work bench, including syntax-c hecking editors, consistency and completeness checks, automatic simulation and documentation systems. This work bench will provide a powerful tool for specif i cation and development of process control and other systems. It will help increase the effectiveness of software designers and engineers; it will also contribute to increased formality in system specification, helping to eliminate a major source of error.The CODE concept is thus part of the current trend towards increased automation of software development. It can be used to develop formal system specification languages that are application-specific, and that can be part of a semi-automatic system generation process, in which the system specification is transformed directly to the implementation. Maintenance is then performed on the specification, which is reimplemented with computer assistance.