In: Proc. 2000 American Control Conference, 28-30 June 2000, Chicago, IL, Vol. 5, pages 3165-3166. 2000.
Abstract: Petri nets are able to express the causality as well as the concurrency of a control algorithm. Signal interpreted Petri nets (SIPN) show good properties to model controllers. In SIPN the firing of a transition depends on input signals from the environment and the SIPN influences the environment via output signals. Since the function of a logic controller is basically determined by software, the question of software quality arises in this area. ISO/IEC9126 defines six characteristics of software that can be used as quality criteria. The six characteristics are set in the framework of controller design: the functionality and reliability of the software rely on the correctness of the algorithm. In this paper criteria for formal correctness of SIPN control algorithm are given and it is shown how they can be evaluated using the SIPN reachability graph. Due to a close relation between sequential function chart (SFC) according to IEC1131-3 standard (IEC 1992) and SIPN the criteria are also valid for SFC.
Keywords: signal interpreted Petri nets.