Structural Synthesis of PLC Program for Real-Time Specification Patterns

Among all the reactive synthesis methods, the results of the structural synthesis have the best interpretability and traceability. However, existing structural synthesis method cannot deal with real-time specifications and specifications with circular dependencies. A structural synthesis method for Programmable Logic Controller programs is proposed. First, a real-time specification pattern language, RTSPS4Syn, is proposed. Under the condition that there is no circular dependency between the specification items, the implementations of a specification item are assembled structurally from the implementation of its scope and property expression; and the programs for the specification items are concatenated according to the order of priority and dependency to obtain the synthesized program. This paper presents a method to eliminate the circular dependence of specifications, such that the synthesis approach can be applied to specifications with circular dependency. Furthermore, this paper presents an approach for setting the preset values of timers when considering tolerance on the duration of the delay. The synthesis method does not need to check the conflict and determine the nondeterministic part of the specifications. These problems are solved in existing research by constraint solving in PSPACE.