A Research On The Intermediate Language For Industrial Control Programming Language

Industrial control systems are a series of software and hardware that control the automated operations.They are widely used in industrial automation and some critical infrastructures.PLC is the most commonly used industrial controller.IEC 61131-3 is the first international standard about PLC control software programming language.By reference to the advanced programming ideas in software engineering,it provides a unified programming language standard for PLC control software development.And the standard solves the problems of openness,compatibility,and maintenance in traditional industrial control systems.IEC 61131-3 provides five types of programming languages to facilitate the use of different PLC programming engineers and adapt to different PLC application scenarios.This standard contains two texture programming languages,instruction list and structured text,and two graphical programming languages,ladder diagram,and function block diagram.Besides,sequential function chart is defined to describe the architecture and functions of the PLC control software.Designing different test and verification scheme for different languages will increase the complexity of test and verification.So the coexistence of multiple languages in IEC 61131-3brings a considerable challenge to testing and verification of PLC programs.After studying IEC 61131-3 standard in depth,this paper combines the features of the five types of programming languages to extend the formal modeling language CSP and proposes a concise intermediate language ICIL for the IEC 61131-3 standard.This language extends the notion of a statement and enhances its computational power relative to the CSP language.Also,a periodic scan channel has been added to describe the cyclic execution of the PLC program accurately.To accurately describe the ICIL language,based on the description of its grammar,the meaning of the language is expressed through the operational semantics.Operation semantics is a formal semantics which can be used to construct transition systems for ICIL programs.Based on these transition systems,the paper explored the formal verification method of PLC program.Also,according to the syntax of ICIL language and the characteristics of the standard languages,this paper proposes the translation method from the IEC 61131-3 to the ICIL language and implements the intermediate language conversion tool ICILConvertor.This paper illustrates the feasibility of the above conversion scheme through the conversion experiments of multiple application examples.The intermediate language,the translation method and the exploration of PLC program verification method are conducive to the integration process of PLC control software development and verification and will promote the construction of an industrial safety and security environment.