The Design Of ST Developing Platform And Conversion To C Programming Language

In the international standard IEC61131-3,five programming languages of PLC are defined,including three graphical languages: Ladder Diagram(LD),Function Block Diagram(FBD),Sequential Function Chart(SFC),and two kinds of text language : structured Text language(ST)and instruction List language(IL).ST programming language is an advanced text programming language like PASCAL and C,which has a free programming format,and with strong data processing capabilities.We can achieve the complex control program easily using ST programming language.Therefore,the realization of the PLC software systems support for ST programming language,will greatly enhance the efficiency of PLC programming,complete the function of PLC platform.CASS system-a PLC software platform developed independently by Intellige nce and Control Laboratory of Hangzhou Dianzi University,has realized four languages for PLC programming,including LD,FBD,SFC and IL,and creatively implemented the embedded C in graphic language for programming.In order to improve the programming ability of CASS system,making it ful y compliant with IEC61131-3 international standard and being a specialized industrial control software programming platform,it is required to design and implement the support for the ST langua ge programming mode.Based on the CASS's abilities of embedded C programming language,we adopted the thought of language translation-translate ST language to C language,to achieve ST for programming.After a lot of research of the characteristics of ST programming language and the convertion technical between languages,we proposed a convertion algorithm,which make the syntax analysis as the core,recognize and process the source program grammer unit recursively.The algorithm consists of ST language lexical analysis algorithm,recursive descent parsing,generating control flow analysis technique based on the conversion algorithm and C language code generatio n.Besides,we realized the design of ST language programming platform.In the end of the paper,the validity of the conversion algorithm,source code expansion,the degree of automation conversion properties were verified through theoretical proof and a large number of experiments.Experimental results show that the conversion algorithm we designed,not only implement the ST language to C langua ge automatically converted,but with a smaller source code expansion.