The new interconversion algorithm between ladder diagram and instruction list

In the application of PLC (Programmable Logic Controller), ladder diagram is visual and easy to control by engineering staff, besides, instruction list is easily convert into assembly language program, so they are favored by technicians, so that the research of interconversion between ladder diagram and instruction list become a key technique in development of PLC. The conversion algorithm in present is maps ladder diagram to AOV graph, then it realizes the interconversion between ladder diagram and instruction list by sorting AOV graph, but efficient of the algorithm is lower. A new algorithm about interconversion between ladder diagram and instruction list based on forest and binary tree is presented in this paper by the research and analysis of ladder diagram´s language and instruction list on PLC. At first it maps ladder diagram to forest, and then it establishes a binary tree to represent ladder diagram logical relationship with forest At last it realizes the exchange of PLC ladder diagram and instruction list by traversing binary tree. The algorithm is simple and rapid, its correctness and feasibility are verified in programming software platform of PLC.