软PLC梯形图向指令表转化的算法研究与实现

Research and Implementation of Algorithm from LD to STL in SoftPLC

梯形图与指令表是PLC中最常用的两种语言。其中梯形图形象直观,易于编程,但梯形图往往需要转换为指令表语言才能在PLC运行系统中解释执行。针对上述问题提出了一种适用于数控机床软PLC的梯形图向指令表转换的算法。该算法基于AOV图映射,将梯形图程序存储为邻接表数据结构,采用拓扑排序方法将邻接表中内容按指令表逻辑顺序输出,最终实现梯形图向指令表的转化。论文给出了该算法在自主开发的软PLC中的一个应用实例,描述了梯形图向指令表转化的主要思想和实现过程。

Ladder diagram and instruction table are the two most commonly used language m the PLC Ladder diagram for its intuitive image is easily to program,but for being interpreted and executed by the PLC runtime system, it often need to convert to instruction table. In view of the above question, an al- gorithm of transformation from ladder diagram to instruction table for the soft PLC of CNC machine tools is presented. Basing on AOV diagraph, Ladder diagram is stored for adjacency list in this algorithm, and the contents of the adjacency list are output according to instruction table logical sequence by the topolog- ical sort method. Finally, the transformation from ladder diagram to instruction table is completed. An example of transformation in the self-developed soft PLC is given in the paper, which introduces the main idea of the algorithm and realization process.