Research And Implementation Of Construction Machinery Embedded Soft-PLC Programming System

With the continuous development of modern embedded technology and control technology, construction machinery controller has developed from the traditional PLC to the embedded soft-PLC. Embedded soft-PLC system consists of the programming system and the running system. The programming system is an indispensable part of the controller system, and it is primarily responsible for project management, programming, conversion compiling, debugging. At present, foreign advanced automation software company’s products occupy most of the domestic market at controller development environment, and some problems of programming system such as difference of programming language, unfriendly operating environment are the mainly obstacles to our development of control procedure.In response of these issues, a programming system of construction machinery embedded soft-PLC with IEC61131-3standard was designed and implemented. Aimed at the problems of complexity and management of the Ladder instruction, the common instructions and control algorithm were inductively classified, and hierarchical inheritance and factory method pattern were used to the management and addition of the instructions. According to the features of the ladder language editing, a method based on grid of storing and displaying ladder was proposed, which provided error detection mechanisms to prevent misuse operation; The ladder logic structure usually is very complexity, and it can’t be understand by embedded soft-PLC directly. In order to solve this problem, a language conversion algorithm based on energy flow was presented, which could diagnose logical relationship and transform ladder to instruction list accurately. In addition, grammar rules were checked during the conversion process, so the reliability and accuracy of transform is guaranteed.According to the working principle of the PLC, a simplified target code explanation virtual machine was designed, and the editor function, transform function and simulation function of the programming system were tested. Finally, a specific simulation example on JZ350conical concrete mixer was given, and results showed that the programming system of construction machinery embedded soft-PLC is easy to use, could generate code accurately and effectively, and could meet the general control program development needs.