| Programmable logic controller (PLC) plays a very important role in modern industrial automation. The functions of PLC have been expanded to a great extent after about forty years of improvement, and most of the PLC productions have already possessed the functions of motion control, such as location, line interpolation, circular interpolation, etc. PLC has widely used in motion control areas, because of its superior sequence logic control ability, high reliability, compact structure, easy to enlarge, easy to develop and other characteristics. Nowadays, widely adopted PLC programming methods use motion control instructions or functional models to implement motion control programs, which would result in the faults of large amount of codes especially when the motion control process is complex. In this way, any parameter or motion sequence change would lead to the modification of PLC program, which reduces the development efficiency and brings about a lot of maintenance and optimization problems.To resolve the problems mentioned above, this paper propose a method to construct numerical control language based on PLC. With numerical control language, the maching process can be described in a flexible way by making the best use of PLC motion control and logic control function. This approach can be conveniently adjusting the sequence of motion control and setting parameters, which improve the developing efficiency greatly. The main work is including:First, This paper make in-depth research in the technology of PLC motion controlling and analysis the development situation. In the term of current existing problems, this research is necessary and feasible. The overall framework of the system is composed of design a numerical control program complier for upper computer, PLC control program and program execution control algorithm. Second, this paper proposes a PLC multiplayer driven structure model, make in-depth research of the relationship between all levels of PLC, then design and analysis of numerical language implementations. The main steps consist of CNC instructions design, CNC multi-language layer building, CNC program compiling and execution. CNC instructions function is using the modular programming method of ladder diagram, which has the virtues of encapsulation and reusability. Finally, the validity of this method is verified by an illustration. The effects of building CNC language on the customized PLC that has the function of motion control are satisfactory, which control multi-axis winding machine automatically. The result shows that through this paper, the method of multi-layer driven architecture in PLC to construct numerical language, not only can improve the PLC control program development and debugging efficiency, but also can develop numerical control language to different application rapidly. |
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