Study On Profibus And Modbus Protocol Conversion And Its Application In The Intelligent Electric Actuator

With the development of computer and microelectronic technology, the electric actuators are developing toward a digital and intelligent direction. Among them, the intelligent electric actuators based on the fieldbus technology have become a research hotspot in this field.As one of the core technologies for modern control system, fieldbus is the synthesis of the computer and digital communication technology. It can realize the digital communication between distributed nodes. There are many standards for fieldbus protocol and the scope of application for them is greatly different. Profibus-DP and Modbus are widely used in the control system, but they have the communication barriers between each other because of different bus interface and data structure. The main work of this paper is to design a protocol conversion module,so that the data can be transmitted normally between the two kinds of fieldbus and expand the range of use for devices which are designed based on the two kinds of fieldbus protocol. The main research contents are as follows:(1) Through analyzing the data transmission mode and data structure, the technicalcharacteristics of the two kinds of the fieldbus protocol were studied as well as the data formattransformation during the process of protocol conversion.(2) Before the design of the protocol conversion module, the important parameters of themodule were analyzed. Then the research on protocol conversion principle and model, the hardwaredesign and software design for the module were finished. On the basis of the design, the PCB boardfor the protocol conversin can be made.(3) The control system for the intelligent electric actuator was designed. First, the parametersfor the control system were analyzed and calculated. Then, the hardware and software design forthe control chip, motor and analog-digital conversion module was finished.(4) The module was tested through the communication test and the results indicate that it cancomplete protocol conversion very well. The output torque was tested and demarcated to test theworking conditions of the actuator. The performance of the control system was tested through theapplication experiment. It was shown that the design can meet the design requirement.