Research And Development On Industrial Communication System Based On Field Bus

The modern industrial production should take the market production planning, manufacturing process, after-sales service and business management as a unified production process to consider and adopt the computer, control and communications technologies to achieve a comprehensive process automation to improve production, processing and management decision-making. To achieve the information integration throughout the production process and comprehensive automation, it is necessary to design a communication system that is industrial site in operation, reliable and cheap. This system could achieve the multi-point digital communications between roboticized and intelligent scene equipments, forming factory-floor networks, and the realization of the information exchanged between the bottom equipments or the production scene with the outside world. Field bus is in line with the trend in the development.This paper leads to CAN bus from field bus by the description of the development of the background of industrial corresponding control system, which conforms to the decentralized and intelligent direction of control system. Thereby this paper launched the study on basis of industrial field bus communication system. The research of CAN bus protocol and the realization of the communication functions are the most difficulty in the research. This paper carries on the research and development of them.In this paper, CAN bus and international standard ISO11898 CAN bus communication protocol was described detailedly. And on the basis of the analysis, using Finite State Machine describes the protocol in formally. And through the establishment of a formal description of the CAN bus protocol model, we set a CAN node, including transmission, reception and fault state mode. According to the CAN message frame structure selected as a different stage of sending state for sending and receiving mode. Considering the most important part of the protocol—false definition, another five errors were selected as wrong states. There are sending wrong signs and overloading signs. Sent wrong signs made the differences of the sending activities wrong signs from the sending allowable wrong signs. Sending mode of CAN, described in detail the process of CAN nodesmessage. Receiving mode of CAN, described in detail the process of CAN nodes to receive messages. CAN nodes in the process of sending and receiving process is roughly the same. Because in CAN bus system, a process of sending node is the process of receiving. They are simultaneous. From the point of view of the false definitions, CAN bus nodes have three states that are error started, error permitted and closed bus. They express fault state mode of CAN.Then on the basis of the formal model, the communication performance of the bus system was tried to make emulation analysis. Simulation platform of the CAN Bus made Simple visual interpretation of MAC mechanism and dynamic simulation of communication activities. This analysis of the performance of CAN bus system provides great convenience.Formal description techniques can better overcome the shortcomings of natural language description of the agreement, the agreement can be fully express these characteristics, and provide a good foundation for the certification of the agreement and achieving conformance testing. By establishing a formal mode of this field bus protocol, one hand can help people's understanding of the bus protocol because the mode is more intuitive and the agreement is described as logic; on the other hand it can help people achieve agreement whether through software programming language or the formal simulation modeling software that are relatively easy to achieve. It is precisely the purpose and significance of this paper.On the basis of the above, then this paper made the construction of the smallest CAN bus communication system. The system is made of three parts. First described in detail the relevant chips of CAN including SJA1000 CAN Bus Controller, CAN Bus Driver TJA1040 and MCU AT89C51.Then this paper designed a communications nodes using them. The secondary node sends data to the primary node, and the primary node receives the data. And in order to achieve communication with the PC, I used RS-232 standard to do it. Then this paper constitute a complete CAN bus communication system. Hardware and software modules of communications nodes were designed in this paper and given a flowchart-related software and hardware design. The communications system constructed was test by the CANalyst analysis and serial debugging software. Finally the communications functions were certified.Control system of CAN bus led to a traditional structure changed and madethe formation of a new integrated network-wide distribution control system that called field bus control system. It is a new generation control system after the base control systems, electrical instrumentation and control system simulation modules modular, centralized digital control system Distributed Control System (DCS), which conforms to the decentralized and intelligent direction of control system.The rising of field bus technology has opened up a whole new factory-floor network. It will promote the rapid development of enterprise networks and bring new benefits for the company. CAN bus is the most effectively support a distributed real-time control system and a kind of real-time datum bus. It was paid the widely attention by the industrial sectors and been widely applied, because of its outstanding features, the unique design and the reliability of communications. It will definitely push forward the development of related industries. This paper made the study of its key technologies. It will accumulate precious experiences for developing field bus control systems in internal industries. It also play a positive role for the promotion of CAN bus in the industrial area. This industrial communication system of CAN bus that this paper constructed has provided the foundation for the application of CAN bus to the industrial network systems and has great practical significance.