| With the development of intelligentized,networked and distributed control system.FCS(Fieldbus Control System),which is a new absolutely distributed control system,came into being.It has powerful life and will take a epochal change to the structure of control system and automation technology.Fieldbus is a kind of digital,bi-directional transmission and multi-branch communication network which connects intelligent equipment and automatic system.It is the production of synthesis and integration of computer technology,communication technology and control technology.It is a kind of network,and can transmit numeric signal on two directions among many nodes,which is applied in buttom layer of industry control fields.According to these characteristics,fieldbus not only increases realibity,anti-jamming of all control system,but also can save greatly expense of investment,installment and maintenance;Field facilities possess intelligence,inter-linkage and mutual operation,which conduces development of fieldbus to decentralization,intelligence and network.It's an open and distributed new pattern and a focus of automatization.The development of fieldbus and application of that must arose a profound change in industry control fields.CAN is a kind of fieldbus and a serial communication network which supports distributed and real-time control effectively.CAN Bus is one kind of fieldbus which has the characteristic of low cost,fast speed,high real-time and reliability.Thus,CAN becomes one of the international fieldbus standards.But its application is not limited in automobile industry for its excellent performance now.I'ts also applied in auto control,building automatization,mechanical treatment equipments,and so on.Intelligent control is the advanced stage of control theory and techniques.It's a new and developing research field.It's used to solve the problem of control of complex systems which are not easily solved by traditional control methods.In this paper,we analyze the CAN 2.0B protocol first and a model of CAN control system is established.In the following part,we design the CAN nodes and the software to realize its performance.This paper developed a distributed control system based on CAN Bus.Many relatively advanced techniques which are involved to control,communication,network and circuit design techniques are used in the system.The system possesses good capabilities of control and monitoring,and steady performance, good scalability and good performance-cost ratio.Distributed control system based on CAN Bus will be used in monitoring,protection and management of nuclear medical equipment.It is constituted by major control computer in control center,USB-CAN converter card and control node located in various parts of the electronic control unit.Control node can achieve the monitoring of the electronic unit independently,and can carry out information exchange through CAN network and the host computer.USB-CAN converter card can complete the CAN Bus protocol conversion between the USB protocol.Host computer can achieve the communication with CAN control nodes based on CAN network in order to form the decentralized supervisory control and centralized management in one of the distributed control structure.The paper summary is as follows:(1) Analysis the field bus control technology concept and the characteristic, the network architecture and the model(2) Introduced the features,hierarchical structure of CAN(Control Area Network)Bus.(3) Elaborated the design of Distributed Control System based on CANBus,,including the design of the overall structure, the design of hardware and the design of communication software.(4) According to the overall design requirements, designed the CANBus application layer protocol.(5) Through many times to the supervisory system function test experiment, system obtained the comprehensive examination.The experiment indicated the system has high real-time performance,strong anti-interference ability and good scalability.It achieved the desired objectives. |
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