The Automatic Module Based On CAN And It's Application

Fieldbus is a kind of communication network which is a whole digitial communication multi_embranchment data bus between intelligential field device and auto_system .Control system based on PCS ( Fieldbus Control System) is a new kind of system which connect field control unit,field monitor unit,operation unit ,communication interface uint with databus.lt integrates computer technology,communication technology and process cnotrol technology to adjust to demand of high standard productive control and enterprise management.lt developments and follows the advantage of traditional instrument control system and computer central control system and make up for their disadvantage so that it is applied in different industrial cnotrol area. With its new frame .modern technology,complex information dispose and unique control mode,it embodys an idea which is information centralized and control decentralized.Its main advantage is system open and interchange and its frame is so simple that it can decrease producative .cost and maintenance load.As it is a new technology,there are different kind databus standards which adapt to different control area.This papaer firstly introduces field bus'sframe work,function,type,compares distributed control system and field control system.Then it focuses on introducing CAN protocol and CAN control chip SJA1000 and CAN interface chip 82C250,At last,it introduces how to set up a typical automatic control model based on CAN .This model can be used in practical industrial control area and management area by appropriate change.As a practical example ,this paper introduce tension cortrol system based on this automatic control model.lt recommends each automatic control model 'work principle and process control idea. Each automatic control model has function dispersion and can deal with parameter checking,calculation,control strategy, information output and process parameters time_control.These functions will auto_run effectually and reliably that make control dispersion. Field bus intelligential model layer in this system is made of a few intelligential models in the each automatic control model.which can make whole control system effectively work and overcome each module own's control error through data and information exchange .This system adopt not only RS485 but also CAN.lt has whole digital bilateral comrnunication,multi_parameter deal,self_check etc.In the whole system,each intelligential uint work in dependency and intercommunicate.The user can freely configure to realize different kinds functions according to their demands.The advantage of field bus embody the character and advantage of control system based on fieldbus.