Design Of Embedded Gateway Base On Heterogeneous Multi-protocol

With the development of industrial technology, industrial field device network,and control remote technology become a new trend. But in the traditionalinstrumentation equipment, the majority of field devices using either the RS485interface or CAN communication interface. The RS485bus network and CAN busnetwork could communicate with devices in their own network respectively within acertain distance, but not interoperate nor information share. The rapid development ofEthernet technology provides for the field device to network. This paper presents aheterogeneous embedded microprocessor LM3S8962-based communication gatewayto solve the underlying device industry in heterogeneous network cannotcommunicate with each other that meet the underlying device connected to theEthernet traditional industries needs to achieve the purpose of sharing information.Firstly, a systematic analysis of the overall architecture of the communicationgateway is designed, then the Modbus standard protocols, and CAN bus data protocolframe format are introduced. On this basis, the functions needed to implement in thecommunication gateway is designed in theory. Packaging and delivery process data incommunication gateway illustrates the design of the protocol conversion. A layereddesign is adopted for the software versatility and then the conversion design of themiddleware protocol and the process of data stream are discussed. The new design ofbuffer method and register map method is proposed to resolve the difficulty that therate does not match between the different networks.Secondly, The paper describes the detailed design of the circuit to achievecommunication gateway. The LM3S8962core system circuit is achieved to meet theneed of basic functions of the processor running. The peripheral circuits are achievedinterface function of the communication gateway, including CAN bus interface circuit,RS485interface circuit, Ethernet interface circuitry, EEPROM memory circuits,large Flash memory interface circuit and so on. The architecture of software design and the implementation of heterogeneous communication gateway are elaboratedincluding the ports of uC/OS-II real-time embedded operating system on theLM3S8962microcontroller, embedded TCP/IP protocol stack LWIP, communicationthrough TCP connecting and the task management in multi-tasking system.Third, the Ethernet collision detection mechanism--CSMA/CD (Carrier SenseMultiple Access/Collision Detection) works with Collisions the arbitration algorithm-binary exponential back-off algorithm BEB and its limitations for collision isdiscussed and an improved BEB algorithm is proposed. Mathematical theory analysisand computer simulation are adopted for data simulation for calculation andsimulation. According to the results of Matlab simulation, the average queuing delaytime has been reduced even in the case of heavy load as same as the Ethernet terminalto send a data collision probability. The improved BEB algorithm has effort on theperformance of the real-time Ethernet improvement.Finally, the industrial electric heating equipment for laboratory testing,embedded heterogeneous communication gateway in heterogeneous networkcommunications, stability and real-time to meet the design requirements, an effectivesolution in heterogeneous network devices in a multi-master fieldbus communicationconflict the questions, complete multi-protocol data between heterogeneous networksframe conversion and communication...