Research Of Ethernet/Ip And Modbus-TCP Communication Adapter Based On Dual-port RAM

In recent years, industrial automation control systems develop towards intellectualization,informatization and networking. In the early years, industrial network commonly adopted thecommunication interface based on the way of serial such as RS232 or RS485 and so on. Withthe development of computer technology, fieldbus technology such as DeviceNet, Profibusand so on born, and with the rapid development of EtherNet technology, industrial controlsystem will be "netting to the end" by using industrial EtherNet is the inevitable trend of thedevelopment in the future. At present in all of the network technologies, EtherNet technologybased on TCP/IP protocol has been the standard network. In fact, EtherNet/IP andModbus-TCP are the industrial EtherNet technologies which are based on the commoncommercial EtherNet whose core technology is TCP/IP protocol and have good applicationpromotion prospects and huge economic value. But be compared with the vigorousdevelopment of industrial EtherNet, the traditional industrial equipment generally do not havethe industrial EtherNet interface and communication function, so how these devices accessindustry EtherNet becomes the problem which requires solution immediately.This paper based on the above background and the analysis of the EtherNet/IP andModbus-TCP industrial EtherNet protocol puts forward the solution of double industrialEtherNet communication adapter, completes the software and hardware design of thecommunication adapter, and eventually proves the rationality and validity of the hardware andsoftware design of the communication adapter through the corresponding experiments.This paper firstly analyzes the system structure, communication principle and the dataformat of the EtherNet/IP and Modbus-TCP industrial EtherNet, then by using the physicalstructure of the core board module with the CPU of Samsung’s S3C2440 and bottom boardmodule, by using the dual-port RAM as the data bridge for exchanging data with the outsideapplication equipment, and by using the core board interface circuit, EtherNet circuit,communication instruction circuit, reset circuit, external data exchanging circuit as the corecircuits for the bottom module designs the hardware system of the double industrial EtherNetcommunication adapter based on the EtherNet/IP and Modbus-TCP protocol. Also this papertransplants the embedded operating system Linux on the hardware circuit of the target board,and completes the EtherNet/IP and Modbus-TCP communication software development basedon the protocol stack program and the hardware driver development of the dual-port RAMunder the embeded Linux operating system. Eventually this paper uses the HC-100 intelligentmeasurement and control instrument as the target outside application equipment, and by usingthe communication adapter accesses the HC-100 measurement and control instrument intoEtherNet/IP and Modbus-TCP network respectively, finally finishes the integrity test of thesoftware and hardware through the EtherNet/IP host interface card which is produced byWoodhead company and the Modbus-TCP superior master station software for the communication adapter. The result of the test verifies the rationality and validity of thehardware and software design of the communication adapter, provides a theoretical basis andpractical experience for the subject in the further research.