Design And Implementation Of Ethernet Serial Server Based On ARM9

Ethernet enjoys the advantages of low cost, high communication speed, unrestrictedcommunication distance, flexible networking, sufficient hardware and software resources. Atthe same time it also has a mature technical support. And these advantages make it developrapidly and widely applied in recent years. Various fields have begun to use Ethernet-basednetwork interconnection devices widely. All terminal devices join the network has become aninevitable trend of the development of communications. Serial communication possesses thefeatures of simple transfer protocol, high reliability, easy to implement and safe in closecommunication. At present, a great number of terminal equipment at home and abroad stilladopts the traditional asynchronous serial interface, such as RS-232, RS-485, etc. However,serial communication is limited to transmission distance and inaccessible to the mainstreamnetwork. In the Internet era, the device data in many applications require remote networktransmission, which demands for the implementation of centralized, comprehensive, accurateand real-time data monitoring. Because conventional serial interface devices and existingnetwork devices have interconnected problems, therefore this paper uses serial server to allowserial port device to access to Ethernet and carry out data transmission under the premise ofno replacement of old equipment and avoid consuming a lot of manpower, material resources.Serial server allows multiple serial devices to connect to the Ethernet simultaneously, realizesserial data transmission in real time via Ethernet, executes two-way communication with aremote host device, eliminates limitation of the original serial interface device to thetransmission distance and achieves the network management and monitoring of serialinterface device.The main significance and role of serial server in the base station ID monitoring systemare introduced in this paper. The Freescale iMX257processor embedded with ARM926coreis utilized as the hardware core and the system firmware is composed with embeddedWindow CE6.0real-time multi-tasking operating system and C#. Finally a completemulti-channel serial server design is achieved and the PC configuration software is developed.Through the analysis on the demand for multi-channel serial server, the overallarchitecture design of the system and the hardware circuit design of core modules, serial portexpansion module, RS-232interface and the Ethernet interface are completed in the paper.Aiming at the key technological problems of serial server and by analyzing the factors thataffect the performance of serial server, problems of the data framing technology and the databuffer size existing when data are transferred from serial interface to the network have beenpointed out. Additionally, appropriate solutions have been proposed. There exist a number ofoperating modes for TCP/IP in the serial server and one that is most suitable for practical applications is chosen. The software design and implementation of system firmware programand PC configuration program are completed on the basis of an analysis of the keytechnologies in the serial server.