Research On Ethernet Interface For Device With RS-232 And USB Port

The convenience of network has become more and more favorable with the development of Internet technology. Developed with the Ethernet industrialization and the development of the computer bus-mastering technology, the networking of test & control equipment has been promoted quickly according to the requirement of the long-distance inspection work.In our country, RS-232 and RS-485 interface had been adopted normally to the equipment in the early periods. With the development of USB technique, more companies are trying to produce the equipments which can support data transfer of USB. In order to realizing better resource sharing, remote monitoring and controlling, the solution of networking of the electric equipment is necessary to coincide with the rapid development of network technology.This paper analyzed the current situation and the development tendency of industrial Ethernet previously. Then based on the existed RS-232 standard and USB protocol, data transmission modules of both RS-232 and USB can be designed for the request, with which the speed of RS-232 can be changed as requirement of equipment. Moreover, module of USB host with USB1.1 protocol can also support the normal full speed USB devices (12Mbps). By considering the reference module of TCP/IP and the character of embedded Ethernet interface, tidy TCP/IP protocol is embedded in MCU and the circuit of network interface is designed with the driver of Ethernet controller being programmed. Thus data transmission for network the between RS232 and USB is realized and its transmitting speed is promoted to 10Mbps maximally. Furthermore, the network application layer of HTTP protocol is implemented which means the data can be transferred through web site.Ethernet interface for device with RS-232 and USB port designed in this paper realizes the net connection of conventional apparatuses and provides the platform of remote monitor and control in industrial field. Testing results illuminate the implement of all functions for the Ethernet interface system.