The Design And Implementation Of The Embedded Network Device

Along with the extensive application of embedded system, connecting embedded devices to Internet will become a kind of necessity. Once embedded system is equipped with network interface, and supported by TCP/IP protocol suite, it may access to Internet. In industrial control field, intelligent equipments, instruments, appearances and sensors show a tendency to convert into "Embedded Network Devices".The Embedded Network Device researched in this paper is a distributed I/O device which has an ethernet interface,it is applied mainly in industrial automatic control field. It is composed of NetController module and Distributed I/O modules. On the one hand, the NetController supports network transmission by the embedded Web Server, and offers network monitoring function in the system; On the other hand, it communicates with the Distributed I/O modules on RS485 Network, parses the data uploaded from the Distributed I/O modules and disposes it according to regular protocol. The Distributed I/O modules complete the acquisition of the analog and digital signals on-the-spot as well as carry out control to the implement. User may form a supervisor system which is large or small according to the demand from a few to hundreds of points. This system is a distributed I/O system which realizes supervisor and control function via WebBrowser conveniently. So, its compatibility and reliability are much rather than other system.The project have adopted 32-bit ARM7TDMI RISC Processor and Ethernet Network Interface Controller which build up a network hardware development platform, realizing the network part of the Embedded Network Devices; The system uses MCS-51 SCM as the processors of Distributed I/O modules which are developped in series and may meet the requirement of measure and control front in most industrial scene. Net_Controller module and Distributed I/O modules build up a RS485 Network which contains a single master and multi-slavers. Because the embedded operation system(NET+OS) selectted support network protocol well, we can realize following protocols ARP, IP, ICMP, TCP and HTTP application protocol in the conveniently.The Embedded Network Device supported by the protocols above-mentioned can provide WWW service for PC on Internet, the users on network can access to the embedded web on standard browser. Therefore, it has realized remote supervisor and control and trouble diagnosis function for the equipments on-the-spot.