高速公路照明用集散控制系统通信网研究

开发了一套功能较完善的高速公路照明用智能集散监控系统，提出了由Internet-Ethernet-RS485光纤网三层网络构建系统的网络通信方案。针对下位机采用基于RS485通信协议的可编程控制器（PLC），分析了联网拓展的可行性，构建了新拓展的PLC RS485网络通信系统，使PLC网络通信系统可同时接入多达256台的PLC。试验运行结果表明：系统性能稳定，实现了高速公路照明系统的远距离集中智能监控。

Investigation on a New Communication Network of DCS for Highway Lighting Monitoring System

Based on the model of three layers Internet-Ethernet- RS485 network,a DCS system developed for monitoring and control of highway lighting monitoring system(HLMS) is presented,which is composed of proxy server, SQL server .industrial computers ,and FX2N PLCs made by MITSUBISH ELECTRONIC. When this kind of PLC as the substation and RS485 communication protocol are utilized, the disadvantage of the corresponding RS485 network is that the only 16 PLCs can be linked together to work based on RS485 communication protocol. In order to extend the number of PLCs,an optical fiber communication network is introduced and investigated. As a result,256 PLCs can operate together instead of 16 PLCs based on RS485 communication protocol. Applied and tested in the HLMS,the new communication network shows high performance such as high reliability with lower price.