Research And Realization Of Industrial Web Monitoring System Based On ARM

With the continuous development of industrial automation,greater demands are being placed on monitoring system on industrial site.A variety of advanced computer technology,sensor technology and communication technology are appearing on industrial site.Usually,touch screens or computers are used to realize visual monitoring of industrial production lines.This kind of monitoring system based on C/S mode is applied widely.However,some monitoring systems based on B/S mode with unique advantages began to be gradually applied to smart home,telemedicine,agriculture,power systems and other occasions.In this paper,a web monitoring system applied to industrial automation is presented,studied and realized according to practical demands.Firstly,communication network commonly used on industrial site and software model of monitoring system are analyzed,then three kinds of monitoring systems based on B/S mode are analyzed and compared,embedded web server is selected to realize industrial web monitoring system at last.By analyzing the demands of the industrial web monitoring system,it is cleared that functions of monitoring,storage and inquiry of historical data are required to be realized by monitoring system,real-time and security of system also should be taken into consideration.According to the requirements of industrial web monitoring system,overall system program is designed.Related hardware circuits of ARM board of industrial web monitoring system is designed with S3C2440 as the core,including basic function module,storage module and communication module.Then,embedded Linux operating system is transplanted into the ARM board,including Bootloader,Linux kernel and root file system.According to devices which need to be used in motoring system,RS485 driver,DM9000 network card device driver,USB HOST driver and RT3070 Wi-Fi driver are designed and transplanted into embedded Linux system.SQLite database and Boa web server are also be transplanted,and the access of SQLite is realized to store the data collected by RS485 communication into SQLite.In addition,CGI program is designed to realize the connection between Boa server and SQLite database.Historical data has great effect in industrial monitoring system,so data compression algoriths are adopted to deal with historical data based on the consideration of embedded system's limited storage.SDT algorithm and DP algorithm commonly used in lossy compression are compared and analyzed.The SDT algorithm is more suitable for compressing historical data in industrial Web monitoring system.Through the improvement of the SDT algorithm and performance analysis,the improved SDT algorithm compression effect is improved a lot,while the compression time and the average error just grow a little.Finally,algorithms commonly used in lossless compression are analysed and compared,as a result,LZW algorithm has best comprehensive performance and is selected to realize secondary compression of the historical data.Data compression algoriths' application reduces the burden of web server and plays the role of data encryption,the safety of historical data stored in the SD card is guaranteed.Finally,this web monitoring system is applied to steel wire heat treatment production line.MODBUS RTU communication between ARM board and S7-200 PLC is realized.Steel wire heat treatment Web monitoring page is designed to realize on-site monitoring of related equipments and inquiry of historical data and curve.At the same time,Linux multi-threaded technology is adopted to guarantee the real-time of system.Actual operation proves that this system has advantages of stability,flexible structure,and fully meets the requirements of web monitoring.