Research On Real-time Performance Of An Embedded Web Server

The technology of EWS (Embedded Web Server) applies widely in the industrial monitoring system and process control system. Industrial embedded System is real-time system, so the EWS must be the real-time system too. EWS, which designed in the single chip, doesn't have embedded real-time operating system and use the CGI (Common Gateway Interface) to realize the simple monitoring by network, so it can only realize simple internet monitoring. While the intellectual instrument's capacity of monitoring and configuration, the designing method of using the server's microprocessor source to draw and communicate the huge digit is not satisfied the real-time requirement of industrial instrument.To this question, the paper researches the critical factors of real-time performance and brings forward the designing scheme in the platform of 32 bit microprocessor AT9140008 according to the C3000 controller. Server uses the μC/OS-II real-time operating system and LwIP protocol stack and adopts the multithreading method to improve the real-time. According to void-paper peculiarity, we utilize the ActiveX technique with the B/S (Browser/Server) and C/S (Client/Server) modes design the client interface. The software downloads to the client computer and draws and refreshes the interface by the client source instead of the server source. In the industrial Ethernet, the server realizes the certain Ethernet transfer by the EPA protocol which can improve the real-time property.The real-time responding time of industrial system is less than 4-10ms, and the interval time between of two packs will sending of the C3000 is 0.125s. In the result of the software testing, the responding time of the ping is 0.4ms, and the responding time of HTTP is 4ms, the interval time between of two packs will sending is 0.025s, and the refurbishing speed of the web interface is the same as instrument's. From the results above, they can improve that this designing method can satisfy the real-time and stability of industrial instrumental internet monitoring system.First, the paper studies three factors influencing the embedded web server real-time property. They are hardware, software and networks. According to the factors, the paper makes sure the scheme, and introduces the designing tools. Then, paper depicts the replant of μC/OS-II real-time operating system and lean TCP/IP protocol stack LwIP, HTTP server with file systems, digit communication and Ethernet driver, and test the performance of server. And then, according to peculiarity of void-paper, paper design the monitoring interface, which is composed of memory module, network communication module, real-time monitoring module, history monitoring module and so. At the end, paper summarizes the work and makes a prospect.