Research And Realization Of RTU Networking Based On LwIP Protocol Stack

Remote Terminal Unit is one important part of the automatic control system. RTU is responsible for field data collection, storage, and real-time communication with the host computer, it is suitable for severe working environment. If RTU access the Internet through Ethernet, the information and the correctness of the work can be collected at any times and places. Finally, it can achieve the real-time monitoring to field data. According to the TCP/IP protocol stack and the background of oil field, LwIP protocol was selected to achieve network communication based on Internet between the RTU and the host computer which is suitable for embedded applications.The thesis analyzes IP protocol, ICMP protocol, TCP protocol, UDP protocol and several key modules of the LwIP protocol stack, and selectes μC/OS-Ⅱ which is a open-source, real-time embedded operating system as the platform of LwIP. LwIP protocol will be transplanted to μC/OS-Ⅱ in order to achieve Internet communication between the RTU and the host computer.In order to verify network communication between the RTU and the host computer based on LwIP protocol directly, HTTP protocol will be achieved in the application layer. Host computer visits RTU by the IP address and exchange data with the RTU. Finally, it will monitor and access RTU intuitively through the web page.The results of the test show that the system runs stably and the communication between host computer and RTU is normal. As the background of remote monitoring system in oil field and the special environment, the realization of RTU networking based on LwIP protocol will show its application value and can be improved according to the practical requirements.