Development And Application Of RTU In Granary Situation Observation System

The grain storage is very important to food supplies and food security. In the work of grain storage, the part of remote observation in granary is proven significant.The article has researched the development and application of RTU in the granary-situation observation system.With the communication carrier of mobile network and Internet , the hardware integrated and software designed is completed and the algorithm of encryption in data communication is researchedThe article introduces the research background and significance, points out that the granary-situation observation system is important to grain storage work;Then analyze the excellence of GPRS communication by contrast in several communication styles.Hance in the hardware integrated ,the Rabbit processor choosed because of the low power consumption, the excellent cost performance, and the support to TCP/IP protocol and the wireless module selected which support GPRS protocol can content the GPRS/Internet communication between RTU and upper computer.Meanwhile the function entitys in the granary connect each other using a emerging technology named ZigBee instead of bus which can make net connecting conveniently under RTU. At last the observation system of RTU and ZigBee is integrated and achieved.The article designs the communication protocol.Firstly the uC/OS-II real time operation system and the Dynamic C software are choosed due to its good compatibility with Rabbit processor,which the communication protocol is designed in the basis of it.Then communication data structure and communication protocol of RTU are devised,especially the data sending , data receiving and network connecting.The primary functions of the communication protocol is to send data to upper computer on time or send data and set parameter according to orders from upper computer. After the field testing, the protocol can fulfil the prospective mission and can content the basic communication requirement, at last the test procedure of communication protocol is given by chart.Considering the unsafe factors in the GPRS and Internet, we have to encrypt the communication data. According to the category of network attacks and the analysis in cryptography, we take into account these three issues: confidentiality, integrality, authentication, and integrate the three to one called composite encryption arithmetics .Owing to the slow encryption speed, the article modify the composite encryption arithmetics using secret sequence to substitute the authentication of RSA.The arithmetic is implemented in the fashion of software in Peer-to-Peer style with compilation in Dynamic C,and the chart of communication in encryption function is given in the end.