Can Bus Based Design Of Building Automation System

With the rapid development of national economy and the broad application of computer technology, communication technology, audio&video technology, the intelligent building has been developed with high speed, in which the building automation system is the key factor to realize the target stated above. The Fieldbus control system can handle the problem caused by the closed system with specific network communication in the distributed control system, which has realized the multi-function of integrative automation with converting the closed and specific based solving scheme to the open and standardited one. CAN bus has a broad application foreground.The research is finished with the help of the scientific research item in the paper according to the government office block in Shandong province, the CAN bus based on the building automation system is designed. The concepts and development of the intelligent building and the building automation system are introduced firstly, and the CAN bus is regarded as the communication bus in the control system through comparing of the following buses: fieldbus foundation(FF), process fieldbus(PROFIBUS), local operating networks(LONWORKS), highway addressable remote transducer(HART) and control area network(CAN). After researching on CAN bus technology criterion, the function and operating principle of CAN bus control SJA1000 and the bus dirver 82C250, the CAN bus based fieldbus control system is designed, the whole hardware circuit designs of temperature test control and power-cut alarm intelligent nodes are presented and the main program flow charts of the control nodes are proposed. The median filtering algorithm is proposed to improve the data acquisition precision. The method of time division multiplexing and the information scheduling scheme of PIR promoting are presented to improve the real-time character of the CAN bus system. The simulation experiment is done to verify the temperature control algorithm in MATLAB for there are so many temperature control nodes, the result show that the algorithm is feasible.