Research Of Photoelectrical Smoke Detector Based On Fieldbus

With the improvement of urbanization and density of living environment, hazards of fire on human beings become more serious.People increased awarwness about fire safety and fire alarm system has been widely used. In the promotion of microelectronics and computer technology, fire alarm system has a rapid growth of intelligent,miniaturization and network.In this article, CAN bus is used for data transmission of photoelectrical smoke detector,which is one type of field bus, serial communication network and support distributed,real-time control system. Main features of CAN: high reliability,strong anti-interference ability,support priority arbitration and low cost. SJA1000 and PCA82C250 make up CAN system, which are used for CAN controller and bus driver. The MCU of photoelectrical smoke detector is STC125A60S2, which gain the fire data by collection of signals of smoke and temperature sensor.Fire data is transfered to CAN intelligent adapter by CAN bus and transformed from CAN protocol to RS-232 protocol.Firstly,the article is introduced the basic concepts of CAN bus technology, analysis composition of physical layer and data link layer of CAN,the form of message frame and principle of message filtering. Then, article is introduced the hardware components of SJA1000 important registers of PeliCAN, components of TXFIFO and principle of filtering. The hardware part is the schematic of photoelectrical smoke detector, include connection method between SJA1000 and MCU, composition of photoelectrical smoke detector, selection of temperature sensor and design principles of CAN intelligent adapter. Software part is about the design of CAN system and related code, principles of LabVIEW and the interface of system of monitor.At last, the experiment is designed to test some paraments.Some suggestions of further research is put forward.