Intelligent Temperature Transmitter Based On Fieldbus Thchnology

By placing the microcontrollers into the traditional instruments, Fieldbus technology enables those measuring and controlling instruments to get the ability of digital calculation and communication and become the network nodes which can independently accomplish the functions of detecting, controlling and communicating. Compared with DCS, FCS realizes intercommunication between control stations and field equipments and absolutely 'distributed Control' . It is the development trend of autocontrol system, which becomes one of the important research hotspots in the autocontrol system field in recent years. CAN-bus is a kind of fieldbus. It has remarkable advantages such as simple structure, fine real-time quality, high reliability, powerful anti-interference ability, low cost and strong flexibility. CAN-bus is the only field bus with international standard at present.The thesis analyzes and studies the CAN-bus technology. We adopt microcontroller MC9S12DJ128 with CAN interface made by Freescale and the (dedicated) temperature signal processing chip MAX6675 to constitute the whole system. Using the K thermocouple as the temperature sensor, we develop the temperature sensor which applies CAN bus.The paper consists of five parts:The first chapter is the introduction. This paper discusses the meaning of the subject, the relevant research on current situations and our research scheme. Besides, the relevant documents and materials are summarized in this part.The second chapter details the structure and characteristics of CAN-bus and analyses the development trend of CAN-bus in term of application.The third and the forth chapter is the emphases of the paper. It details the hardware design and software design of the whole system. It mainly includes the hardware and software design of temperature measuring module, alarming module, displaying module, supplying module and CAN communication interface module and so on.