Development Of A Temperature Transmitter Based On DeviceNet Fieldbus

Along with continuous development of the fieldbus technology, the design method and technology of intelligent instrument with fieldbus interface is drawing more and more attention. It provided a good opportunity for its fast development since DeviceNet bus entered the national standard in 2003. The purpose of this project is to study the DeviceNet communication specification and the development process of DeviceNet bus product. Considering industrial background, a temperature transmitter with DeviceNet interface is developed based on DeviceNet Rev.2.0 communication specification.The hardware and software design of the intelligent temperature transmitter is presented in this thesis. A single-chip system, mainly using the CAN controller SJA1000, transceiver PCA82C250 from Philips and digital temperature sensor DS18B20 from Dallas, is designed to fulfill basic measurement functions and hardware communication support with fieldbus. The software design consists of two parts, the measurement and communication process. The measurement function involves the data acquisition, display, data processing etc. The communication part presents the implementation of the DeviceNet application layer specification. The designed temperature transmitter, which is based on the design standard of DeviceNet only group 2 slave, is able to gather temperature data , transmit the status information of alarm signal to the DeviceNet network. It is also possible to modify the certain parameters and alarm limitation through DeviceNet network. Thus the temperature transmitter can realize the bidirectional communication of real-time data.This thesis elaborates the design of device with DeviceNet interface based on the singlechip and freestanding CAN controller as well as the development process, including a complete design process from the connection establishment to the object parameter designation and the design result. It provides a nice technical reference for the slave device development.Because the DeviceNet specification hasn't defined the standard description of temperature transmitter yet, a complete device profile for the designed temperature transmitter is designed in the thesis, which strictly follows the specification Rev.2.0. This work has the remarkable value for gradually improving of DeviceNet specification.