Research On Intelligent Temperature Transmitter Basis On PROFIBUS PA BUS Protocol

With the rapid development of modern industries,filed bus is indispensable now. Due to its two-wire power for filed instrument and digital communication,which canapply for intrinsic area,so it got widely used.The system based intelligent temperature transmitter, add to PROFIBUS PA bus communication,which integrated digital communication for temperature transmitter,Improve automation level and EMC compatible.The system consist of two part,one is PROFIBUS PA protocol communication,the other is intelligent temperature transmitter。The communication and temperature detect is finished by a CPU,which reduce complex of programming.The ASIC SIM1 and SPC4 is used as the core of PROFIBUS PA system to modulate and demodulate Manchester code, which can interpret link protocol also. The microcontroller made by MITSUBISHI company is used as data processing, which has open bus interface,more powerful on anti-interference,performance stable in actual conditions.The communication card and transmitters of PROFIBUS PA instrument were designed respectively in traditional, the communication between bus and transmitters is achieved by isolated driven. The system combine bus function with transmitters, the microcontroller M30626 is responsible for data transmission and signal detecting of temperature sensor. Analog signal convert to digital signal of input signal by 24-BIT AD converter ADS1248.The system utilized auto calibrating technical of intelligent temperature transmitters,improving production efficiency to a great extent for temperature transmitters of filed bus type.In the embedded worktable-IAR Embedded Workbench,C language is used to complete controlling and data traffic, which achieving the necessary measurement flow of industry automatic instruments. Using C language for programming can improve work efficiency greatly, improve the reliability readability and replanted of the program, and it is convenient to continue perfecting, and extending the design.The temperature transmitters of PROFIBUS PA applied in the thesis has adopted special IC to transmit data which ensure high reliability and has used the low power loss and fast computing ability of microcontroller to accomplish the stability of systemcontrolling and manage. Improving production efficiency to a extent for temperature transmitters,realized thesisˊ wishes.After more than a year of exploration and research, and a lot of experiments and test,the intelligent temperature transmitters of PROFIBUS PA protocol can meet the requirements of production customers and applied in the industry field. After correct fixing, checkout, adjusting and setting locale parameter accurately,PA bus can read、write parameter of temperature transmitters.