Profibus-dp Protocol Analysis And Software Implementation

Fieldbus technology has been produced since the 70's and cause widespread concern. The market has developed rapidly, leading to a revolution in the field of automatic control. PROFIBUS (Process Fieldbus) is an international, opened fieldbus standard. PROFIBUS-DP (Decentralized Periphery) which is belong to PROFIBUS technology is the most widely used, represents the essence and characteristics."R & D of new electronic belt scale control instruments" project reduce costs and improve accuracy as well as development. The project appply the new dsPIC (Digital Signal Controllers) to control the instrument as the core of the new electronic belt scale computing processing unit. We adopt AD7730 (24-bit ADC chip) to deal with the output analog signals of sensor and transform the analog signal into digital signal. then transmit it into dsPIC. In order to achieve its direction of the intelligence, we have to make the host machine's PLC understand the next-bit machine called t electronic belt scale data. Similarly the lower computer electronic belt scale have to understand the host machine's PLC status. They need a communication mechanism to interact with information. Our station is siemens PLC which often uses the bus to control the system , to join the system to accept the PLC control, we set electronic belt scale as a DP standing on the dp profibus - bus. If we use the ASIC method we should adjust the structure of the chip, we even should change the CPU, and the plan is impracticable. So, we use programmatic scenarios to implement communication between the PLC and electronic.This paper's goal is to an analyse PROFIBUS-DP protocol and make experiments with our available equipment based on "control instrumentation research and development of new electronic belt scale" project. We introduce the operational principle of PROFIBUS-DP slave station, the formats of data transmission, configuration of profile and GSD file and other relevantly information. Then we give the operation of hardware configuration process, precautions, and various parts of the packet number of the significance of light signals through the PLC fault state, verify the correctness of the communication combined SIMATICS7-300. We have realized communication between PLC and electronic belt scale. The system we designed can work under the five baud rate with 1.5Mbps'maximum data transfer rate. And this result have met the requirements of industry. We should further improve the competitiveness of electronic belt scale, design accuracy and function improve so that we can meet the needs of users.