Intelligent Pressure Transmitter Based On HART Protocol

Following the swift development of science and technology and the continuous progress of society, rock oil, chemical plan, metallurgy etc have increasing demands to the level and the extent of controlling of automation and put forward the higher demand to various meters of this field in capacity, precise, function and reliability. Rapid developments of information technologies have made instruments, such as sensors and transmitters develop in higher precision and reliability, and also in automation, multi-function and intelligence. The field Bus is a technique, which could take a great role and therefore a rapid development in the revolution of industrial measurements and automatic systems. Smart transmitter is a typical intelligent instrument in which integrated with the Sensor and the communication system. Compared to general the conventional analogue transmitter, the intelligent transmitter has not only higher precision, better reliability and stability, but also the real-time characteristics and intelligence. It can be widely applied in scientific measurements and industrial automations, and so has the paramount importance for researching and developing.Field Bus is hot topic in automatic detection field nowadays, which is an opening, digital and multi-drop communication control network of low layer. The development of full-digital system in Field Bus is a general trend. However, 4--20mA analog signal instruments also have a large application in industry, the HART communication protocol--a transitional protocol during transition from analog system to digital system—emerges as the times require. Based on Bell 202 communication standards, HART protocols transfer data with different frequency signals and plus with 4～20mA of analog signals.Being based upon HART protocol, this paper combines the MCU and sensor to an intelligent transmitter. Firstly, the detailed the hardware analysis and designs are introduced, including the single-chip microcomputer, the sensor module, the communications module and AID,X D/A module; Then, the structures of the software are analyzed and designed.