The Design And Realization Of Temperature Transmitter Based On The HART Protocol

HART protocol is a communication protocol which used between smart field instruments and equipments in control room. It brings about a compatible transmission of analog and digital signals by superimposing a digital signal on 4-20 mA analog signals, which called FSK. Consequently, instruments with HART protocol can be easily bolted on to the existing DCS system.The main objective of this thesis is to import the micro processing technology and HART communication technology into the temperature transmitter. The transmitter can achieve functions, such as parameters setting, signal compensation, self-diagnosing and et al. with the MCU, while realizing remote configuration, monitoring and calibration with HART technology. Otherwise, this transmitter can achieve the full input, dual channel and multi-line mode, resulting in a more competitive advantage in functions.This thesis first studies the HART protocol, including the physical layer, data link layer and application layer. On this basis,we use MCU MSP430F169 as the control chip to determine the overall architecture. On hardware, mainly consists of the transmitter are sensor, control, data acquisition andprocessing, HART communication, reset circuit, etc.. On software, it includes signal sampling and processing program, display/key interface program and communication interrupt program. On structure, we also select a Shell which matching the size of the circuit board. After the design of the entire transmitter, we also carried on the test to validate the function and practicability of the instrument.This thesis, firstly, studied the HART protocol, including the physical layer, data link layer and application layer. On this basis, we use MCU MSP430F169 as the control chip to determine the overall architecture. Additionally, on hardware, main components of the transmitter are sensors, controls, modes related to data acquisition and processing, HART communication, reset circuit, etc. On software, it was designed to be low-power-consumed, and the primary components include main program, signal sampling and processing program, and communication interrupt program. On structure, we also select a Shell which matches the size of the circuit board.In the end, the thesis gave some improvements like reducing temperature drift, accelerating the speed of sampling, and setting the alarm mode, and test the related functions by software. The result achieved the designed targets.