| Fieldbus has unexampled predominance in reducing cost, improving reliability, and realizing more complex and more exact control. Because along with fieldbus developing rapidly, digital system replacing analog system is a general trend, it's imperative under the situation to digitize the field instrument.So we developed smart electromagnetic flowmeter in accord with HART communication protocol.The paper concretely introduces the essential structure and function of the HART communication port used for the electromagnetic flowmeter in detail and expounds the operational principles in hardware and software. It's based on MSP430 MCU of low power and high performance and solved the most difficult technological problem only with device in hardware. The test proved that it is in accord with the technological criterion of HART communication protocol and it has more performance than cost.With HART communication, smart electromagnetic flowmeter is provided with some functions that general instrument can't implement. It can be connected to control room with a twisted-pair copper cable sharing with other field transducer or instrument so as to predigest design and disposal of cables and reduce cost and malfunction. Especially the computer or control system and read flux and configure the range, zero, units and so on by telecommunication so as to economize manpower and const for maintenance.This paper mainly include:[1] Principles of electromagnetic flowmeter have been studied, flow measuresystem that is based upon HART protocol using MSP430F149 has beendesigned, System circuits has been completed and hardware system has beentested. [2] Principles of digital filter, Cross-correlation method, FFT algorithm have beenanalyzed and applied in experiment. [3] Data transmission based on TCP/IP agreement in industrial Ethernet has beenrealized on vortex flowmeter. |
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