The Study And Design Of Digital Circuits For The Flowmeter's Conversion Instrument

Electromagnetic flowmeter, which is based on Faraday's induction law, is a velocity-type flowmeter. On the base of analyzing the development status and trend of the electromagnetic flowmeter technology, many advanced technologies are adopted to design the whole hardware and partial software of electromagnetic flowmeter's conversion instrument in this thesis.In the hardware design of the electromagnetic flowmeter, 80C196KC and 80C51 two kinds of MCU are used to control the system. A low-power 12-bit analog-to-digital converter is applied to convert the signal, and the memory space is enlarged by 32×8 bit data RAM CY62256 and 32×8 bit program ROM.128×64 MSC-G12864DYSY is used to display the data and the communication function is realized by RS-485 standard bus. The two systems adopt different methods to realize the logic of circuit, the former uses CPLD and the later uses special IC with logic function. We adopt the alterable wave excitation technology which controlled by the MCU. The PCB was designed under a full consideration of anti-interference.The modular method is applied to design the software of the electromagnetic flowmeter with the 80C196KC and 80C51 MCU C language to control the process of data sampling and displaying. These designs are not only simplified the program structure but also improved reliability and precision of system. Also the emluator of Wave company is used to simulate both hardware and software.Presented results are valuable to the software and hardware design of Electromagnetic flowmeter and also will be beneficial for improving the electromagnetic flow measure technology in our country.