Research On Intelligent Flow Measure Instrument&System Based On LonWorks Bus

Flow measurement is widely applied in agriculture, national defence, science research and our life.In recent years, people have paid much more attention to the accuracy of flow measurement as technology progresses.The intelligent flow totalizer system in this design is combined with the spindle flowmeter, the embedded system techniques and Lonworks bus.During the period of measurement, the transduction circuits transform the differential pressures, the absolute pressures and the temperature received by the sensors into the voltage signals. The MCU named P89C51RD2 as the main controller transforms the voltage signals into digital signals by controlling A/D convertor. Because differential pressures directly influence the result of flow measurement, three temperature compensations are researched in this paper. The temperature compensation experiment is carried out. The compensation results are analyzed and compared. The MCU processes these digital signals and cumulate the flow quantities according to interrelated formula. During the flow calculating, density compensation is researched. Sevaral parameters are displayed in LCD by key-press controlling.In the communication module, flow measurement system connects with PC by Lonworks bus. The MCU can transmit the parameter to PC real-time. PC can process and watch the change of these parameters.Demarcate experiment about flow coefficient is carried out in laboratory.