The Research Of Data Display Instrument For Divided-Into-Segments Liquid Level Measurement

Display instrument has been playing a very important role in the industrial control field. By displaying the major information at the production field, display instrument make people availably monitor and control the production flow. According to the characteristic of petrochemical industry, an instrument which is specially used to display the data of the water height and the oil thickness in the oil tank is designed. The instrument not only can effectively monitor the petrochemical production, but also can greatly reduce the production cost and simplify the production management.After analyzing the features of the divided-into-segments liquid level measurement system and studying the present status of the domestic and overseas display instrument, the general function and the overall design of the instrument are schemed out. Then, the design idea of the hardware and software of the instrument circuit are described. The circuit mainly includes the system power, the system clock, the RS-485 interface, the key and the LED display, the 4-20mA conditioning and A/D conversion, the watchdog and the low voltage detection and the external EEPROM, the warning circuit. Due to the measurement system is distributed and is made up of multiple host devices and multiple slave devices, how to successfully solve the possible communication conflict by introducing a retreat algorithm are expounded. The paper also discusses how to effectively realize the conditioning and A/D conversion of the quadruple 4-20mA when the instrument is in a high noise environment.The instrument is running at the production field by testing, improving and modifying time after time. Because of owning many merits, such as high anti-interference capacity, stable performance and simple manipulation, the instrument has been got the high praise of users and hence has good application value and development prospect.