A programmable universal capacitive liquid level sensor controller and its control method

Abstract

The invention discloses a programmable universal capacitance type liquid level sensing controller and a control method thereof, and relates to the technical field of sensor control.The controller comprises an excitation circuit of a sensor, a detection circuit, an analog-digital conversion module and a microprocessor module.The controller has the advantages that by means of programmable control, the sensor can meet various measurement conditions to obtain a richer and more precise measurement result; calibration is support and a calibration value is automatically loaded, so user operation is more convenient and efficient; in an active shielding mode, the stray capacitance of a measurement circuit is eliminated, and measurement precision is improved; detection of liquid levels in a needle and a container is supported; by means of the differential integral digital algorithm, the stable detection result is obtained, and rich result output and display are supported; logic condition prejudgment in a microprocessor is made, output of four gears of digital levels can be supported, result indication can be achieved through four gears of LEDs, the measurement result can be displayed in the form of a graph through an upper computer, and good human-computer interaction is achieved; abundant communication interfaces exist, UART\RS485\CAN and other control interfaces are supported, and the upper computer can select any interface for connection control.

Description

technical field [0001] The invention relates to the technical field of sensor control, in particular to a general capacitive liquid level sensor controller and a control method thereof. technical background [0002] Capacitive liquid level sensors are widely used due to their low price, simple structure, good dynamic response, not easy to damage, stable operation and ability to work in extremely harsh measurement environments such as high temperature, deep cold, radiation and strong vibration. It is widely used in liquid level measurement in modern petroleum, chemical, food, pharmaceutical, medical and other fields. But at the same time, capacitive sensors in capacitive liquid level juice generally have shortcomings such as poor load capacity, difficult to handle measurement signals, and high output impedance, mainly because the capacitance of the capacitive sensor itself is only tens to hundreds of picofarads, which is vulnerable to stray capacitance and temperature effect...

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Problems solved by technology

[0010] The notification number is CN101692005, and the invention patent named "digital capacitive liquid level measurement sensor" is a digital capacitive liquid level measurement, but the capacitive probe of the device is processed by MEMS technology, and the cost is relatively high. The device uses CDC Conversion chip AD7746, the chip is an imported chip, the price is more expensive

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