Liquid level transmitter is an extension and development of pressure transmitter technology, which achieves accurate measurement and transmission of volume, liquid height, and weight of water, oil, and paste based on the principle that the pressure generated by liquids of different densities at different heights is linearly related.

The working principle of a liquid level transmitter is that when two pressures of the measured medium are introduced into the high and low pressure chambers, they act on the δ On both sides of the isolation membrane of the component (i.e. sensitive component), it is transmitted to both sides of the measurement membrane through the isolation membrane and the filling liquid inside the component.

A float level transmitter is a capacitor composed of a measuring diaphragm and electrodes on both sides of the insulation sheet. When the pressure on both sides is inconsistent, it causes displacement of the measuring diaphragm, and its displacement is proportional to the pressure difference, so the capacitance on both sides is not equal. Through oscillation and demodulation, it is converted into a signal proportional to the pressure. The working principle of pressure transmitters and ****** pressure transmitters is the same as that of differential pressure transmitters, except that the low-pressure chamber pressure is either atmospheric pressure or vacuum.

The A/D converter converts the current of the demodulator into a digital signal, and its value is used by the microprocessor to determine the input pressure value. The microprocessor controls the operation of the transmitter. Additionally, it performs sensor linearization. Reset the measurement range. Calculation of engineering unit conversion, damping, square root, sensor fine-tuning, as well as diagnosis and digital communication.

This microprocessor has 16 byte program RAM and three 16 bit counters, one of which performs A/D conversion.

The D/A converter fine tunes the calibrated digital signals from the microprocessor, which can be modified using transmitter software. The data is stored in the EEPROM and remains intact even when power is cut off.

The digital communication line provides a connection interface between the transmitter and external devices (such as the 205 intelligent communicator or a control system using the Hart protocol). This line detects digital signals superimposed on 4-20mA signals and transmits the required information through a loop. The type of communication is frequency shift keying (FSK) technology and is based on the BeII202 standard.