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The working principle of Ross Mont transmitter
Jan 16, 2018


Ross Monte transmitter is the most commonly used sensor in industrial applications. It is widely used in many industries, such as water conservancy and hydropower, railway transportation, intelligent building, production automation, aerospace, military industry, petrochemical, oil well, electric power, ship, machine tool, pipeline and many other industries.

The Ross Mont transmitter is used to measure the level, density, and pressure of liquid, gas, or steam, and then change the pressure signal to 4-20mADC signal output. There are mainly capacitive pressure transmitters and dispersed silicon pressure transmitters, ceramic pressure transmitters, strain pressure transmitter and so on.

Direct effect on the pressure sensitive diaphragm, Wheatstone bridge resistor which spread on the sensitive diaphragm on the piezoresistive effect, use gas to realize the pressure signal transform, millivolt signal through the electronic circuit will occur as the sensitive element industrial standard signal amplification.


The two pressure of the pressure transmitter is measured into the high and low two pressure chambers. It acts on the sides of the diaphragm on the two sides of the delta element (sensitive element), and passes through the filling fluid in the barrier and components to measure the sides of the diaphragm. Measurement of the diaphragm and the electrodes on both sides of the insulating sheet constitutes a capacitor. When the pressure on the two sides is not consistent, the displacement of the diaphragm is caused. The displacement is directly proportional to the pressure difference, so the capacitance on both sides is not equal. After vibration and demodulation, the signal is directly proportional to the pressure. The operation principle of the pressure transmitter and the positive pressure transmitter is the same as the differential pressure transmitter. What is not the same thing is that the pressure in the low pressure chamber is the atmospheric pressure or the vacuum.

The A/D converter transforms the current of the demodulator into a digital signal, and its value is used to determine the input pressure value by the microprocessor. The operation of a microprocessor manipulating the transmitter. In addition, it linearized the sensor. Reset the measurement scale. Engineering unit conversion, damping, prescribing, sensor trim and other operations, as well as the diagnosis and digital communication.

The D/A converter fine-tuning the data from the microprocessor and the corrected digital signals, which can be modified by the transmitter software. The data is stored in EEPROM, even if the power is broken. A digital communication line provides a connecting interface to a transmitter for an external device (such as a 275 type intelligent communication device or a control system using the HART protocol). The circuit checks the digital signals superimposed on the 4-20mA signal and sends the required information through the loop. The type of communication is the transplant keying FSK skills and according to the BeII202 specification.