被 测介质的两种压力通入高、低两压力室，作用在敏感元件的两侧隔离膜片上，通过隔离片和元件内的填充液传送到测量膜片两侧。 The two pressures of the measured medium of the pressure transmitter pass into the high and low pressure chambers, and act on the isolation diaphragms on both sides of the sensitive element, and are transmitted to both sides of the measurement diaphragm through the isolation diaphragm and the filling liquid in the element. The measuring diaphragm and the electrodes on the insulating sheets on both sides constitute a capacitor.
样的 时 侯 ， 会 使 得 测量膜片产生位移，其位移量和压力差成正比， 所以 两侧电容量就不等，通过振荡和解调环节，转换成与压力成正比的信号。 When the pressure on the two sides is different , the measurement diaphragm will be displaced, and the displacement is proportional to the pressure difference, so the capacitance on the two sides will be different . Through the oscillation and demodulation links, it will be converted to the pressure. Proportional signal. 和绝 对压力变送器 的工作原理和差压变送器相同，所不同的是低压室压力是大气压或 者 真空。 The working principle of pressure transmitters and absolute pressure transmitters is the same as that of differential pressure transmitters, except that the pressure in the low-pressure chamber is atmospheric or vacuum.
This microprocessor has 16 bytes of program RAM and three 16 -bit counters, one of which performs A / D conversion.
， 微处理器控制变送器的工作。 The A / D converter converts the current of the demodulator into a digital signal. Its value is used by the microprocessor to determine the input pressure value . The microprocessor controls the operation of the transmitter . , 重 新设 置测量范围。 In addition, it linearizes the sensor and resets the measurement range. ， 开方，传感器微调等运算，以及诊断和数字通信。 Engineering unit conversion , calculation , sensor fine-tuning and other operations, as well as diagnostics and digital communication.
The D / A converter fine-tunes the data from the microprocessor and the corrected digital signal. These data can be modified by the transmitter software. The data is stored in the EEPROM , and it is stored intact even if the power is off.
比 如275 型智能通信器或 者 采用HART 协议的控制系统 ) 的连接接口。 The digital communication line provides the transmitter with a connection interface to external devices ( such as a Model 275 intelligent communicator or a control system using the HART protocol ) . This line detects the digital signal superimposed on the 4-20mA signal and transmits the required information through the loop. The type of communication is frequency shift keying FSK technology and is based on the BeII202 standard.