The thermal resistor temperature transmitter is composed of a reference unit, an R/V conversion unit, a linear circuit, reverse connection protection, current limiting protection, a V/I conversion unit, etc. After the temperature measuring thermal resistor signal is converted and amplified, the linear circuit compensates for the nonlinear relationship between temperature and resistance, and after the V/I conversion circuit, a 4-20mA constant current signal that is linearly related to the measured temperature is output.

  Thermocouple temperature transmitters are generally composed of reference source, cold end compensation, amplifier unit, linearization processing, V/I conversion, broken couple processing, reverse connection protection, current limiting protection and other circuit units. It amplifies the thermoelectric potential generated by the thermocouple through cold end compensation, and then eliminates the nonlinear error between the thermoelectric potential and temperature through a linear circuit, and finally amplifies and converts it into a 4-20mA current output signal. In order to prevent accidents caused by temperature control failure due to thermocouple wire breakage during thermocouple measurement, the transmitter is also equipped with a power-off protection circuit. When the thermocouple wire is broken or the connection is poor, the transmitter will output the maximum value (28mA) to cut off the power supply of the instrument.The integrated temperature transmitter has the advantages of simple structure, saving lead wires, large output signal, strong anti-interference ability, good linearity, simple display instrument, solid module anti-vibration and moisture-proof, reverse connection protection and current limiting protection, reliable operation, etc. The output of the integrated temperature transmitter is a unified 4-20mA signal; it can be used with a microcomputer system or other conventional instruments. It can also be made into an explosion-proof or fire-proof measuring instrument as required by the user.

  Pressure transmitter is also called differential transmitter, which is mainly composed of pressure measuring element sensor, module circuit, display head, case and process connection parts. It can convert the received pressure signal of gas, liquid, etc. into standard current and voltage signal to supply secondary instruments such as indicator alarm, recorder, regulator for measurement, indication and process regulation.

  The measuring principle of the pressure transmitter is: the process pressure and the reference pressure act on the two ends of the integrated silicon pressure sensitive element respectively, and the differential pressure causes the silicon chip to deform (the displacement is very small, only μm level), so that the full dynamic Wheatstone bridge made of semiconductor technology on the silicon chip outputs a mV voltage signal proportional to the pressure under the drive of an external current source. Due to the excellent strength of silicon materials, the linearity and variation index of the output signal are very high. When working, the pressure transmitter converts the measured physical quantity into a mV voltage signal and sends it to a differential amplifier with a high amplification factor that can offset the temperature drift. The amplified signal is converted into a corresponding current signal through voltage-current conversion, and then undergoes nonlinear correction to finally generate a standard current and voltage signal that is linearly corresponding to the input pressure.