The pressure sensor power is 24V, the current signal is 4-20MA, (the 2 wire pressure sensor as a negative I) on the instrument are set up, why in the connection time, to get a line receiving instrument display box power output is above 24V cathode, a cathode box above the receiving instrument display 4-24MA, then they are connected by a wire electrode, what is the principle, thank you, heroes pointing trouble!!!
When 24V, the input power box also needs the power supply, and the zero line can be connected together
See map, 24V DC power supply, the pressure sensor (transmitter), digital instrument is actually a series circuit, digital display table after the set is equivalent to a current meter, just put the current into the corresponding pressure display. The transmitter is equivalent to a resistor. When the pressure changes, the resistance changes accordingly, and the current in the circuit changes accordingly, so the meter shows the corresponding pressure.In fact, intelligent digital instrument in general have 4-20MA terminal comprises a 24V power supply, can be directly connected with the sensor is connected to the negative is negative, then, the circuit is relatively simple.
