The current output of 4~20mA in the transmitter is a common output form. The output range of current output type transmitters is 4~20mA, and we explained why the conventional current output range is 4~20mA in a previous article. When the current output transmitter outputs the minimum current and the maximum current, it represents the minimum and maximum rated output values calibrated by the current converter, respectively. The following is an example of a current transducer with a measurement range of 0~100A. The output of 4~20mA transmitter corresponds to the input value of 0A with 4mA current. For transmitters with an output of 4~20mA, circuit debugging and data processing are cumbersome. However, this kind of transmitter can be used more widely to determine whether the circuit is faulty and whether the transmitter is damaged by detecting the current within the normal range (the minimum value is 4mA under normal conditions) when the transmitter line is not connected, short circuit, or damaged. The current output type transmitter has the functions of current limiting, voltage limiting and reverse polarity protection. Because when the 4~20mA transmitter outputs 4mA, the voltage on the sampling resistance is not equal to 0, and the digital quantity directly converted by the analog-to-digital conversion circuit is not 0, the single-chip microcomputer cannot be directly used, and the calculation through the formula is too complicated. Therefore, the general method is to eliminate the voltage drop generated by the 4mA on the sampling resistor through a hardware circuit, and then perform an A/D conversion. If you have any questions about product consultation, product customization, agency, technical inquiry, quotation, etc., please contact Xingyi, 400-600-4496!