The 224 series temperature and humidity transmitter is a type of transmitter for measuring humidity without display, which includes a humidity sensor and a signal conversion circuit. The humidity sensor is used to sense humidity in the environment, and the signal conversion circuit converts the signal of the humidity sensor into a standard current signal or standard voltage signal, as well as a 485 signal. After the processing of the conversion circuit, the signal of the humidity sensor is converted into a current signal or a voltage signal that is linearly related to humidity, and these signals can be read and processed by other devices. When using a humidity transmitter, it is necessary to pay attention to the correctness of the power supply voltage and the distance between the transmitter and the collector to avoid signal disturbance. Meanwhile, selecting the appropriate output form based on accuracy requirements is also very important.