1) The proximity sensor has 2 wire system or 3 wire system, of which 3 wire proximity sensor is divided into NPN type and PNP type, and their connection methods are different. Please see the following figure:

2) The connection of the 2 wire system proximity sensor is simple. One can first connect the proximity sensor and the load, then connect them with the power supply.

3) The connection of the 3-wire system proximity sensor: the red (brown) line is connected to the positive end of the power supply; the blue line is connected to the 0V end of the power supply; the yellow (black) line is the signal and should be connected to the load. The other end of the load is connected as such: for the NPN proximity sensor, it should be connected to the positive end of the power supply; For the PNP type proximity sensor, it should be connected to the 0V end of the power supply.

4) The load of the proximity sensor can be signal light, relay coil or PLC digital input module.

5) Special attention should be paid to the type selection of the 3-wire system proximity sensor which is connected to the PLC digital input module. The digital input module can generally be divided into two categories: one type of common input terminal is the positive pole of the power supply, and the current flows out from the input module where the NPN proximity sensor must be used; the other type of common input terminal is the negative pole of the power supply and the current flows into the input module. At this time, the PNP proximity sensor must be selected. Please don’t make the wrong choice.

6) Restricted by working conditions, the 2 wire proximity sensor produces a certain voltage drop when it is on, and a certain amount of residual current when it is off, which should be taken into account when one selects it. Although there is one additional line in the 3 wire proximity sensor, free from the remaining current and other adverse factors, the work is more reliable.

7) Some manufacturers extract the sensor "often open" and "often closed" signal at the same time, or add other functions. On this situation, please follow the product instructions for specific connection.