1 The proximity switch has two-wire system and three-line system of difference, the wire close switch is divided into NPN and PNP type, their wiring is different. See the image below:
2 The wiring of the two-wire proximity switch is simpler, and the proximity switch and the load are connected to the power supply.
3 three-wire system close to the switch wiring: red (brown) line connection power supply, Blue Line connection power supply 0V end, yellow (black) line for signal, bell load. The other end of the load is this: for the NPN type proximity switch, it should be connected to the power supply, and the PnP-type proximity switch should be connected to the 0V end of the power supply.
4 The load of proximity switch can be the digital input module of signal lamp, relay coil or PLC of programmable controller.
5 Special attention to the PLC digital input module of the three-wire system close to the switch type selection. PLC Digital input modules can generally be divided into two categories: a type of public input terminal is the power supply cathode, the current from the input module outflow, at this point, must choose NPN type proximity switch, the other type of public input is the power supply cathode, current into the input module, at this time, must choose PNP type Proximity switch. Don't make the wrong choice.
6 The two-wire system close to the switch is limited by the working conditions, when the switch itself produces a certain pressure drop, the cut-off and a certain residual current flow through the selection should be considered. The three-wire proximity switch, although more than one line, but not by the residual current and other adverse factors, the work more reliable.
7 Some manufacturers will be close to the switch "often open" and "often closed" signals at the same time, or add other functions, this situation, please follow the product specification specific wiring.