Proximity switch is a position switch that can be operated without direct mechanical contact with moving parts. When an object approaches the distance from the sensing surface of the switch to the action, the switch can be started without mechanical contact and any pressure, so as to drive DC appliances or provide control instructions to computer (plc) equipment. Proximity switch is a kind of switch-type sensor (i.e. contactless switch), which has the characteristics of travel switch and microswitch. It has good sensing performance, reliable action, stable performance, fast frequency response, long service life, strong anti-interference ability, waterproof, shockproof and corrosion resistance. Products include inductance, capacitance, Hall, AC and DC.

Proximity switch, also called contactless proximity switch, is an ideal electronic switch sensor. When the metal detector is close to the induction area of the switch, the switch can send out electrical instructions quickly, without contact, pressure and sparks, and accurately reflect the position and stroke of the moving mechanism. Even if it is used for general travel control, its positioning accuracy, working frequency, service life, convenience of installation and adjustment and adaptability to harsh environment are incomparable to general mechanical travel switches. Widely used in machine tools, metallurgy, chemical industry, textile, printing and other industries. It can be used as limit, counting, positioning control and automatic protection in automatic control system.

Common wiring diagram of proximity switch:

? Bk (black) black: generally, it is the output line, and the output is always on.

Bn (Brown) Brown: Generally, it is the power cord connected to the positive pole of the power supply.

Bu (blue) Blue: Generally, it is the power cord, which is connected to the negative pole of the power supply.

Wh(white) white: generally, it is an output line, and the output is normally closed.

Npn: Black terminal is connected to the load, and the other end of the load is connected to the positive pole of the power supply.

Pnp: The black end is connected to the load, and the other end of the load is connected to the negative pole of the power supply. )