First of all, attach a wiring diagram:

The specific connection method is:

1. The npn photoelectric switch is connected to the sink input mode. Connect the switch output terminal ( ) of the proximity switch to the input terminal of the plc, and the other terminal (-) of the proximity switch to the com terminal of the plc.

2. If the pnp proximity switch is connected to source input, then the 24v terminal of the plc should be connected to the negative pole of the external power supply, the positive pole of the external power supply is close to the ( ) terminal of the switch, and the other end of the proximity switch (-) is connected to the input terminal of the plc.

1. Photoelectric switch (photoelectric sensor) is the abbreviation of photoelectric proximity switch. It uses the object to be detected to block or reflect the light beam, and connects the circuit through the synchronization loop to detect the presence of the object. Objects are not limited to metal, all objects that can reflect light (or block light) can be detected.

2. The photoelectric switch converts the input current into a light signal on the transmitter and emits it, and the receiver detects the target object based on the intensity or presence of the received light. Photoelectric switch smoke alarms are common in security systems and are often used in industry to count the number of movements of robotic arms.