IKSACE E3Z-R61 Photoelectric Beam Sensor Indoor Wall Mounted NPN -NO Or NC Switchable- Retroreflective photoelectric Sensor Proximity Switch with 2M Cable Reflector Panel Pack of 2

Explanation on the definition of NO, NC, NPN, PNP: NO(Normally open): the circuit is open when there is no sensing object, and the circuit is closed after sensing the object NC(Normally closed): the circuit is closed when there is no sensing object, and the circuit is open after sensing the object NPN: Taking 24V voltage as an example, the output voltage is 0V when sensing objects, and the output voltage is 24V when not sensing. NPN: Taking 24V voltage as an example, the output voltage is 24V when sensing an object, and the output voltage is 0V when not sensing. Sensing object: non-transparent object