PNP and NPN type outputs are available as 3-wire sensors with a DC voltage power supply (the voltage limits are dependent on the specific sensor):

PNP type: switching on the positive voltage load

NPN type: switching on the negative voltage load

These outputs are typical of photoelectric detectors, inductive proximity and other types of sensors.

For a detailed explanation of PNP vs NPN, see the following FAQ: FA142566

PNP output

The load (relay coil, contactor relay input, PLC input) must be connected between the "-" negative terminal and the midpoint.

The corresponding PLC input is Sink.

NPN output

The load must be connected between the "+" positive terminal and the midpoint.

The corresponding PLC input is Source.

Some sensors have two PNP and NPN outputs (4-wire sensors) which are wired according to the diagram below.



Note that wiring diagrams can be found on the instructions provided with / for a sensor, or in the catalogue. All this documentation is found online at www.se.com or www.tesensors.com