Yes, you can use a PNP sensor instead of an NPN, but only if your control system or PLC input is wired for PNP logic. Both PNP and NPN proximity sensors perform the same job — they detect the presence of an object and send a signal — but they differ in how current flows in the output circuit. Using the wrong type may result in no signal being detected or even cause wiring issues.
A PNP sensor is a sourcing type, meaning when the sensor detects a target, it connects the output to the positive supply (V+). The load or PLC input receives a positive voltage signal when the sensor is active. In contrast, an NPN sensor is a sinking type — when it detects a target, it connects the output to ground (0V), allowing current to flow from the load into the sensor.
If your PLC or controller expects an NPN (sinking input) and you connect a PNP (sourcing output) sensor, the logic will not work because the current flow direction is reversed. However, many modern PLCs support both PNP and NPN wiring — in that case, you can easily switch between the two by changing the input wiring or logic configuration. Always check your controller’s input type before making the change.
In simple terms, you can use a PNP sensor instead of an NPN, but the PLC input type must match the sensor’s output type. PNP sensors are generally preferred in Europe and with Siemens PLCs, while NPN sensors are common in Asian systems. Matching the correct logic ensures reliable detection and safe operation of your proximity sensors in any automation setup.