Omron's sensor FAQ distinguishes PNP and NPN outputs by where the load connects: from sensor output to the negative supply for PNP, and from the positive supply to sensor output for NPN. Check the exact circuit diagrams for the devices in the system.
PNP and NPN describe different transistor output arrangements. Omron’s FAQ explains them by the position of the load in the circuit. The chart below restates that manufacturer explanation; the connection diagrams for the actual sensor and PLC remain the controlling references.
Omron output wiring chart
| Output type | Omron’s load connection description | Before connecting |
|---|---|---|
| NPN | Load between positive supply and sensor output terminal | Match the sensor circuit to the PLC input diagram |
| PNP | Load between sensor output terminal and negative supply | Check polarity, input type and device wiring diagrams |
Omron also notes that its FAQ diagram is a typical example for its E2E sensor family. Other sensor models may use different circuit details. Check the sensor part number, supply voltage, output rating and PLC input documentation before wiring.
This chart describes a wiring distinction, not a complete installation procedure. Have a qualified controls professional review the design where the application requires it.
For sensor selection, see choosing industrial sensors. Browse sensors and vision.
Source
Common questions
Where does Omron place the load for an NPN output?
Omron's FAQ shows the load between the positive supply and sensor output terminal.
Where does Omron place the load for a PNP output?
Omron's FAQ shows the load between sensor output terminal and the negative supply.
Can I choose an output type without checking the PLC?
No. Compare the sensor's output circuit with the PLC input circuit and wiring instructions for the exact models.