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CIRCUIT · RELAY INTERFACE PNP NPN

Relay Interface PNP NPN Circuit Diagrams

Relay interfaces convert PNP sensor signals to NPN outputs (or vice versa) to match PLC input modules and field devices. These circuit diagrams show the wiring, coil, and contact arrangements for common PNP/NPN relay interface applications.

4 EXAMPLES· UPDATED 2026-09-13
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Relay Interface for PLC Input: PNP Sensor Coil Input, NPN Contact Output

ABOUT

About these examples.

Browse examples below for packaging machines, water treatment, motor start-stop, and more. Each diagram is editable — click any example to open it in the editor, modify values, and download or share. Use the generator to start from a blank canvas or adapt an existing diagram.

HOW TO

Make one yourself.

  1. 1

    Choose a relay symbol

    Select a relay coil and contact symbol from the circuit library.

  2. 2

    Add PNP/NPN sensor inputs

    Place PNP sensor blocks for sourcing inputs or NPN for sinking, depending on your PLC input module.

  3. 3

    Wire coil and contacts

    Connect the sensor output to the relay coil, and wire the contact to the PLC input or load.

  4. 4

    Configure ratings

    Set coil voltage, contact current, and terminal labels to match your hardware.

  5. 5

    Export and share

    Download as PNG, SVG, or PDF, or generate a share link for your team.

FAQ

Frequently asked questions

What is the difference between PNP and NPN sensors in a relay interface?01
PNP sensors source current to the load (positive switching), while NPN sensors sink current (negative switching). A relay interface can adapt one type to the other to match PLC input specifications.
How do I wire a PNP sensor to a relay input?02
Connect the PNP sensor output to the relay coil positive terminal, and connect the other coil terminal to ground. The relay contacts then switch the PLC input as needed.
Can I use a relay interface to convert PNP to NPN output?03
Yes, a relay with a PNP-driven coil and NPN-wired contacts can convert a sourcing sensor signal to a sinking output, or vice versa, depending on the contact wiring.
What relay coil voltage should I use for a PLC input?04
The coil voltage depends on the sensor supply and relay specifications. Common values are 24 V DC for industrial PLC systems, but always match the coil to your control voltage.
Can I edit these diagrams to match my exact hardware?05
Absolutely. Every diagram opens in the editor where you can change symbols, wire connections, labels, and ratings to fit your specific relay interface model.
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