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plc inputs

4 articles tagged “plc inputs”.

Flat vector wiring diagram comparing NPN and PNP sensor connections to a PLC digital input module showing current flow direction for each type
npn vs pnp sensorssensor wiringplc inputs

NPN vs PNP Sensors: Wiring and PLC Connection

NPN and PNP sensors switch current in opposite directions. Get the wrong one for your PLC input card and the signal never works. Here is how to tell them apart and wire each type correctly.

Aug 5, 2026 · 8 min read

Flat vector diagram of a PLC rack showing input module connected to field sensors and output module connected to actuators with signal path arrows through optocouplers
plc i/o modulesplc inputsplc outputs

How PLC Input and Output Modules Work

PLC input and output modules are more than just terminal strips. Learn exactly how signals get conditioned, isolated, and mapped into CPU memory on every scan.

Jul 30, 2026 · 9 min read

Flat vector diagram showing a PLC digital input module connected to a terminal block with a multimeter probing the input terminals to test a PLC input signal
plc troubleshootingplc inputsfault diagnosis

How to Test a PLC Input: Step-by-Step Guide

Learn exactly how to test a PLC digital input, from voltage checks at the terminal to forcing bits in software, with real field-tested steps.

Jul 21, 2026 · 9 min read

PNP and NPN 3-wire sensor wiring diagram to PLC input terminals
sensor wiringplc inputspnp npn

3-Wire Sensor Wiring: PNP vs NPN to PLC Inputs

PNP or NPN sensor, sinking or sourcing input? Learn exactly how to wire 3-wire sensors to any PLC input card with real wiring rules and common mistakes.

Jul 1, 2026 · 9 min read

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