Signals & Electrical
Digital input
An input that normally recognises just two states.
IN ONE SENTENCE
It tells a controller whether something is ON or OFF, true or false.
In normal English
Digital inputs are used for switches, proximity sensors, relay contacts and status signals. The electrical details still matter: voltage, PNP/NPN and wet/dry contact must match.
Why would I use it?
Use it for simple states such as tank full, door open, motor running or alarm active.
THINK OF IT LIKE…
A yes/no question asked by the control system.
Related terms
digital output, PNP, NPN, volt-free contact
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