# PLC digital input

Canonical URL: https://eloragrid.ai/symbols/plc-digital-input
Publisher: Elora Grid
Updated: 2026-10-13
Lookup label: DI
Drawing use: Schematic
Reference families: Manufacturer

A PLC digital input reads a documented discrete electrical state from field wiring.

## What it represents

A PLC digital input reads a documented discrete electrical state from field wiring. The schematic identifies input channel, signal common and field supply as required by the chosen module.

## How to read it

- Check whether the input expects sourcing or sinking field wiring.
- The preview is an original explanation of this function. Match the actual drawing convention to its legend and the selected equipment documentation.

## Information to show or reference

- Identify channel address
- Show input common/supply
- Reference field signal polarity

## Important distinction

A digital input reads a state; it does not provide the power output used to drive an actuator.

## Facts

- Drawing role: Controller interface
- Representation scope: Functional concept; not an official standard graphic or a product footprint
- Identifier status: The short label is a functional lookup label, not an assigned IEC or IEEE symbol number. Any separately listed Autodesk code is a verified vendor block name.

## Public references

- [Modicon TM3 digital I/O hardware guide](https://www.se.com/ca/en/download/document/EIO0000003125/) — Schneider Electric. Public documentation of this equipment function or named vendor variant; the illustration is independently authored and is not the source graphic.

## Graphic scope

Independent original educational concept illustration by Elora Grid. Not a certified standards graphic or manufacturer footprint. Unitless; not to scale. Original artwork licence: https://creativecommons.org/licenses/by/4.0/. Publisher material is linked only.