Side-by-side reference

Understand the difference.

Compare the meaning, drawing context and source references of two entries. A similar graphic or shared abbreviation does not establish equivalence.

First referenceCompare with

LS NO

Symbols

Normally-open limit switch

A normally-open limit switch closes when the documented mechanical travel or position condition actuates it. It identifies a position input rather than the complete mechanical arrangement.

Drawing use: Schematic
Application: Control circuits
Reference family: IEC / Manufacturer

A distinction that matters

A limit switch responds to mechanical position; a pushbutton responds to an operator action.

Full reference

PLC I/O

Symbols

PLC input / output

A PLC input or output point connects a field signal with a controller module and channel. Input and output, digital and analogue, and one-wire or multi-wire arrangements are distinct characteristics. The module specification establishes electrical behaviour and terminal information.

Drawing use: Schematic
Application: Control circuits
Reference family: IEC / IEEE / ANSI

A distinction that matters

An input point, output point and communications connection are different interfaces. A generic box cannot establish their electrical compatibility.

Full reference

Original educational previews. Follow the source references on each full entry for the appropriate standard or selected product.