Industrial Engineer · phase 4 of 16 · noun

Structure / UDT

Grouped data type that combines related members under one name.

The Explain card

Plain English: A user defined type bundles related values under one name. A motor structure might hold its run command, its running feedback, its fault bit, its current and its hours, and every motor tag is one of those.
Example: Pump3 is a Motor UDT. Its run command, running feedback and fault bit all travel together under that one name, and adding a field to the type adds it to every pump at once.
Why it matters: UDTs are what make a large project readable and what make reusable function blocks possible. They also cross networks as one block, which is cleaner and faster than a dozen loose tags.
Hook: Everything about one thing, in one tag.

How the word is built, where it came from, and what it sits beside in memory.

In a sentence

The PLC program uses a Structure for each conveyor motor, with fields for speed feedback, overload status, run command, and fault code.

How it is built

Where it came from

Origin: Middle French structure, from Latin structura, based on struere, meaning to build or arrange
Entered the language: 15th century
What changed: It moved from building and physical construction to organized arrangements, then became a computing term for data organized into fields.

How it is spelled

Pattern: The word keeps the Latin-derived struct- spelling.
Pattern: The final -ture follows a common noun ending seen in words such as fracture and architecture.

Spelled like

Broken into chunks

What it sits beside

Same subject

Same shape

IEC 61131-3 data types

motor data members

Phase 4: PLC Memory, Tags, and Instructions

The data a program moves and the instructions that move it, from a single true or false value up to a structured array.