Industrial Engineer · phase 4 of 16 · noun

Tag / Address

Symbolic name or numeric location used to reference I/O, memory, or structured data.

The Explain card

Plain English: A tag is the name you give a piece of data, and an address is the physical or numbered place it lives. Newer controllers let you work in names, and older ones make you work in addresses.
Example: Conveyor1_Run is a tag. The same bit also has an address that says input card, slot one, point three, and on a tag based controller that address hides behind the name you chose.
Why it matters: Tag names are the documentation nobody has to write, so a naming convention decided on day one pays for itself for the life of the machine. An address tells you where, a good tag tells you what.
Hook: The address is the street, the tag is the sign on the door.

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

In a sentence

During commissioning, the technician monitors the Tag Motor_1_Run_FB while checking the motor starter's auxiliary contact.

How it is built

Where it came from

Origin: Middle English tagge, possibly from a Scandinavian word related to Swedish tagg, meaning point or prickle
Entered the language: 14th century
What changed: It moved from a metal tip or hanging piece to an attached label, then to a symbolic identifier in computing and controls.

How it is spelled

Pattern: The short vowel is closed by a final consonant, and the final g doubles before vowel-led suffixes: tagged and tagging.

Spelled like

Broken into chunks

What it sits beside

Same subject

Same shape

PLC reference styles

tag name elements

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.