Industrial Engineer · phase 4 of 16 · noun

Mask

Bit pattern used to select which bits participate in a comparison, copy, or logical operation.

The Explain card

Plain English
A mask is a bit pattern that says which bits count. A one in the mask means look at this bit, a zero means ignore it, and the instruction applies that filter before it compares, copies or tests.
Example
A drive status word carries sixteen bits and you only care about three. A masked compare with those three bits set ignores the other thirteen, so the rung stays stable while unrelated bits flicker.
Why it matters
Masks are the clean way to pick fields out of packed network data. Written in hex they look like magic numbers, so name the mask tag for what it selects or nobody will ever touch it again.
Hook
Pay attention to these bits and none of the others.

Word knowledge

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

In a sentence

The PLC applies a mask to the drive status word before checking the run and fault flags.

How it is built
  • mask root a covering or screen
Where it came from
Origin
Middle French masque, from Italian maschera, with a deeper origin that is uncertain
Entered the language
1530s
What changed
It moved from a face covering to broader ideas of concealment, screening, and selective treatment in technical language.
How it is spelled
Pattern
A single syllable ends with the consonant cluster -sk.
Pattern
The final k is retained before suffixes, as in masked and masking.

Spelled like

  • task
  • desk
  • risk
Broken into chunks
  • mask
    • masked
    • masking
    • maskable
What it sits beside

Same subject

  • status word
  • bitwise AND
  • fault register
  • PLC
  • drive parameter

Same shape

  • ask
  • cask
  • flask

PLC logical instructions

  • AND
  • OR
  • XOR

Industrial control data words

Where it sits in the deck

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.

Neighbours in this phase