Industrial Engineer · phase 1 of 16 · noun

Rack / Chassis

Mechanical assembly that holds controller modules and connects them through a backplane.

The Explain card

Plain English
The rack is the metal frame the modules plug into. It holds them in a row, fixes their slot numbers and joins them to a shared bus.
Example
A seven slot chassis might carry a power supply on the end, a CPU in slot 0, an Ethernet card in slot 1 and I/O cards in the rest.
Why it matters
Slot position becomes part of an address, so moving a card moves every tag that points to it. Size the rack for the modules you will add next year, because a full rack means a second one and a new address space.
Hook
The rack is the street and the slots are the house numbers.

Word knowledge

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

In a sentence

In the hardware configuration, assign the analog input module to slot 4 of rack 0 so the infeed load-cell tags keep that slot number after the download.

How it is built
  • rack root frame; something stretched or set in a row
Where it came from
Origin
Middle English rakke, probably from Middle Dutch rec, a framework, from a Germanic root meaning to stretch, kin to German recken
Entered the language
c. 1300
What changed
First a stretching frame for hanging things, then the torture device that stretched a body the same way. The frame sense stayed in furniture and shops, moved into telephone equipment bays cut to a 19-inch standard, and plant catalogs kept that bay sense beside the French loan chassis.
How it is spelled
Pattern
After a short vowel, English writes /k/ as ck, never kk
Pattern
ck already counts as the doubled consonant, so racking and racked keep a single ck
Breaks the pattern
the wreckage word wrack looks like a variant but keeps a silent w; rack and ruin is historically that word

Spelled like

  • pack
  • stack
  • track
  • back
Broken into chunks
  • ack
    • back
    • pack
    • stack
    • track
  • ck
    • lock
    • dock
    • clock
What it sits beside

Same subject

Same shape

  • pack
  • stack
  • track
  • wrack

PLC hardware

Plant-floor frames

  • Chassis
  • Enclosure
  • Cabinet

Where it sits in the deck

Phase 1: PLC Controller Hardware

The box itself, from processor and rack to the modules that plug into it, because nothing else in the deck lands until you know what a PLC physically is.

Neighbours in this phase