Industrial Engineer · phase 4 of 16 · noun
Bit / BOOL
Single Boolean value that is either false or true.
The Explain card
- Plain English
- A BOOL is a single bit that is either true or false, on or off, one or zero. It is the smallest thing a controller stores and the thing most of its decisions are made from.
- Example
- Motor_Running is a BOOL. So is every contact and coil in a ladder program, and every discrete input and output on a card.
- Why it matters
- Bits pack together into bytes and words in memory, which is why a badly aimed word move can wipe thirty two of them at once. Keep bits in named tags rather than in slices of an integer unless you enjoy that kind of surprise.
- Hook
- The atom of control.
Word knowledge
How the word is built, where it came from, and what it sits beside in memory.
In a sentence
The PLC stores the motor overload contact as a Bit and tests it before energizing the starter output.
How it is built
- b- clipped element from binary
- -it clipped element from digit
Where it came from
- Origin
- English computing coinage from binary digit, attributed to John Tukey
- Entered the language
- 1940s
- What changed
- The coinage joined clipped parts of binary and digit; PLC usage later placed it beside the IEC type name BOOL.
How it is spelled
- Pattern
- A single consonant closes the short-i syllable.
- Pattern
- The plural is formed regularly as bits.
Spelled like
- fit
- hit
- sit
Broken into chunks
-
bit
- bitmap
- bitwise
- bitfield
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.
