Industrial Engineer · phase 3 of 16 · noun
Function Block
Reusable program unit with defined inputs, outputs, and retained internal state when instantiated.
The Explain card
- Plain English
- A function block is a reusable piece of logic that keeps its own memory. You make an instance of it, give it inputs, and it remembers its state from one scan to the next.
- Example
- A timer is a function block. Every TON instance keeps its own accumulated time, so twenty conveyors can share one timer design and twenty separate counts.
- Why it matters
- A block written once for one motor, tested and locked, runs identically on every motor in the plant. Fix a bug in the block and every instance gets the fix, which is how large projects stay maintainable.
- Hook
- A function with a memory of its own.
Word knowledge
How the word is built, where it came from, and what it sits beside in memory.
In a sentence
The PLC executes the MotorStarter Function Block after reading the start pushbutton and overload contact, then sends its run command to the output module.
Why these words
- function Latin functio, performance or execution identifies the purposeful operation represented
- block Middle French bloc, a solid piece frames the operation as a bounded programming element
Where it came from
- Origin
- English compound formed from function and block
- Entered the language
- 20th century
- What changed
- Function moved from performance or duty to a technical operation, while block developed the sense of a distinct unit in diagrams and computing.
How it is spelled
- Pattern
- Function ends in -tion, commonly pronounced as shun.
- Pattern
- Block uses final -ck after a short vowel sound.
Spelled like
- operation
- section
- clock
- stock
Broken into chunks
-
funct
- functional
- functionary
-
tion
- action
- operation
-
block
- blockage
- blocker
What it sits beside
Same subject
- Function Block Diagram
- input parameter
- output parameter
- instance data
- ladder diagram
Same shape
- terminal block
- data block
- organization block
IEC 61131-3 program organization units
- program
- function
- function block
PLC programming languages
Where it sits in the deck
Phase 3: PLC Program Organization and Execution
How the logic is arranged and how the scan actually runs it, which is the difference between code that works and code that works every time.
