Industrial Engineer · phase 3 of 16 · noun

Event Task

Task triggered by a configured hardware, motion, network, or program event.

The Explain card

Plain English
An event task runs once when something specific happens. The trigger can be an input module reporting a change, a motion axis reaching a position, a consumed tag arriving, or a program instruction.
Example
A registration mark on a web triggers an input change event. The task captures the encoder position within microseconds instead of waiting for the next scan.
Why it matters
When a scan of ten milliseconds is too slow, the event task is how you respond in the moment the thing happens. It also runs only as often as the event does, so it spends no CPU time waiting.
Hook
Do this now, then go back to sleep.

Word knowledge

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

In a sentence

In Studio 5000, the engineer assigns an Event Task to process module input data when a new sample arrives.

Why these words
  • event Latin eventus, outcome or occurrence identifies the occurrence around which the phrase is organized
  • task Old North French tasque, duty or imposed work names the schedulable unit of controller work
Where it came from
Origin
English technical compound formed from event and task in real-time and event-driven computing
Entered the language
20th century
What changed
Event narrowed from a general outcome to a detectable occurrence, while task shifted from assigned work to a schedulable program unit.
How it is spelled
Pattern
It is an open compound written as two separate words.
Pattern
Both words retain their ordinary spellings when combined.

Spelled like

  • event handler
  • event queue
  • Periodic Task
  • Continuous Task
Broken into chunks
  • event
    • eventual
    • eventuality
  • task
    • multitask
    • tasking
What it sits beside

Same subject

Same shape

Logix task types

event-related programming terms

  • event handler
  • event queue
  • event source

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.

Neighbours in this phase