Industrial Engineer · phase 4 of 16 · noun
Retentive Timer
Timer that preserves accumulated time until a reset instruction clears it.
The Explain card
- Plain English
- A retentive timer keeps its accumulated time when its input goes false. It picks up where it left off when the input returns, and only a reset instruction clears it.
- Example
- A filter needs changing after 100 hours of running. A retentive timer counts only while the pump runs, across dozens of starts and stops, and flags maintenance when it reaches the preset.
- Why it matters
- A plain timer starts over every time the input drops, so it can never total intermittent time. The retentive one needs an explicit reset, and forgetting that reset means it trips once and never again.
- Hook
- A stopwatch that pauses instead of resetting.
Word knowledge
How the word is built, where it came from, and what it sits beside in memory.
In a sentence
In the conveyor PLC, a Retentive Timer tracks cumulative motor run time across brief stops and triggers lubrication after eight operating hours.
Why these words
- retentive Medieval Latin retentivus, capable of retaining adjective specifying the timer's memory behavior
- timer English time plus the agent suffix -er head noun naming the timing instruction
Where it came from
- Origin
- English technical phrase combining retentive, from Medieval Latin retentivus, with timer, formed from time plus -er
- Entered the language
- 20th century
- What changed
- Retentive narrowed from a general adjective for holding something to a controls modifier describing stored instruction state, while timer became a name for an automated timing device or instruction.
How it is spelled
- Pattern
- retentive ends with the adjective suffix -ive
- Pattern
- timer drops the silent e of time before -er
- Pattern
- the phrase follows an adjective-plus-noun pattern
- Breaks the pattern
- retentive uses the Latin stem retent- rather than the modern English spelling retain-
Spelled like
- preventive
- selective
- writer
- driver
Broken into chunks
-
re
- return
- restore
-
tent
- retention
- detention
-
ive
- active
- protective
-
time
- timed
- timing
-
er
- counter
- controller
What it sits beside
Same subject
- non-retentive timer
- on-delay timer
- off-delay timer
- reset instruction
- accumulator
Same shape
- retentive counter
- programmable controller
- protective relay
PLC timer instructions
- retentive timer
- on-delay timer
- off-delay timer
retentive PLC elements
- retentive timer
- retentive counter
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.
