Industrial Engineer · phase 2 of 16 · noun
Input Filter / Debounce
Time or digital filtering used to reject contact bounce and short signal disturbances.
The Explain card
- Plain English
- An input filter ignores changes that are shorter than a set time. It keeps a bouncing mechanical contact or a burst of electrical noise from looking like several real transitions.
- Example
- A pushbutton contact bounces for a few milliseconds every time it closes. With a 10 millisecond filter the PLC sees one press instead of five.
- Why it matters
- Too little filtering counts phantom parts and double triggers, and too much filtering misses a fast pulse from an encoder or a high speed sensor. The filter time is a setting on the card, and it is rarely looked at until something counts wrong.
- Hook
- The card waits a moment to see if you meant it.
Word knowledge
How the word is built, where it came from, and what it sits beside in memory.
In a sentence
During commissioning, set the PLC Input Filter to 10 ms before testing the conveyor's mechanical limit switch.
Why these words
- input English in plus put identifies the signal path on which the filter operates
- filter Medieval Latin filtrum, felt names the selective processing element
- debounce English de- plus bounce provides the alternative action-based name
Where it came from
- Origin
- English compound input filter, with filter from Medieval Latin filtrum; debounce is an English technical coinage from de- and bounce
- Entered the language
- 20th century
- What changed
- Filter moved from naming a porous material to naming selective electrical and digital processing; debounce specialized bounce for repeated switch transitions and added de- to mark their removal.
How it is spelled
- Pattern
- Input is a closed compound formed from in plus put.
- Pattern
- Filter keeps the common agent-noun ending -er.
- Pattern
- Debounce attaches the prefix de- directly to bounce.
Spelled like
- output
- throughput
- worker
- timer
- debug
- deactivate
Broken into chunks
-
input
- output
- throughput
-
filter
- filtered
- filtering
-
de-
- debug
- deactivate
-
bounce
- bounced
- bouncing
What it sits beside
Same subject
- digital input
- input module
- limit switch
- scan cycle
- signal conditioning
Same shape
- output filter
- input delay
- noise filter
PLC input settings
- input polarity
- input delay
- Input Filter
signal-conditioning terms
- low-pass filter
- hysteresis
- Debounce
Where it sits in the deck
Phase 2: PLC I/O and Field Signals
Where the controller meets the machine: discrete and analog signals, the wiring conventions behind them, and the field devices that send them.
