Industrial Engineer · phase 2 of 16
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.
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.
