Guide · Encoders
Absolute vs incremental encoder: what is the difference?
An incremental encoder counts movement from a start point and needs a reference run after power-up. An absolute encoder reports its actual position as soon as it powers up. Star Automations is an independent multi-brand repair company and is not an OEM service centre.
Short answer
An incremental encoder sends pulses as the shaft turns, and the controller counts them. It does not know where it is until it finds a reference (home) position. An absolute encoder outputs a unique position value for every shaft angle, so it knows its position immediately after power-up.
Side by side
| Incremental | Absolute | |
|---|---|---|
| Output | Pulses (A, B, Z channels) | Position code (SSI, BiSS, EnDat, fieldbus) |
| After power-off | Position lost; needs homing | Position kept |
| Multi-turn | Counted by the controller | Single-turn or multi-turn types |
| Wiring | Simple | More signals or a data interface |
| Typical use | Conveyors, spindles, speed feedback | Servo axes, robots, lifts, positioning |
What fails in each
- Incremental: lost channels, noisy counts, damaged cable, worn bearing.
- Absolute: communication errors, lost multi-turn position, battery-backed memory faults, damaged cable.
- Both: contamination of the sensing element and shaft or bearing damage.
See the incremental and absolute encoder repair pages, and the guide on checking servo encoder alignment.
Questions
Can I replace an incremental encoder with an absolute one?
Only if the controller or drive supports the absolute interface. Check the interface and resolution first.
Do absolute encoders need a battery?
Some multi-turn types keep their count with a battery, others use mechanical or energy-harvesting multi-turn. Check the model.
Is Star Automations an OEM service centre?
Star Automations is an independent multi-brand repair company and is not an OEM service centre.
How fast can a repair be done?
Emergency same-day, urgent 3 working days and standard 7 working days are available where the fault and parts allow. The timeline is stated on the quote.
Send the model and the fault.
WhatsApp or call +91 97866 22233, or email info@starautomations.com.