Glossary · Sensors and measurement
Incremental encoder
Also known as: Incremental rotary encoder, Quadrature encoder
German: Inkrementalgeber
In industrial automation, an incremental encoder is a position encoder that outputs a number of pulses per movement, usually as two phase-shifted signals A and B plus a reference pulse. The controller counts the pulses to determine position and direction.
- Sensors
In one sentence
An incremental encoder outputs pulses per movement; the controller counts them for position and speed and needs a reference run after power-up.
Example
An incremental encoder with 2,048 pulses per revolution on a conveyor motor lets the controller track product positions between sensor stations.
How it applies
- Engineering: Resolution is given in pulses per revolution; quadrature evaluation of A and B can increase it fourfold and gives the direction. Output types include TTL/RS-422 and HTL; they must match the counter input.
- Commissioning: After power-up, the position is unknown. A reference run to a reference switch or the zero pulse establishes it. Check counting direction and scaling.
- Maintenance: Lost pulses from interference or cable damage cause position errors that accumulate. Shielding and correct grounding matter.
- Documentation: Describe the referencing procedure and when it must be repeated, for example after power loss or encoder replacement.
Incremental encoder vs. absolute encoder
An incremental encoder measures change and needs a reference. An Absolute encoder outputs the absolute position directly. Incremental encoders are simpler and common for speed feedback.