Glossary · Sensors and measurement
Rotary encoder
Also known as: Shaft encoder, Angle encoder
German: Drehgeber
In automation and motion control, a rotary encoder is a sensor that converts the angular position or movement of a shaft into electrical signals, either as pulses (incremental) or as a coded position value (absolute).
- Sensors
In one sentence
A rotary encoder converts the angle or rotation of a shaft into electrical signals, as incremental pulses or an absolute position value.
Example
A rotary encoder on the motor shaft of a servo axis provides position and speed feedback to the drive.
How it applies
- Engineering: Encoders are specified by principle (optical, magnetic, inductive), resolution, interface, shaft or hollow-shaft design and environmental rating. The interface must match the drive or counter input.
- Commissioning: Check counting direction, scaling and, for absolute encoders, the zero offset. Mechanical couplings must not introduce play.
- Safety: Encoders used for safe speed or position monitoring must be suitable for the safety function and its architecture, for example with diagnostics or redundant channels. An ordinary encoder does not qualify on its own.
- Documentation: Describe encoder type, mounting and the procedure after replacement in the maintenance manual.
Rotary encoder vs. resolver
In a narrow sense, a rotary encoder is a digital sensor with optical or magnetic scanning. A Resolver is an analog electromagnetic sensor. Both measure shaft angle, and the German Drehgeber often covers both.