Rotary encoders convert rotational motion into digital signals

Encoders for every application

Rotary encoders are widely used in manufacturing and production processes to indicate precise positioning of linear distance, speed, angular displacement and direction of rotation.

Traditional optical encoders are susceptible to damage from impact.

ifm encoders use magnetic technology and are more robust, not easily damaged by impact or vibration. Embedded IO-Link technology provides process transparency.

Magnetic encoders

Magnet rotates over chip, pulses generated by changes in the magnetic field

Optical encoders

Pulses generated when light from through-beam optical sensors passes through gaps in a glass disk

ifm's Magnetic encoders vs. Optical encoders
Magnetic technology	Optical technology
High resolution and accuracy comparable to optical encoders in a smaller package with a lower price point	High resolution and accuracy but difficult and expensive to manufacture
Fewer components for more robust solution	Multiple parts, including glass disc, are prone to breaking in high shock and vibration applications
Programmable resolution and output	Fixed resolution and output
Models available with IO-Link for process transparency

Encoder types

ifm offers both incremental and absolute encoders, in solid and hollow shaft configurations, with and without display, and with and without IO-Link.

Incremental encoders

Incremental encoders generate a specific number of pulses as the shaft makes a complete revolution. The more pulses per revolution, the fine the resolution of the encoder. Incremental encoders simply provide a series of digital signals corresponding to speed, direction or distance traveled.

Absolute encoders

Absolute encoders provide a unique numerical value for each angular position of the shaft. They are used in applications requiring highly accurate information on distance, speed, direction and absolute position.

Absolute encoders are further divided into single-turn and multi-turn.

Incremental encoders	Speed and angle detection during one revolution Pulse signal Evaluation unit is required No position traceability in case of power failure
Absolute single-turn encoders	Absolute position traceability for a single revolution even when unpowered
Absolute multi-turn encoders	Absolute position detection over several revolutions even when unpowered

Comparison of encoders
	Incremental	Incremental via IO-Link	Absolute single-turn	Absolute multi-turn	Absolute multi-turn via IO-Link
Speed
Resolution
Revolutions	1	1	1	1 / ∞	1 / ∞
Position values	Relative	Absolute	Absolute	Absolute	Absolute
IO-Link infrastructure required
Position memory after power break
Fieldbus compatibility
Noise immunity
Settings required