FAQ - What Is the Difference Between Incremental and Absolute Rotary Encoders?

Q: What Is the Difference Between Incremental and Absolute Rotary Encoders?

A: 

The main difference lies in how each encoder type tracks and communicates position information.

Incremental Rotary Encoders

An incremental encoder generates a series of pulses as the shaft rotates. These pulses indicate relative position and must be counted from a known reference point to determine the actual position. Since the encoder only outputs changes in position, it requires a reset to the reference (or zero) position at startup. This type is ideal for applications where speed and direction are more critical than absolute positioning, and it's often more cost-effective.

Key features:

• Outputs pulses proportional to the rotational movement.

• It does not retain position data when powered off.

Absolute Rotary Encoders

An absolute encoder, on the other hand, provides a unique digital code (typically Gray code) for each shaft position. This code corresponds to an absolute position value, which means the encoder can report the exact angle of the shaft even after a power cycle, no homing or reference reset is required.

Key features:

• Outputs a distinct code for each position, representing the absolute angle.

• Retains position information even when power is lost.

• Ideal for systems that require high accuracy and reliability in position tracking.

Date/Revision History

First review 9/15/2025 V1.0

Author: 

Aimee Rivera, Technical Support Engineer

References

Technical Explanation for Rotary Encoders