Absolute Encoder vs Incremental Encoder

Position And Speed Monitoring  – Electric Motor Parts & Accessories Australia​

Absolute Encoder vs Incremental Encoder

What Is A Motor Encoder?

Controlling the machines in an electronics factory is made possible by the detection of linear and angular motion. These microcomputers often require information about the position, speed, and direction of rotation of an axle or shaft. This information must be converted into digital format. Optic encoders can be used to measure angular and linear positions. They are also known as shaft or rotary encoders. They are used in a variety of applications, including industrial and consumer equipment. Shaft encoders or rotary encoders can be either absolute or incremental.

An absolute encoder gives position information only when power is lost. An incremental encoder can be used to provide velocity and direction information. Both can be used with linear and angular displacements. However, they work differently. Let’s examine how they differ.

What is an Absolute Encoder and how do you use it?

Absolute encoders have a unique code that represents each shaft position. It provides the digital output that represents the absolute displacement. When the system is turned on, the actual position value is immediately measured. 

An absolute encoder does not require a counter, as the measured value can be derived directly from the graduation patterns. It gives the digital output that corresponds to the position. 

Each bit position can be encoded separately using a separate LED pair. Each code is an absolute angular position for the shaft during its rotation. An absolute encoder uses a  Gray encoder, where one bit can change at a given time. This reduces errors in encoder communication. They can be broken down into single-turn or multi-turn encoders.

What is an Incremental Encoder Used For?

In an electro-mechanical device, an incremental encoder transforms the angular position on the shaft into digital signals or pulse signals. It produces a set number of pulses per revolution and provides a pulse for every increment that corresponds to the revolution. 

It can only measure the change in position and not the absolute position. It cannot, therefore, specify the relative position to any reference. The angular position and number of pulses generated are proportional. Incremental encoders can be used when velocity, velocity and direction information are required. Each time the device turns on or is reset, it counts from zero and generates an outgoing signal for each shaft movement. You can further subdivide the types of incremental encoders into quadrature encoders or tachometers.

Basics of Absolute Encoders vs. Incremental Encoders

These are both electro-mechanical devices that measure the angular and linear positions of the shaft, and then convert them into digital signals or pulse signals. An absolute encoder uses a unique code to identify each shaft position. An incremental encoder generates an outgoing signal every time the shaft turns at a specific angle. The number of pulses generated is proportional to the shaft’s angular position. An incremental encoder measures the change in position and not the absolute position.

Operating Mechanics of Absolute Encoders vs. Incremental Encoders

Absolute encoders consist of a binary-coded disk that is mounted on the shaft so it rotates with it. Every shaft’s angular position can be described using a variety of output channels. As the required resolution increases, so does the number of channels. It is not an incremental encoder that does not lose position information if the power goes out. An incremental encoder on the other hand provides an output signal for a specific increment of the angular location of the shaft. This is determined by counting the output pulses relative to a reference point.

Cost Efficiency & Comparison

Because the code matrix on the encoder disk has more complexity and requires more light sensors, an absolute encoder usually costs twice as much as the incremental encoders. Because the encoder disk has a limited number of tracks, the resolution can be reduced. It is, therefore, more costly to achieve finer resolutions without adding additional tracks. Incremental encoders are, however, simpler than absolute encoders and therefore more expensive.

Stability & Steadiness

Absolute encoders offer greater performance, more accurate results and lower overall costs. Absolute angle readings can be provided, so even if a reading is not taken, it will not affect the next one. The accuracy of any reading does not affect the particular reading. A device with an incremental encoder must be powered on during operation. The system will display an error if the power goes out. This can slow down the system’s performance. Absolute encoders will not lose their position information in the event of a power outage.


The incremental encoder must be powered during operation. If the power goes out, the reading needs to be re-initialized. Absolute encoders require power only to take a reading. Because it can provide absolute angle readings, the accuracy of a particular reading does not depend on its previous reading, however. An absolute encoder’s code matrix is typically more complicated than an incremental encoder. Because it is simpler, an absolute encoder will usually cost twice as much.

What Is A Motor Encoder?

What Is A Motor Encoder?

What Is A Motor Encoder?

What Is A Motor Encoder?

What is a motor encoder?

Overview of a Motor Encoder

An encoder is an electromechanical device that provides an electrical signal for speed and/or places control. An encoder converts mechanical motion into an electric signal, which is used by the control systems to monitor parameters and adjust if necessary. The type of application determines the parameters to be monitored. They can include speed, distance and RPM. Closed-loop feedback and closed-loop control systems are terms that refer to applications that use encoders or any other sensors to control certain parameters. This article (click to jump section):
  • What is a motor encoder?
  • How do I specify a motor encoder?
  • Motor encoder mounting options
  • Types of motor encoder technology

What is a Motor Encoder?

Motor encoders are rotary encoders that are attached to electric motors. They provide closed-loop feedback signals and track the speed and/or location of the motor shaft. There are many options for motor encoder configurations, including incremental, absolute, optical, magnetic, shafted, hub/hollow shaft and others. The type of motor encoder chosen depends on a variety of factors, including the type of motor, the application, and the mounting configuration.

Most Popular Types of Motor Encoders

The type of motor used in the application determines the first motor encoder selection. These are the most popular motor types:

AC Motors Encoders

Because they are both economical and durable, AC induction motors are a popular choice for general automation machine controller systems. Motor encoders can be used to control AC motors’ speed more precisely and require more robust IP, shock, and vibration parameters.

Servo Motor Encoders

Permanent magnet motor encoders, also known as servo motors encoders, provide closed-loop feedback control systems for applications that require greater precision and accuracy. However, they are less robust than AC induction motors. Modular, incremental, or absolute motor encoders are available for servo motors. This depends on the level and accuracy of the required resolution.

Stepper Motor Encoders

Stepper motors can be cost-effective and precise. They are often used in open-loop systems. An incremental motor encoder can be mounted to stepper motors to provide speed control. This will enable the stepper motor system to achieve closed-loop feedback. In some cases, stepper motor encoders are also available to improve the control of stepper motors. They provide precise feedback about the position of the motor shaft relative to the step angle.

DC Motor Encoders

DC motor encoders can be used to provide speed control feedback for DC motors. An armature or rotational rotor is made up of wound wires and rotates within a magnetic field created from a stator. The DC motor encoder is a device that measures the speed of the rotor and provides closed-loop feedback to drive for precise speed control.

Mounting options for motor encoders

Mounting options play a major role in motor encoder selection. The most popular options are:
  • Motor encoders with shafts: A coupling method is used to connect the motor shaft and motor encoder shaft. Although the coupling provides mechanical isolation and electrical isolation from the motor shaft, it can increase cost due to the longer shaft required to mount the encoder.
  • Hub/Hollow shaft Motor encoders: The hollow shaft encoders attach directly to the motor shaft using a spring-loaded tether. This is a simple method that requires no shaft alignment and can be installed quickly. However, it must be done with care to ensure electrical isolation.
  • Bearingless Motor Encoders – Also called ring mount, this mounting option consists of a sensor assembly that is composed of a ring mounted on the motor face and a magnet wheel mounted on its shaft. This mounting option for motor encoders is most commonly used in heavy-duty applications such as paper, steel, and cranes.

Different types of encoder technology

The motor encoder technology required will depend on the application. There are two main types of motor encoder technology:
  • Incremental encoders: An incremental motor encoder’s output is used to control the speed of a motor shaft. Learn more about incremental encoder technology.
  • Absolute Encoders (Absolute Encoders): An absolute motor encoder’s output indicates the motion and position of the motor shaft. Absolute motor encoders can be found on Servo Motors, where precise positioning is needed. Learn more about absolute encoder technology