What is the encoder used for? What type of device is an encoder? What is encoder output?

The encoder is a sensing device that gives feedback. An encoder can transform motion into electrical signals that control devices of motion control systems can read. The encoder sends feedback signals to determine parameters like position, count, speed, and direction. A control device may use this information to send commands for any specific function.

In cut-to-length applications, encoders have a measuring wheel to tell the control device about the amount of material that needs to be fed, so the control device understands when to cut.

In an observatory, an encoder tells an actuator the position of a moveable mirror for giving positioning feedback.

Encoders are sensing devices that give feedback regarding the motion of objects for controlling systems. It allows the system to understand the correct movement of objects and adjustments required depending on the action and position.

Several ways are there by which encoders can be characterized. Commonly used encoders include linear encoders, angle encoders, and rotary encoders.

Linear encoders

They deal with the motion of objects along a  straight line as in cut-to-length applications. Linear encoders use transducers for the measurement of the distance between two points.

 Between the encoder transducer and the object in motion runs a cable. During the object’s movement, the transducer collects data from the cable. It generates a digital or analog output signal to establish the object’s position or direction.

Rotary Encoder

Rotary encoders give feedback about a rotating body’s movement, like a motor’s shaft. This encoder is used to convert the angular position of a moving shaft into digital or analog output signals for enabling a control system about the shaft’s speed and position.

Rotary encoders may have shafts or can have a design called thru-bore encoders. They are available in different sizes and come with a set screw or clamp mounting options, making them appropriate for machine design applications. Flanges prevent the encoder from rotating along with the moving shaft.

Angle encoders

They work in a similar way to which rotary encoders work. However, they offer more accuracy than angle encoders.

Absolute encoders give a unique output digitally coded, or an address, for every unique encoder position.

On the other hand, an incremental encoder will give a pulse or count as output within regular predetermined intervals.


Encoders can detect linear displacement or rotation angles. Devices that operate at high speed and require high levels of accuracy use encoders. Encoders find their use in industrial robots that factories use. They include welding and assembly robots, machining centers and automatic guided machines.

The way the motor rotation is controlled by detecting its rotation speed and angle using an encoder is known as feedback control. It is a closed-loop method.

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