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How Rotary Encoder Works

What is Rotary Encoder?

A rotary encoder also called a shaft encoder is a position sensor that is used to detect the angular position and speed of electrical signals. They process the signals based on the rotational movements i.e clockwise or anti-clockwise movements.

Angular position: As the shaft rotates around the center axis, an angular position exists for each location along the path of travel.

Absolute Rotary Encoders-Rotary Encoders Online, absolute linear encoder, high precision encoder
               Rotary Encoder


Classification of Rotary Encoder

There are many types of rotary encoders that can be classified based on output signal or sensing technology.


The most common type:

Absolute: In this current position will be known as soon as the power is applied.

Incremental: This encoder immediately reports change in the position without reporting track of the absolute position.

How Rotary Encoder Works?

The inside of encoder consists of a evenly spaced disk. And a series of electrically charged pads are placed around the outer portion of disc. On top of these pads there are 3 contact pins – A, B  and C as given below:

                    Diagram to understand how rotary encoder works


Pin A and B are set of fixed position contacts called as the clock and data line which are 90 degrees out of phase.

When the disk starts rotating, pin A (clock) and pin B (data lines) make contact with pin C (the electrically charged pad). This further creates square wave output signals as shown in the above figure.

These output waves can also be used to find the angular position by counting the number of pulses of the signal.

The positioning of pin A and pin B is in such a way that it makes the shaft turn clockwise or anti-clockwise and based on the direction of the shaft the travel direction is determined.

Check out the diagram for a simplified explanation of the working and classification of the rotary encoder:


Operating Principle of Rotary Encoder


Sr Indus provides 2 types of rotary encoder:

1. Hengstler Incremental Rotary Encoder:

Incremental Rotary Encoder- Rotary Encoder working | SRIE

We provide Hengstler incremental rotary encoder for robust heavy-duty products. This encoder interrupts a beam of light from a light-emitting diode which determines the number of lines in resolution. The information is then available as a signal at the encoder output. The incremental rotary encoder can provide 10,000 pulses per revolution.

For more information and technical specification of various types of incremental rotary encoder check out this page.


2. Hengstler Absolute Rotary Encoder:

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The Hengstler absolute rotary encoder are innovative engineering and easy to operate. This sophisticated piece of engineering is in a position to provide accurate data for motor feedback and automation. They come equipped up with the BiSS sensor interface which makes them ideal for all equipment in the coming future.

For more information and technical specification of various types of absolute rotary encoder check out this page.


Sr Indus Electro System is Hengstler distributor as well as supplier in India. Contact us now to find out the best price on the Hengstler products.

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