Difference Between an Absolute and Incremental Encoder

Both incremental and absolute encoders are used to measure angular position in a broad range of industries and applications including machine tools, automation, packaging, printing and label/marking equipment.

They can also be referred to as rotary encoders or shaft encoders with the absolute/incremental referring to the working principle of the encoder, these two principles operate differently. 

What is the difference between an absolute and an incremental encoder?

Absolute Encoders 

Both absolute and incremental encoders measure angle position based on the position of the shaft. Within an absolute encoder, this position is retained regardless of whether the encoder is powered or not, even if a movement is made without power to the encoder and power is reapplied, the encoder knows its true new position. 

These can either be single turn or multi-turn, whereby the requirement is to know not only the position over one turn of the shaft but how many turns have been made in total. Multi-turn encoders are suited to applications where complex or lengthy positioning measurements are involved. Single-turn encoders are more suited to short travel applications where position measurement is required within a single turn of the encoder. 

Our absolute encoders have the following advantages;

• Non-volatility memory (true position is not lost if power is lost)
• Continuous reading of position is not required
• No battery backup or gear function due to the patented ‘Endra’ technology from our supply partner Wachendorff.
• No traditional optical disk, thus reducing the component costs associated with this, again due to the patented ‘Endra’ technology from Wachendoff.
• High resolution with up to 16-bit single and 44-bit multi-turn.

Incremental Encoders 

An Incremental encoder is electro-mechanical, it works by transforming the angular position of the shaft into digital or pulse signals using an optical disk. A certain number of pulses are generated per revolution and each pulse is an increment corresponding to the defined resolution. An incremental encoder can measure the change in position but not the absolute position. 

Every time an incremental encoder is switched on the pulse is counted from zero, this means that the position is not stored and a ‘reset or reference’ position must be obtained before the encoder begins counting again. This is the main difference between an absolute and an incremental encoder. 

Advantages of Incremental Encoders

• Typically lower cost than absolute encoders
• Less complex than absolute encoders
• High noise immunity 

Uses for Absolute and Incremental Encoders 

Because they take similar measurements, both absolute and incremental encoders can be used for the same applications - contact us if you have an application and would like advice on which type of encoder to use. 

Application examples are;

• Cut to length applications 
• Jacks for railroad cars
• Bottle rotation for label application
• Printing applications 
• Elevator position applications 
• Automated assembly lines 
• Packaging machines 

Encoders are used throughout many industries and are well suited to a whole host of applications in industries such as;

• Robotics
• Motorsport
• Heavy-duty applications 
• Automation 
• Factory applications 
• Industrial applications 
• Machine building
• Food industry
• Drink technology
• Quality control
• Cranes and construction 

Absolute and Incremental Encoders from Variohm 

We can offer a range of absolute and incremental encoders from our supplier Wachendorff. Take a look at the different types we have on our website;

• Absolute rotary shaft and hollow shaft encoders
• Incremental rotary shaft and hollow shaft encoders 

Wachendorff encoders are;

• Rugged and industrial to suit any application
• Standard range and custom versions 
• Offer express production to cut down lead times
• Complete systems offered 
• Offered with an unrivalled 5-year manufacture warranty

For more information on encoders or any of the products in our portfolio please contact us.