Absolute vs. Incremental Rotary Encoders: Choosing the Best Option for Your System
A well-liked and tested method for determining a rotating shaft’s position, speed, or direction of motion is a rotary encoder. Although there are many varieties, the absolute encoder and the incremental encoder are the two primary types.
Absolute encoders
The number of distinct data words over a single rotation is represented by the bits that make up the encoder’s resolution. Absolute encoders come in two varieties: single-turn and multi-turn. Single-turn encoders provide position data for a single 360° revolution, which is repeated for each shaft revolution. The multi-turn type’s turns counter allows the encoder to output both the number of revolutions and the shaft position.
Incremental encoder
The number of pulses per revolution (PPR), which is equal to the number of high pulses from either of the square-wave outputs, is the unit of measurement for the resolution of an incremental encoder, one of the types of rotary encoders. For an incremental encoder to deliver useful positional information, it needs to be referenced to a known fixed point. The index pulse of the encoder is this “home” place. The relative incremental change in rotation from the index pulse is then tracked to determine the shaft’s absolute position.
Absolute vs. Incremental encoder
Absolute encoders have the unusual ability to start up as soon as a system is powered on. By providing the shaft’s position in a 360-degree rotation and, in the case of multi-turn encoders, the number of rotations the shaft has completed, absolute encoders can give an operator precise location information in addition to speed and direction. In order to generate the same information that absolute encoders can supply instantaneously, systems that employ incremental encoders for location determination usually require additional software and programming.
This is only one example of how incremental encoders could end up costing more than their absolute counterparts over time. Incremental encoders are usually favored by a significant margin because of the upfront expense. Simply said, absolute encoders have more parts to guarantee higher resolution, which raises the initial outlay of funds.
Absolute rotary encoders are capable of far more than incremental encoders. However, they are more expensive initially, and because of their mechanical intricacy, they need more upkeep and care. Examine the needs of your system and the circumstances in which it will function before deciding on a solution. Incremental encoders might be the ideal choice for your work, and their more straightforward mechanical design offers a useful level of dependability and assurance.
