What are the differences between absolute and incremental rotary encoders? Which one do I use when? These questions come up all the time. Our customers want to know.
Rotary encoders in general connect to a shaft and output pulses as the shaft rotates. You can determine the speed of an object based on how many pulses there are per revolution. The number of pulses that make up one full turn of the shaft determines the resolution. Incremental encoders have a resolution of up to 50,000 pulses per revolution (ppr) while absolute encoders have a resolution of up to 16 bits or 65,536 ppr.
The following video lets you see an incremental rotary encoder in action. It shows how bottling is done in the packaging industry.
Incremental Rotary Encoder Advantages
- Good for simple pulse counting or frequency monitoring applications
- Good for speed, direction, and position monitoring
- More cost effective than an absolute encoder
- Less complex than an absolute encoder
Absolute encoders go a step further by letting you determine the exact position of a machine, and storing that information.
Absolute Rotary Encoder Advantages
- Remembers an object’s position after a power outage
- Continuous position monitoring
- Speed, scaling, preset, fieldbus functions
What can you do with rotary encoders? Which industries are they used in?
Both kinds of rotary encoders, absolute and incremental, are used by the same industries, including:
- Print & Paper Industry
- Material Handling
- Machine & Plant Engineering
- Doors, Gates, & Elevators
- Packaging Industry
- Food & Beverage
- Mobile Equipment
- Renewable Energy
- Oil & Gas
So which type of encoder should you choose? It all boils down to customer preference and application requirements. For a customer who wants to use a certain type of protocol, such as PROFINET, Ethernet, or J1939, or who wants to keep track of the exact numerical value at which the encoder stopped during a power outage, the right choice would be an absolute encoder. For a customer who is conscious of keeping costs to a minimum and who is okay with using a homing sequence to find and set the starting point of an encoder to zero after a power outage, the right choice would be an incremental encoder.
In the end, the best choice is the one that works for you.