Essentially an electro-mechanical device, an encoder is able to provide motion control system users with information concerning position, velocity and direction.
There are two types of encoders; the selection is normally determined by whether there is a need to retain position in the event of a power failure.
Incremental and Absolute encoders are the most common in the growing range of encoder products, and while they both perform similar roles, at the same time, they also have varying features and benefits. Incremental lose their position when the power is removed but absolute always transmit their current position when power is restored.
In the past the resolution of the encoders was determined by the graduations on an optical disk, and in the case of multi turn, the position of small internal gears, today there is a new breed of encoders which uses advanced magnetic technology which allows the user to alter the resolution on site to suit their specific requirements.
Absolute (programmable shaft) encoders work by determining the angular position using magnetic sensor technology. A permanent magnet is fixed to the end of the encoder’s shaft creating a varying magnetic field as it rotates, this information is sampled by a sensor that in turn generates a unique absolute position reading.
The advantages of absolute encoders include:
- Maintain Position Information When Power is Lost
- Compact Size – Down to 36 mm in diameter
- Standard 36 and 58mm housings
- Robust and durable
- Mechanically simple and economical − no battery, no gears
- Compact design for installation in small space
- Stainless Steel, ATEX and SIL Encoders housings
- High Shock and Vibration Resistance
- Simple programming
- Can be used in dangerous and/ hazardous environments
- Available to integrate with most industrial serial protocols
Absolute encoders ensure reliable positioning and never require calibration which increases the safety and efficiency of construction machines, wind turbines or solar plants. Their compact size also makes them ideal for applications ranging from healthcare equipment to factory automation.
Incremental (programmable shaft) encoders are designed to provide high resolution measurements using an incremental interface and are available with common configurations such as A, B, Z, and inverted signals available as HTL (Push-Pull) or TTL (RS422).
Incremental encoders have a number of features and benefits including:
- Flexible Scaling Functionality
- Standard 36 and 58mm housing
- Compact Size Down to 36 mm in diameter
- Optional Stainless Steel and Heavy Duty Housings Available
- High Shock and Vibration Resistance
- Simple programming with a mobile phone
- Pulse count up to 16,384
Incremental encoders are ideal for various industries due to their small size, economical design and easy programming, making them suitable for motor speed feedback, material handling applications and also for OEMs.
Thanks to their easy programming, both Incremental and Absolute programmable shaft encoders are designed to decrease machinery downtime and, now with the development of dual encoders, can provide an even greater simplification of inventory for users.
The new generation range of Incremental and Absolute programmable encoders are available from Plant and Control Automation (PCA) which stocks a wide range of these German-made Fraba/Posital encoder products..
PCA offers Absolute and Incremental encoders with solid or blind hollow shafts.
To find out more about the PCA range of encoders, click here