Incremental Encoder Signal Type
An incremental encoder is a device that outputs pulse signals to reflect rotational increments. Each time the encoder’s shaft rotates, it generates a series of evenly spaced pulses. By counting these pulses, the control system can calculate the displacement, speed, and direction of rotation. Incremental encoders typically output square wave or sine wave signals, making them ideal for speed and position control applications.
Working Principle of Incremental Encoders:
Pulse Signal: A pulse is generated every time the shaft rotates a fixed angle.
Direction Signal: The system determines the direction of rotation by analyzing the phase difference between signals A and B.
Reference Signal: Some incremental encoders also output a Z signal that marks a specific position, like the home position.
Incremental encoders only provide relative position data and do not offer absolute position feedback. Therefore, if the system experiences a power outage or restart, position data will be lost, and the encoder needs to be reset. This type of encoder is suitable for applications where absolute position tracking is not necessary, such as motor control and speed/direction monitoring in automation systems.
Absolute Encoder Signal Type
Unlike incremental encoders, absolute encoders provide a unique code for every position, allowing them to output the absolute position directly. Every position is assigned a specific binary code (or Gray code), ensuring that the encoder can remember its position even during a power loss, and there is no need for a reset.
Working Principle of Absolute Encoders:
Absolute Encoding: Every position has a unique code representing the exact position, eliminating the need to calculate relative position.
Output Signal: The encoder outputs a fixed binary value to indicate the current position. Different encoding methods (such as binary or Gray code) can be used.
Power Loss Protection: Even if the power is cut, the encoder retains its position and directly resumes when powered on.
Absolute encoders are ideal for applications that require precise positioning and high reliability, commonly used in systems where high stability and accuracy are critical, such as CNC machines, robotics, and automation systems.
Comparison of Incremental Encoder vs. Absolute Encoder Signal Types
| Feature | Incremental Encoder | Absolute Encoder |
|---|---|---|
| Signal Output | Outputs pulse signals; one pulse per fixed rotation angle | Outputs a unique code for each position |
| Position Data | Provides relative position, requires an external counter | Provides absolute position data, no need for an external counter |
| Behavior After Power Loss | Position data is lost after power loss and needs to be reset | Position is retained after power loss, no need for re-zeroing |
| Application | Suitable for relative position, speed, and direction control, e.g., motor control | Suitable for high-precision and reliable position feedback, e.g., CNC machines, automation control |
| Cost | Lower cost | Higher cost |
| Complexity | Simple design, more economical | More complex design, offers more functions |
Which Encoder is Right for Your Needs?
Choosing between an incremental encoder and an absolute encoder depends on your application requirements. If you need to track relative position, speed, or direction without needing to preserve position data after a power loss, an incremental encoder is a more cost-effective choice with fast response time. On the other hand, if your application demands precise position feedback and the ability to retain position data after a power interruption, an absolute encoder provides higher reliability and accuracy.