The core feature of absolute encoders

The core feature of absolute encoders lies in their ability to directly output absolute position information through unique encoding, without relying on reference points or continuous counting. Below are the key distinguishing points:

**Position Information Output Method**  

- **Absolute Encoder**: Uses a code disc engraved with unique binary codes (e.g., Gray code) to directly output absolute coordinate values. Each mechanical position corresponds to a unique digital code. For example, a 12-bit absolute encoder provides 2^12 = 4096 unique position points.  

- **Incremental Encoder**: Outputs only pulse signals (A/B phase). Requires an external device to accumulate pulse counts for calculating relative displacement. Position data is lost after power loss and requires re-referencing.  

**Power-Loss Memory Capability**  

- **Absolute**: Retains position information after power loss, eliminating the need for recalibration. For example, in machine tools or aerospace equipment, sudden power outages do not result in position data loss.  

- **Incremental**: Requires external memory devices to save positions or re-establish a zero point after power restoration.  

**Structure and Complexity**  

- **Absolute**: Features code discs with multiple optical channel markings (e.g., 2, 4, 8, 16 tracks), resulting in complex structures and higher costs. For instance, multi-turn absolute encoders use gear assemblies to record multi-revolution positions, enabling measurements beyond 360°.  

- **Incremental**: Requires only a single row of markings, offering simple structures and lower costs.  

**Application Scenarios**  

- **Absolute**: Suitable for high-precision, high-reliability applications such as robotic arms, aerospace systems, and medical instruments.  

- **Incremental**: Commonly used in cost-sensitive scenarios like speed measurement and simple positioning (e.g., motor speed monitoring).  

**Signal Output Type**  

- **Absolute**: Typically uses serial communication (e.g., SSI interface) or bus protocols for digital signal transmission.  

- **Incremental**: Outputs analog pulse signals (A/B/Z phases), requiring external counters for processing.  

**Summary**: The core advantages of absolute encoders are their **direct output of unique position codes** and **data retention during power loss**, making them ideal for reliability-critical and high-precision applications. Incremental encoders, relying on pulse counting, suit cost-sensitive use cases. Practical selection should consider precision requirements, budget, and system complexity.