Synchronous Serial Interface — a clocked serial protocol used by most absolute encoders.

Do I need an absolute encoder for a precision servo?

Usually yes — modern servo drives expect absolute single-turn at minimum.

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Absolute vs Incremental Encoders — When to Use Which

Incremental encoders count pulses. Absolute encoders report position directly. The choice is rarely about resolution — it is about what happens at power-up.

Incremental

Pulses are accumulated against a reference. After power loss, position must be re-homed. Cheap, robust, infinite resolution (with interpolation).

Absolute

Position is encoded on the disc — single-turn (SSI, BiSS) or multi-turn (battery or gear). Power-on position is immediate.

Hoist drives

Always absolute multi-turn — you cannot re-home a loaded crane hook.

Conveyors

Incremental is fine — re-home at start-up against a proximity switch.

Safety

SIL 2 / PL d safety variants (Hübner) are available in both formats for overspeed and zero-speed monitoring.

FAQs

What is SSI?: Synchronous Serial Interface — a clocked serial protocol used by most absolute encoders.
Do I need an absolute encoder for a precision servo?: Usually yes — modern servo drives expect absolute single-turn at minimum.

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