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The Synchronous Serial Interface (SSI) is an interface for absolute angle encoders (position encoders). You receive an absolute position information via a serial data transmission. The SSI interface has been developed by Max Stegmann GmbH and is used today by several manufacturers.

The interface is useful for application that require reliability and rigidity in industrial environment. Only two conductor pairs (for clock and data) are required. That makes the encoder very cheap. You can connect up to three encoders to one common clock.

Clock frequency, number of bits and data coding ( GrayCode or in    BinaryCode) is adjustable by software. A parity bit can be used for data safety.
Parameter overview see page Parameters for SSI Interface.


Transmission via SSI interface:

  1. measured value is saved
  2. send first data bit
  3. all data bits sent, monoflop starts
  4. monoflop back to start status