absolute encoders with SSI or EnDat
Immediately after switching on the control unit, absolute encoders return the absolute position value without the machine moving. The absolute position is determined via optoelectronic scanning of several code tracks.
Single-turn encoders sense the absolute position within one revolution, while multiturn encoders also code the number of revolutions.
The transmission of the position information to the control unit is performed either via the SSI (synchronous serial interface) or via EnDat.