Unlike for absolute encoders, in incremental rotary encoders the signals encode the movement of the rotor specifically in an incremental way in respect of the previous position. By processing such data, it is possible to determine the absolute position of the rotor, performing a search operation of reference at the end of each stroke. In the event of a power failure, the position data is lost. For its retrieval, a search of the reference point must be completed returning the rotor to the zero position.