a rotor spinning machine has a plurality of spinning stations , each of which comprises an opening roller and a draw - in roller for supplying sliver to the opening roller and each of which is equipped with control devices for individual drives of the draw - in rollers . the control devices each have a connection mechanism , to which an additional control card can be attached for producing effect or novelty yarn with predetermined effects . the control card comprises a processor , which meets the elevated computing power requirements for producing effect or novelty yarn and can be activated via a data bus system .