A control device is provided that includes a plate and a control unit. The control unit has a rotary unit designed as a transmitter unit and a receiver unit. The transmitter unit has a top surface and a bottom side, wherein a base is formed on the bottom side in a center region and a first magnetizable element or a first magnet for positioning the transmitter unit at a predefined position over the receiver unit is arranged in the center region. In a rest position the transmitter unit rests with the base on the plate and the axis of rotation extends essentially parallel to the normal of the plate, or the transmitter unit is tilted into an operating position such that the base rests only partially on the plate and the axis of rotation is tilted relative to the normal of the plate.