Abstract: A system for controlling the connection and disconnection of a drive to a rotary cylinder of a printing press. The system comprises a position encoder coupled to a first cylinder of the press for generating at different instants in time two pulses when the first cylinder is rotated to increment its peripheral position by a predetermined amount. A validation gate receives the pulses and generates a single position increment pulse in response thereto. A counter, coupled to the validation gate, counts the position increment pulses and generates a revolution pulse every time the first cylinder effects a complete revolution with respect to a fixed reference point. The system also comprises a coupling unit in an operative relationship with the drive and with a second cylinder.