Pre-setting of printing machines

In a printing machine including a plurality of printing stations each having at least one printing cylinder which can be activated for printing independently of printing cylinders of other stations, means for determining the angular offset of the printing cylinders of an upstream and a downstream printing station comprising means disposed at a predetermined location on each of the cylinders of the upstream and downstream printing stations for printing a reference mark on web or sheet material moved past the cylinders, optical scanning means disposed downstream of the printing cylinder of the downstream station for detecting reference marks printed by the two cylinders and providing respective output signals in response thereto, first transducer means having an output signal proportional to the length of material moved past the first transducer means, second transducer means having an output signal proportional to the angular rotation of a respective cylinder, first means coupled to receive the output signals of the scanning means and the second transducer means and in response thereto determining the relative angular position of the predetermined location of the downstream printing cylinder when a reference mark printed by the downstream printing cylinder is detected and for providing an output signal each time the predetermined location of the upstream printing cylinder rotates past an angular position corresponding to the relative angular position of the predetermined location of the downstream printing cylinder when the reference mark printed by the downstream printing cylinder was detected and second means coupled to receive the output signals of the first transducer means, the scanning means and the first means and providing a signal proportional to the distance travelled by the material between an output signal of the first means when the printing cylinder of the downstream printing station is not printing and when the printing cylinder of the upstream printing station is printing and the next reference mark printed by the printing cylinder of the upstream printing station detected by the optical scanning means.