A digital printing device for the dynamic printing of a substrate web statically printed in a reel-fed printing press is disclosed. The digital printing device includes a position sensor which measures the substrate web for regulating a print position for the dynamic printing. The digital printing device is provided with a signal from a signal source of the reel-fed printing press. A position sensor control generates a synchronization signal and provides the synchronization signal to a digital printing head control. A speed signal transformer generates a feed signal and provides the feed signal to the digital printing head control. The digital printing head control activates the digital printing head dependent on the synchronization signal and the feed signal.