A device for defining participants in a control system that controls a printing machine is provided. The control system includes a central computer and a number of participants which interact with the central computer in order to carry out processes. The participants are connected to one another via lines of a bus system. The lines of the bus system and the participants have respective plugs for connecting the lines of the bus system to the participants. The plugs of the lines of the bus system have reserved plug contacts which are provided with one or more galvanic links for defining the respective participants.