Abstract: A modularly assembled automation system includes a main unit with a plug-in bus port connector, a plurality of modules each with a plug-in bus connector and a plug-in signal connector, a backplane bus board in a layered structure with bus conductor tracks, a motherboard on which a plurality of connector elements are arranged, wherein the plug-in signal connectors of the modules are arranged in the connector elements and the connector elements are in electrical contact with conductor tracks of the motherboard, the bus conductor tracks and the layered structure of the backplane bus board are configured such that a layer stack forming the bus conductor tracks and core material contains features necessary for maintaining signal integrity of the signals on the backplane bus board and thus, with respect to the signal integrity of the signals on the backplane bus board, this is arranged separately on the motherboard.