There is described a node device of a serial bus system, a bus system with a node device of this type, and an input/output card. In serial bus system, in which individual node devices can have only a limited address space, and in which a number of input/output cards can be connected in order to control and/or regulate an item of external peripheral equipment, limitations arise for the individual input/output cards with regard to the available address space. Normally, the input/output cards, which are connected to the node device, are required to divide the address space of the node device among each other. In order to rectify this problem, the invention provides that a node device of a serial bus system, which has slots for input/output cards, is additionally equipped with a splitter for duplicating a received bus signal and for injecting the duplicated bus signal into another data line, the additional data line serially connecting the node device to input/output cards connected via the slots.