An apparatus for controlling a plurality of appliances (5a, 5b, 5c) aboard a vehicle having a first data processing device that comprises a network interface that is designed and configured such that a network of a vehicle can be connected to the network interface and then, during operation, a bidirectional transmission of data is possible via the network interface between the first data processing device and appliances that are connected to this network, an input/output device having a screen, a graphics processor device that is connected to the screen and to the first data processing device and that, during operation, is controlled by the first data processing device to control the image displayed by the screen, a user interface module that is provided in the first data processing device and is adapted to implement, during operation, a graphical user interface that is displayed on the screen, and one or more separate second data processing devices (2b, 2c), wherein each of the one or more second data processing devices (2b, 2c) - comprises a network interface (3b, 3c) that is adapted such that a network (4b, 4c) of a vehicle can be connected to the network interface (3b, 3c) of the respective second data processing device (2b, 2c) and then, during operation, a bidirectional transmission of data is possible via the network interface (3b, 3c) of the respective second data processing device (2b, 2c) between the respective second data processing device (2b, 2c) and appliances (5b, 5c) that are connected to the respective network (4b, 4c), characterized in that the graphical user interface comprises a plurality of pages (10a, 10b, 10c) between which it is possible to change by operating the input/output device and that are each adapted for the input and/or output of data, each of the one or more separate second data processing device (2b, 2c) is connected to the first data processing device via a separate bidirectional data link (12b, 12c), via which, during operation, data is transmitted between the first and the respective second data processing device (2b, 2c), the user interface module is designed and configured such that the pages (10a, 10b, 10c) of the graphical user interface comprise, for each of the one or more second data processing devices (2b, 2c), at least one page (10b, 10c) on which, during operation, when the page is displayed on the screen, data are presented that have been transmitted from the respective second data processing device (2b, 2c) via the corresponding bidirectional data link (12b, 12c) to the first data processing device, and/or data can be input that are subsequently transmitted from the first data processing device via the corresponding bidirectional data link (12b, 12c) to the respective second data processing device (2b, 2c), and for each of the one or more second data processing devices (2b, 2c), the corresponding bidirectional data link (12b, 12c) is designed and configured such that it is only possible to transmit via it predefined data records (15, 16, 17) having data of predefined data types for display on said pages (10b, 10c) of the graphical user interface from the respective second data processing device (2b, 2c) to the first data processing device. - comprises a network interface (3b, 3c) that is adapted such that a network (4b, 4c) of a vehicle can be connected to the network interface (3b, 3c) of the respective second data processing device (2b, 2c) and then, during operation, a bidirectional transmission of data is possible via the network interface (3b, 3c) of the respective second data processing device (2b, 2c) between the respective second data processing device (2b, 2c) and appliances (5b, 5c) that are connected to the respective network (4b, 4c), characterized in that