Method for initializing a system comprising a basic module and a first and a second expansion module (16a-16c), wherein the first and second expansion modules (16a, 16b) are electrically detachably coupled to the basic module and each have one or more electrical peripheral interfaces (48, 50, 60), wherein the method comprises: the system performing an initialization routine, wherein the initialization routine comprises: interrogating the first and second expansion modules (16a-16c) with regard to description data; storing a data structure comprising the requested description data; and providing the data structure to a configuration device; characterized in that the description data comprise characteristic data of the electrical peripheral interfaces (48, 50, 60) and an identification of the first and second expansion modules (16a-16c); and the method further comprises: checking whether one of the interrogated expansion modules (16a-16c) has a peripheral interface that is intended and designed to send and receive data packets via a data line connected to the peripheral interface: if one of the interrogated expansion modules (16a-16c) has a peripheral interface that is intended and designed to send and receive data packets via a data line connected to the peripheral interface, interrogating the peripheral interface with regard to devices (32, 34) with which data can be interchanged by means of the sending and/or receiving of data packets by way of the peripheral interface; and storing device information about the devices (32, 34) with which data can be interchanged by way of the peripheral interface by means of the sending and/or receiving of data packets in the data structure. the system performing an initialization routine, wherein the initialization routine comprises: interrogating the first and second expansion modules (16a-16c) with regard to description data; storing a data structure comprising the requested description data; and providing the data structure to a configuration device; characterized in that the description data comprise characteristic data of the electrical peripheral interfaces (48, 50, 60) and an identification of the first and second expansion modules (16a-16c); and the method further comprises: checking whether one of the interrogated expansion modules (16a-16c) has a peripheral interface that is intended and designed to send and receive data packets via a data line connected to the peripheral interface: if one of the interrogated expansion modules (16a-16c) has a peripheral interface that is intended and designed to send and receive data packets via a data line connected to the peripheral interface, interrogating the peripheral interface with regard to devices (32, 34) with which data can be interchanged by means of the sending and/or receiving of data packets by way of the peripheral interface; and storing device information about the devices (32, 34) with which data can be interchanged by way of the peripheral interface by means of the sending and/or receiving of data packets in the data structure. interrogating the first and second expansion modules (16a-16c) with regard to description data; storing a data structure comprising the requested description data; and providing the data structure to a configuration device; characterized in that the description data comprise characteristic data of the electrical peripheral interfaces (48, 50, 60) and an identification of the first and second expansion modules (16a-16c); and the method further comprises: checking whether one of the interrogated expansion modules (16a-16c) has a peripheral interface that is intended and designed to send and receive data packets via a data line connected to the peripheral interface: if one of the interrogated expansion modules (16a-16c) has a peripheral interface that is intended and designed to send and receive data packets via a data line connected to the peripheral interface, interrogating the peripheral interface with regard to devices (32, 34) with which data can be interchanged by means of the sending and/or receiving of data packets by way of the peripheral interface; and storing device information about the devices (32, 34) with which data can be interchanged by way of the peripheral interface by means of the sending and/or receiving of data packets in the data structure. if one of the interrogated expansion modules (16a-16c) has a peripheral interface that is intended and designed to send and receive data packets via a data line connected to the peripheral interface, interrogating the peripheral interface with regard to devices (32, 34) with which data can be interchanged by means of the sending and/or receiving of data packets by way of the peripheral interface; and storing device information about the devices (32, 34) with which data can be interchanged by way of the peripheral interface by means of the sending and/or receiving of data packets in the data structure.