Input/output module for a bus system, comprising: - a first DC voltage supply and a second DC voltage supply, - a physical interface, a first transformer, a second transformer, a first inductive subassembly, a second inductive subassembly, a first capacitive subassembly, a second capacitive subassembly, a first switching device and a second switching device, - a socket having five contact cups, - the five contact cups each comprising an electrical contact, - the first DC voltage supply being able to be electrically connected to a respective electrical contact of two of the five contact cups via the first inductive subassembly by means of the first switching device, - the second DC voltage supply being able to be electrically connected to a respective electrical contact of two others of the five contact cups via the second inductive subassembly by means of the second switching device, - the physical interface being electrically connected to the respective electrical contacts of two of the five contact cups via the first transformer and via the first capacitive subassembly in order to apply a first differential data signal to the two electrical contacts of the two of the five contact cups, - the physical interface being electrically connected to the respective electrical contacts of the two others of the five contact cups via the second transformer and via the second capacitive subassembly in order to apply a second differential data signal to the two electrical contacts of the other two of the five contact cups, and - a measuring device for detecting a connector of a four-wire data cable, which measuring device is configured to detect, when a connector is inserted into the socket, whether the connector comprises four or five electrical contact pins which are each plugged into one of the contact cups and are electrically connected to the respective electrical contact of the contact cups, - the measuring device being configured to close the first and second switching devices (507, 509) only when five electrical contact pins are detected in order to apply a respective supply voltage of the two DC voltage supplies (34, 35) to the corresponding plugged contact pins of the connector plugged into the socket via the respective electrical contacts of the contact cups. - a first DC voltage supply and a second DC voltage supply, - a physical interface, a first transformer, a second transformer, a first inductive subassembly, a second inductive subassembly, a first capacitive subassembly, a second capacitive subassembly, a first switching device and a second switching device, - a socket having five contact cups, - the five contact cups each comprising an electrical contact, - the first DC voltage supply being able to be electrically connected to a respective electrical contact of two of the five contact cups via the first inductive subassembly by means of the first switching device, - the second DC voltage supply being able to be electrically connected to a respective electrical contact of two others of the five contact cups via the second inductive subassembly by means of the second switching device, - the physical interface being electrically connected to the respective electrical contacts of two of the five contact cups via the first transformer and via the first capacitive subassembly in order to apply a first differential data signal to the two electrical contacts of the two of the five contact cups, - the physical interface being electrically connected to the respective electrical contacts of the two others of the five contact cups via the second transformer and via the second capacitive subassembly in order to apply a second differential data signal to the two electrical contacts of the other two of the five contact cups, and - a measuring device for detecting a connector of a four-wire data cable, which measuring device is configured to detect, when a connector is inserted into the socket, whether the connector comprises four or five electrical contact pins which are each plugged into one of the contact cups and are electrically connected to the respective electrical contact of the contact cups, - the measuring device being configured to close the first and second switching devices (507, 509) only when five electrical contact pins are detected in order to apply a respective supply voltage of the two DC voltage supplies (34, 35) to the corresponding plugged contact pins of the connector plugged into the socket via the respective electrical contacts of the contact cups.