Bus system, comprising: - a data cable having two wire pairs (175, 177; 179, 181), - wherein the data cable comprises a first portion of an electrical plug connection, the first portion comprising four first electrical contact elements (185, 187, 189, 191), wherein - the four first electrical contact elements are each electrically connected to one of the wires (175, 177, 179, 181) of the two wire pairs, - an input/output module, - wherein the input/output module has a first DC voltage supply, a second DC voltage supply, a physical interface, a first transformer, a second transformer, a first inductive assembly, a second inductive assembly, a first capacitive assembly, a second capacitive assembly and a second portion that is complementary to the first portion of the electrical plug connection, the second portion comprising four second electrical contact elements (123, 125, 127, 129), - wherein the four second electrical contact elements each comprise an electrical contact, - wherein the first DC voltage supply is connected to a respective electrical contact of two of the four second electrical contact elements via the first inductive assembly, - wherein the second DC voltage supply is connected to a respective electrical contact of two others of the four second electrical contact elements via the second inductive assembly, - wherein the physical interface is connected to the respective electrical contacts of the two of the four second electrical contact elements via the first transformer and via the first capacitive assembly in order to apply a first differential data signal to the two electrical contacts of the two of the four second electrical contact elements, - wherein the physical interface is connected to the respective electrical contacts of the two others of the four second electrical contact elements via the second transformer and via the second capacitive assembly in order to apply a second differential data signal to the two electrical contacts of the two others of the four second electrical contact elements, characterized in that - the data cable has a communication subscriber, - wherein the input/output module comprises a microcontroller unit, - wherein the microcontroller unit is configured to communicate with the communication subscriber of the data cable, - wherein the microcontroller unit is configured to actuate the first and second DC voltage supplies (107, 109) such that they apply a respective DC voltage to the applicable electrical contacts of the four second electrical contact elements only if the microcontroller unit has been able to communicate with the communication subscriber of the data cable, so that a respective DC voltage is not applied in the absence of the communication and/or in the absence of a communication subscriber in the data cable. - a data cable having two wire pairs (175, 177; 179, 181), - wherein the data cable comprises a first portion of an electrical plug connection, the first portion comprising four first electrical contact elements (185, 187, 189, 191), wherein - the four first electrical contact elements are each electrically connected to one of the wires (175, 177, 179, 181) of the two wire pairs, - an input/output module, - wherein the input/output module has a first DC voltage supply, a second DC voltage supply, a physical interface, a first transformer, a second transformer, a first inductive assembly, a second inductive assembly, a first capacitive assembly, a second capacitive assembly and a second portion that is complementary to the first portion of the electrical plug connection, the second portion comprising four second electrical contact elements (123, 125, 127, 129), - wherein the four second electrical contact elements each comprise an electrical contact, - wherein the first DC voltage supply is connected to a respective electrical contact of two of the four second electrical contact elements via the first inductive assembly, - wherein the second DC voltage supply is connected to a respective electrical contact of two others of the four second electrical contact elements via the second inductive assembly, - wherein the physical interface is connected to the respective electrical contacts of the two of the four second electrical contact elements via the first transformer and via the first capacitive assembly in order to apply a first differential data signal to the two electrical contacts of the two of the four second electrical contact elements, - wherein the physical interface is connected to the respective electrical contacts of the two others of the four second electrical contact elements via the second transformer and via the second capacitive assembly in order to apply a second differential data signal to the two electrical contacts of the two others of the four second electrical contact elements, - the data cable has a communication subscriber, - wherein the input/output module comprises a microcontroller unit, - wherein the microcontroller unit is configured to communicate with the communication subscriber of the data cable, - wherein the microcontroller unit is configured to actuate the first and second DC voltage supplies (107, 109) such that they apply a respective DC voltage to the applicable electrical contacts of the four second electrical contact elements only if the microcontroller unit has been able to communicate with the communication subscriber of the data cable, so that a respective DC voltage is not applied in the absence of the communication and/or in the absence of a communication subscriber in the data cable.