Method for transmitting data in an automation communication network having at least one distribution node (CU1, CU2, CU3, CU4) that has multiple input/output interfaces that are each connected at least to one network segment (N1, N2, N3, N4, N5, N6), wherein a first subscriber (T1) is arranged in a first network segment (N1) and a second subscriber (T2) is arranged in a second network segment (N2), wherein a data interchange takes place between the first subscriber (T1) and the second subscriber (T2) in the form of messages, characterized in that the messages are realised as scheduled messages, which are distinguished by a firm transmission time for the transmission by the at least one distribution node (CU1, CU2, CU3), and as unscheduled messages, which are distinguished without a firm transmission time for the transmission by the at least one distribution node (CU1, CU2, CU3), wherein the unscheduled messages each have associated control data for the distribution node (CU1, CU2, CU3, CU4), and the control data comprise a data field (D-CU1, D-CU2, D-CU3, D-CU1*, D-CU2*, D-CU3*) that the distribution node (CU1, CU2, CU3, CU4) processes, wherein the distribution node (CU1, CU2, CU3, CU4) is designed to receive an unscheduled message on an input/output interface and to send it on a further input/output interface, wherein the distribution node (CU1, CU2, CU3, CU4) is designed to ascertain a transmission time duration for the transmission of the unscheduled message, wherein the distribution node (CU1, CU2, CU3, CU4) is designed to ascertain a time window, remaining before a transmission of a next scheduled message, of the input/output interface, which is intended as the transmission interface for the unscheduled message, and to check whether the unscheduled message is transmittable with the transmission time duration within the remaining time window, wherein the distribution node (CU1, CU2, CU3, CU4) transmits the unscheduled message via the transmission interface if the unscheduled message is transmittable with the transmission time duration within the remaining time window of the transmission interface before transmission of the next scheduled message, wherein the distribution node (CU1, CU2, CU3, CU4) enters first message information in the data field (D-CU1, D-CU2, D-CU3, D-CU1*, D-CU2*, D-CU3*) of the control data of the unscheduled message before transmitting the unscheduled message, wherein the first message information indicates that the unscheduled message is transmitted completely, and wherein the distribution node (CU1, CU2, CU3, CU4) fragments the unscheduled message if the message is not transmittable with the transmission time duration within the remaining time window of the transmission interface before transmission of the next scheduled message, wherein the distribution node (CU1, CU2, CU3, CU4) enters second message information in the data field D-CU1, D-CU2, D-CU3, D-CU1*, D-CU2*, D-CU3*) of the control data of the unscheduled message before transmitting the unscheduled message, wherein the second message information indicates that the message is fragmented and comprises an additional distribution node identification that is used to distinguish between the individual distribution nodes (CU1, CU2, CU3, CU4) in the automation communication network. <EOS>