Method for transmitting data in a communication network of an industrial automation system and coupling communication device wherein in order to transmit data in a communication network of the industrial automation system, first data frames including control data for the automation system are transmitted by coupling communication devices of the communication network only within periodic first intervals of time, where second data frames, which are assigned to data streams comprising sequences of data frames, and/or third data frames, for the transmission of which no quality of service or a quality of service below a predefined threshold value is stipulated, are transmitted within periodic second intervals of time, the first intervals of time are subdivided into first and second sub-intervals, and where first data frames which are to be forwarded are inserted into a first and a second queue in alternating sub-intervals and are alternately removed from the queues for forwarding.