Method for transmitting data in a communication network of an industrial automation system, in which - first data frames comprising control data for the automation system are transmitted by coupling communication devices of the communication network only within periodic first intervals of time, - the first intervals of time are each subdivided at least into a first and a second sub-interval, - the first intervals of time are each subdivided into a plurality of periodic first and second sub-intervals, first and second sub-intervals each alternately following one another, - an integer fraction of a time slot duration in the communication network having time-division multiplexing data transmission is stipulated as the duration for the first and second sub-intervals, - first data frames which are to be forwarded and are received by the coupling communication devices during the first sub-intervals are inserted into a first queue of the respective coupling communication device, - first data frames which are to be forwarded and are received by the coupling communication devices during the second sub-intervals are inserted into a second queue of the respective coupling communication device, - first data frames are removed from the first queues for forwarding during a second sub-interval respectively following their insertion, - first data frames are removed from the second queues for forwarding during a first sub-interval respectively following their insertion, - 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 by the coupling communication devices only within periodic second intervals of time, - the coupling communication devices are each operated in a transmission mode referred to as cut through. - first data frames comprising control data for the automation system are transmitted by coupling communication devices of the communication network only within periodic first intervals of time, - the first intervals of time are each subdivided at least into a first and a second sub-interval, - the first intervals of time are each subdivided into a plurality of periodic first and second sub-intervals, first and second sub-intervals each alternately following one another, - an integer fraction of a time slot duration in the communication network having time-division multiplexing data transmission is stipulated as the duration for the first and second sub-intervals, - first data frames which are to be forwarded and are received by the coupling communication devices during the first sub-intervals are inserted into a first queue of the respective coupling communication device, - first data frames which are to be forwarded and are received by the coupling communication devices during the second sub-intervals are inserted into a second queue of the respective coupling communication device, - first data frames are removed from the first queues for forwarding during a second sub-interval respectively following their insertion, - first data frames are removed from the second queues for forwarding during a first sub-interval respectively following their insertion, - 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 by the coupling communication devices only within periodic second intervals of time, - the coupling communication devices are each operated in a transmission mode referred to as cut through.