Data transmission in a segmented communication network

A method for data transmission in a communication network that is split into a plurality of segments including a transmission medium and at least one slave subscriber, each segment being provided with a segment master, and two respective adjacent segments being connected by a transition region, where a segment master and a slave subscriber, which is situated in the segment of the segment master or in a transition region connecting this segment to an adjacent segment, communicate via the transmission medium of the segment of the segment master, where the segment master assigns the slave subscriber at least one transmission time interval for sending messages, so that transmission time intervals assigned by the segment master do not overlap, and where a slave subscriber within a transition region checks, before sending a message, whether the transmission media of both segments connected by the transition region are free to send a message.