A transmit mode performs indirect synchronization with a master node for accessing a medium, in a synchronous communications network comprising a plurality of slave nodes capable of accessing the medium during access time slots. The indirect synchronization includes receiving at least one frame coming from at least one of the slave nodes of the network. From each frame received, synchronization information pertaining to a level of synchronization of the slave node having sent the frame is obtained, the level of synchronization of the slave node being relative to the master node. A reference node is selected from among the at least one of the slave nodes from which at least one frame has been received, as a function of the pieces of synchronization information, the transmit node being indirectly synchronized with the master node via the reference node.