The device for data transmission has a main station (3) and a number of terminals (1) and is provided with a device for coordinating operation in respective signaling data phases for downlink (42) and uplink (52) and corresponding useful signal data phases (41, 51). Each transmission frame (5) has a first data field (4211) that is fixed in length and is for required, time-critical, data and at least one other data field (4212) which is flexible in length and for only sporadically required data using various information elements (6), such as announcements of frequency changes, status information, additions to manufacture-specific information, warnings and/or information regarding the capabilities of the main station.