A method for the exchange of data in messages between at least two users which are connected by a bus system, the messages containing the data being transmitted by the users via the bus system, and each user containing a predefinable and/or ascertainable timing mark; a first user, in a function as timer, controls the messages as a function of time in such a way that it repeatedly transmits a reference message, which contains time information of the first user, via the bus at a specifiable time interval, and if the timing mark of the second user is reached without a reference message of the first user reaching the second user, the at least second user takes over the function of timer by transmitting its own reference message with its own time information via the bus system.