A method and communication system for exchanging data between participants of a bus system

The invention relates to a method and to a communication system (1) for exchanging data between at least two users (2, 3, 4) that are interlinked via a bus system (5). The data are contained in messages that are transmitted by the users (2, 3, 4) via the bus system (5). Predetermined priorities are assigned to the individual messages. The aim of the invention is to increase the probability to a maximum that a message to be transmitted has a short latency time (t) and to guarantee, in the worst case, a maximum latency time (tmax). To this end, the priorities assigned to the messages are dynamically modified during operation of the bus system (5). Preferably, the set of all messages is subdivided into equivalence classes and every equivalence class is associated with a priority. During operation of the bus system (5), the priorities of the messages within one equivalence class and the priorities of the equivalence classes are dynamically modified.