REDUNDANTER SERIENBUS

The connection of serial bus systems which are known per se, but have no system-integrated redundancy apparatus, to one another by means of bus lines of redundant design, is accomplished by a redundancy apparatus which can be connected upstream is connected between the bus communications interface of a bus subscriber and the redundant bus lines. In this case, during operation, transmission always takes place on all the bus lines, and a fault-free bus line is selected at the receiving end. The redundancy apparatus has an evaluation stage that determines criteria of a data stream other than the presence or absence of data for a period of time and the content of said data stream for selecting one of the bus lines as the receiving line based on the criteria.