Bus monitor unit

A central node for a data bus system having a bus monitor unit with a receiver for registering the signals on the data bus, and evaluation means that detect a faulty communication, and at least temporarily block communication by the user causing the faulty communication, or compensate an incorrect communication triggered by interference influences. The bus monitor unit is integrated into the central bus node and a plurality of bus branches of different users are combined at the central node so that the bus monitor unit can check a plurality of users for incorrect communication. In addition, a diagnostic unit is integrated into the central node, for monitoring the regularity of retriggering of the bus monitor in response to time patterns of the data bus, so that the monitor unit can be deactivated in the absence of retriggering.