Bus guardian for monitoring and controlling access to data bus, has serial peripheral interface approving access of controller to data bus only when communication offers normal functioning of controller

摘要

The unit has an interface e.g. serial peripheral interface (SPI) (18) for realizing a query response communication with a communication controller (6). The interface approves the access of the communication controller to a data bus only when the query response communication offers normal functioning of the communication controller. The bus guardian monitors whether a number of received, decoded and synchronization messages is large and/or same of quorum, within the communication. An independent claim is also included for a subscriber of a communication system including a data bus.