Abstract: The present invention provides, inter alia, a method for digital communication between at least one first node and a plurality of second nodes which are connected with the first node by a field bus. According to one aspect a highly effective presence detection scheme for checking the operational status of the second nodes by the first node is integratively combined with a message query for providing an effective first mode of digital communication between said nodes, which may be used very effectively to provide a communication channel which is independent of message priorities. According to another aspect the first mode of digital communication is combined with a second mode of digital communication which is based on message priorities of digital messages to be send by a respective second node to the first node. To advantage, a bitwise bus access arbitration mechanism may be used for implementing those modes of communication.

Abstract: The present invention provides, inter alia, a method for digital communication between at least one first node and a plurality of second nodes which are connected with the first node by a field bus. According to one aspect a highly effective presence detection scheme for checking the operational status of the second nodes by the first node is integratively combined with a message query for providing an effective first mode of digital communication between said nodes, which may be used very effectively to provide a communication channel which is independent of message priorities. According to another aspect the first mode of digital communication is combined with a second mode of digital communication which is based on message priorities of digital messages to be send by a respective second node to the first node. To advantage, a bitwise bus access arbitration mechanism may be used for implementing those modes of communication.

Abstract: An ambient condition monitoring system includes a common control unit, at least one primary communications bus and at least one supplemental communications bus. The control unit communicates with a plurality of supplemental units, which could include ambient condition detectors, using the primary communications bus in a normal operating environment. In the event of a sensed failure of the primary bus, or one of the supplemental units, communications can be automatically implemented using the supplemental communications bus.