Importance

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Abstract

A multi-tier, master-slave control network has at least three data buses. A first-tier master node and a plurality of first-tier slave nodes are connected to a main data bus. One or more first-tier slave nodes are connected to secondary data buses. The secondary data buses are connected to second-tier slave nodes, and the first-tier slave node connected to the secondary data bus acts as a master node with respect to the secondary data bus. One or more second-tier slave nodes may be connected to tertiary data buses to provide another layer of control nesting. The tertiary data buses are connected to third-tier slave nodes, and the second-tier slave node connected to the tertiary data bus acts as a master node with respect to the tertiary data bus. A preferred embodiment of the control network provides redundant backup control for a master node at each level of the hierarchy in which the slave nodes connected to a particular data bus are provided with means for detecting a failure of the master node and for taking over for the master node when such a failure occurs. The master node and slave nodes each have an uplink transceiver and a downlink transceiver, with the downlink transceiver ordinarily isolated by switches from the common bus. The switches may be closed to connect the node to the same data bus as the uplink transceiver, allowing the node to become a master node with respect to that particular data bus.

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First Claim