Importance

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Abstract

A multi-tier, master-slave control network having redundant backup for a master node in which the slave nodes are provided with means for detecting a failure of the master node and for taking over for the master node in such circumstances. The master node and slave nodes are connected to a common bus. Each of the slave nodes has an uplink transceiver and a downlink transceiver, with the downlink transceiver ordinarily isolated by switches from the common bus. Each of the slave nodes has a timer programmed with a separate failure mode detection time period. When a slave mode fails to receive control messages from the master node for a period exceeding its programmed failure mode detection time period, the slave node takes over for the master node. Because each slave node has a separate failure mode detection time period, a priority is established in which the slave nodes will take over for the master node, and redundant master backup control is provided. A preferred embodiment of the control network has multiple buses, one bus for each tier, and each bus has a master node and a plurality of slave nodes, with each of the slave nodes capable of taking over for the master node on the slave node's particular bus.

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First Claim