Backup control mechanism in a distributed control network
First Claim
1. A control network, comprising:
- a common bus;
a master node connected to the common bus; and
a plurality of slave nodes connected to the common bus in a loop configuration with said master node, each slave node comprisinga downlink transceiver isolated from the common bus when the slave node is in normal operation,an uplink transceiver connected to the common bus, whereby said slave node receives master-control signals over the common bus, anda failure mode detector;
wherein at least one slave node substitutes itself for the master node by connecting its downlink transceiver to the common bus when the slave node'"'"'s failure mode detector detects a failure of said master node, while said slave node'"'"'s uplink transceiver remains connected to the common bus such that the slave node thereafter receives master-control signals sent by its own downlink transceiver.
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Accused Products
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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Citations
24 Claims
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1. A control network, comprising:
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a common bus; a master node connected to the common bus; and a plurality of slave nodes connected to the common bus in a loop configuration with said master node, each slave node comprising a downlink transceiver isolated from the common bus when the slave node is in normal operation, an uplink transceiver connected to the common bus, whereby said slave node receives master-control signals over the common bus, and a failure mode detector; wherein at least one slave node substitutes itself for the master node by connecting its downlink transceiver to the common bus when the slave node'"'"'s failure mode detector detects a failure of said master node, while said slave node'"'"'s uplink transceiver remains connected to the common bus such that the slave node thereafter receives master-control signals sent by its own downlink transceiver. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method for providing redundant backup master control in a control network which comprises a master node and a plurality of slave nodes connected in a loop configuration, said method comprising the steps of:
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sending messages from the master node to the slave nodes over a common bus; receiving the messages from the master node at each slave node; monitoring at each slave node an amount of time from receipt of the most recent message from the master node; substituting one of the slave nodes for the master node when said amount of time reaches a predetermined failure mode waiting period, said substitute master node thereafter concurrently functioning as both a slave node and a master node; sending messages from said substitute master node to the slave nodes, including itself, over said common bus; and receiving the messages from said substitute master node at each slave node, including itself. - View Dependent Claims (10, 11, 12)
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13. A multi-bus control network with redundant backup control, said multi-bus control network comprising:
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a first bus; a second bus; a first-tier master node connected to the first bus; a plurality of first-tier slave nodes connected to the first bus in a loop configuration, each first-tier slave node comprising a first-tier slave node downlink transceiver isolated from the first bus when the first-tier slave node is in normal operation, a first-tier slave node uplink transceiver connected to the first bus, whereby said first-tier slave node receives control message signals over the first bus, and a first-tier slave node failure mode detector; a plurality of second-tier slave nodes connected to the second bus in a loop configuration, each of said second-tier slave nodes comprising a second-tier slave node downlink transceiver isolated from the second bus when the second-tier slave node is in normal operation, a second-tier slave node uplink transceiver connected to the second bus, whereby said second-tier slave node receives control message signals over the second bus, and a second-tier slave node failure mode detector; wherein at least one first-tier slave node substitutes itself for the first-tier master node by connecting its first-tier slave node downlink transceiver to the first bus when the first-tier slave node'"'"'s first-tier slave node failure mode detector detects a failure of said first-tier master node; wherein at least one first-tier slave node has its first-tier downlink transceiver connected to the second bus and functions as a second-tier master node with respect to the second-tier slave nodes; and wherein at least one second-tier slave node substitutes itself for the second-tier master node by connecting its second-tier slave node downlink transceiver to the second bus when the second-tier slave node'"'"'s second-tier slave node failure mode detector detects a failure of said second-tier master node. - View Dependent Claims (14, 15, 16, 17, 18, 19, 20)
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21. A multi-tier control network, comprising:
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a first common bus; a first-tier master node connected to the first common bus; a plurality of first-tier slave nodes connected to the first common bus, each of said first-tier slave nodes capable of receiving commands from said first-tier master node over the first common bus; a second common bus, said second common bus connected to one of said first-tier slave nodes acting as a second-tier master node; and a plurality of second-tier slave nodes connected to the second common bus, each of said second-tier slave nodes capable of receiving commands from said first-tier slave node acting as a second-tier master node; said first-tier slave node acting as a second-tier master node comprising a failure mode detector whereby said first-tier slave node substitutes itself for said first-tier master node in the event of a failure by said first-tier master node, said first-tier slave node connecting said first common bus and said second common bus together to form a single common bus in the event of said failure by said first-tier master node. - View Dependent Claims (22, 23, 24)
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Specification