Multi-tier, hierarchical fiber optic control network

• US 20040008721A1
• Filed: 07/10/2002
• Published: 01/15/2004
• Est. Priority Date: 07/10/2002
• Status: Active Grant

• Current Assignee: I/O Controls Corporation
• Original Assignee: I/O Controls Corporation
• Inventors: Ying, Jeffrey, Wang, Yongchang
• Granted Patent: US 6,965,560 B2
• Time in Patent Office: Days
• US Class Current: 370/460
• CPC Class Codes: H04L 12/422 Synchronisation for ring networks Time Division Multiplex ring networks, e.g. SDH/SONET H04J3/085
• CPC Class Codes: H04L 12/43 with synchronous transmission, e.g. time division multiplex [TDM], slotted rings
• CPC Class Codes: H04L 12/437 Ring fault isolation or reconfiguration for SDH/SONET ring networks H04J3/085

Abstract

A control network comprises multiple master nodes and multiple slave nodes, connected together in a loop configuration by at least one fiber optic cable. The master nodes share concurrent control over the network nodes by time multiplexing or other techniques. The control network may include two fiber optic rings which carry the same data simultaneously in opposite directions around the loop. A polling scheme may be used by the master nodes such that only one node transmits at a given time in both directions around the loop. The receiving node(s) propagate the transmissions and select between the transmissions based on time, error rate, or other factors. A hierarchical control network may be constructed with upper tier and lower tier fiber optic rings. Multiple master nodes may be used at any level of the ring, and some or all of the rings may include two fiber optics for bidirectional, redundant communication within the network.

Claims

1. A hierarchical master-slave control network, comprising:

a first-tier fiber optic ring;

a plurality of network nodes, including at least one first-tier master node and a plurality of first-tier slave nodes, in communication over said first-tier fiber optic ring;

a second-tier fiber optic ring; and

at least one second-tier slave node;

wherein one of said first-tier slave nodes operates as a second-tier master node with respect to said second-tier fiber optic ring and communicates with said at least one second-tier slave node over said second fiber optic ring.

2. The hierarchical master-slave control network of claim 1, wherein said plurality of network nodes comprises a plurality of first-tier master nodes sharing concurrent control over said first-tier slave nodes.

3. The hierarchical master-slave control network of claim 1, wherein communication over said first-tier fiber optic ring is carried out using time division multiplexing wherein each of said first-tier master nodes communicates with other network nodes during distinct, non-overlapping time portions.

4. The hierarchical master-slave control network of claim 3, wherein communications to or from said first-tier master nodes are time synchronized.

5. The hierarchical master-slave control network of claim 4, wherein transmissions by at least one of said first-tier master nodes are used by said network nodes to synchronize communications over said first-tier fiber optic ring.

6. The hierarchical master-slave control network of claim 3, wherein each of said first-tier master nodes operates as a first-tier slave node when not communicating with one of said first-tier slave nodes.

7. The hierarchical master-slave control network of claim 2, wherein each of said first-tier master nodes communicates with said first-tier slave nodes according to a polling scheme.

8. The master-slave control network of claim 2, wherein each of said first-tier master nodes controls a distinct, non-overlapping subset of said first-tier slave nodes.

9. The master-slave control network of claim 2, wherein upon failure of one of said first-tier master nodes, a different first-tier master node takes over some or all of the failed first-tier master node'"'"'s responsibilities.

10. The hierarchical master-slave control network of claim 1, further comprising:

a second second-tier fiber optic ring; and

at least one second-tier slave node connected to said second second-tier fiber optic ring;

wherein a second one of said first-tier slave nodes operates as a second-tier master node with respect to said second second-tier fiber optic ring and communicates over said second second-tier fiber optic ring with said at least one second-tier slave node connected to said second second-tier fiber optic ring.

11. The hierarchical master-slave control network of claim 1, further comprising:

a third-tier fiber optic ring; and

at least one third-tier slave node;

wherein one of said at least one second-tier slave nodes operates as a third-tier master node with respect to said third-tier fiber optic ring and communicates with said at least one third-tier slave node over said third fiber optic ring.

12. The hierarchical master-slave control network of claim 1, further comprising a second first-tier fiber optic ring providing a redundant communication path for said network nodes communicating over the other first-tier fiber optic ring.

13. The hierarchical master-slave control network of claim 12, wherein each of said network nodes communicates with other network nodes by transmitting identical data in opposite directions over both of the first-tier fiber optic rings.

14. The hierarchical master-slave control network of claim 13, wherein each intervening network node propagates received data to the next network node until the data reaches its destination.

15. A hierarchical master-slave control network, comprising:

a plurality of fiber optic rings including at least a first fiber optic ring and a second fiber optic ring; and

a plurality of network nodes, said plurality of network nodes comprising at least one first-tier master node connected to said first fiber optic ring, a plurality of first-tier slave nodes connected to said first fiber optic ring, and a plurality of second-tier slave nodes connected to said second fiber optic ring;

wherein one of said first-tier slave nodes is connected to said second fiber optic ring and is configured to operate as a master node with respect to said second-tier slave nodes.

16. The hierarchical master-slave control network of claim 15, wherein said plurality of network nodes comprises a plurality of first-tier master nodes sharing concurrent control over said first-tier slave nodes.

17. The hierarchical master-slave control network of claim 15, wherein each of said first-tier master nodes controls a distinct, non-overlapping subset of said first-tier slave nodes.

18. The hierarchical master-slave control network of claim 15, wherein each of said network nodes is substantially identical in hardware configuration.

19. The hierarchical master-slave control network of claim 15, wherein said first-tier slave node configured to operate as a master node with respect to said second-tier slave nodes comprises an uplink processor for communicating over said first fiber optic ring and a downlink processor for communicating over said second fiber optic ring.

20. The hierarchical master-slave control network of claim 19, wherein said first-tier slave node further comprises a volatile memory accessible to both said uplink processor and downlink processor, whereby said uplink processor and downlink processor may communicate with one another.

21. The hierarchical master-slave control network of claim 15, wherein said first fiber optic ring comprises a pair of optical fibers providing redundant communication paths for said network nodes.

22. The hierarchical master-slave control network of claim 21, wherein said second fiber optic ring comprises a second pair of optical fibers providing redundant communication paths for said second-tier slave nodes and said first-tier slave node configured to operate as the second-tier master node.

23. The hierarchical master-slave control network of claim 22, wherein each of said network nodes communicates with other nodes in the first fiber optic ring by transmitting identical data in opposite directions over both of the optical fibers of said first fiber optic ring, and wherein each of said second-tier slave nodes and said first-tier slave node configured to operate as the second-tier master node communicates with other nodes in the second fiber optic ring by transmitting identical data in opposite directions over both of the optical fibers of said second fiber optic ring

24. The hierarchical master-slave control network of claim 15, further comprising:

a third fiber optic ring; and

at least one third-tier slave node;

wherein one of said at least one second-tier slave nodes operates as a third-tier master node with respect to said third fiber optic ring and communicates with said at least one third-tier slave node over said third fiber optic ring.