Bridge for an industrial control system using data manipulation techniques

• US 7,107,358 B2
• Filed: 09/12/2001
• Issued: 09/12/2006
• Est. Priority Date: 09/12/2001
• Status: Active Grant

• Current Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Original Assignee: Rockwell Automation Technologies Incorporated (Allen-Bradley Co., Inc.)
• Inventors: Vasko, David A., Lenner, Joseph A.
• Primary Examiner(s): Maung, Zarni
• Assistant Examiner(s): PHILLIPS, HASSAN A
• Application Number:
  US09/951,163
• Publication Number:
  US 20030051053A1
• Time in Patent Office: 1,826 Days
• Field of Search: 709/230, 709/249, 709/250, 714/799, 714/819, 714/4
• US Class Current: 709/249
• CPC Class Codes: G05B 19/4185 characterised by the network communication
• CPC Class Codes: G05B 2219/31122 Bridge between networks
• CPC Class Codes: G05B 2219/31244 Safety, reconnect network automatically if broken
• CPC Class Codes: H04L 1/08 by repeating transmission, e.g. Verdan system H04L1/1858 and H04L1/189 take precedence
• CPC Class Codes: H04L 1/1607 Details of the supervisory signal
• CPC Class Codes: H04L 1/1848 Time-out mechanisms
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• CPC Class Codes: H04L 12/462 LAN interconnection over a bridge based backbone
• CPC Class Codes: H04L 69/08 Protocols for interworking; Protocol conversion
• CPC Class Codes: Y02P 90/02 Total factory control, e.g. smart factories, flexible manufacturing systems [FMS] or integrated manufacturing systems [IMS]

Abstract

A bridge usable in a highly reliable industrial control system provides an interface between a producer module transmitting redundant messages in accordance with a communication protocol and a consumer module receiving the messages in accordance with a different communication protocol. The bridge includes a first network interface receiving two messages from the producer, a microprocessor capable of converting the messages from the producer communication protocol to consumer communication protocol, and a second network interface transmitting the messages to the consumer. One of the messages is reversible altered with respect to the other message. The altered message is uninverted in the consumer module, and compared to the other message to ensure that no transmission errors have occurred.

Claims

1. A network safety control system comprising:

a bridge for connecting a first and second communication network, each with communication protocols;

a first communication module attached to the first communication network to transmit two messages on the first communication network to pass through the bridge to the second network, the two messages containing redundant data, the redundant data of a first message reversibly altered with respect to a second message;

a second communication module attached to the second communication network to receive the two messages on the second communication network and compare the data of the first and second messages to detect any alteration of the redundant data by the bridge; and

wherein errors in an operation of a standard bridge may be detected without modification of the bridge.

2. The safety control system of claim 1 wherein the reversible alteration of the data inverts bits of the data of the first message with respect to the second message.

3. The safety control system of claim 2 wherein the reversible alteration inverts all bits of the first message with respect to the second message.

4. The safety control system of claim 1 wherein the reversible alteration of the data adds data to the first message with bits inverted with respect to data added to the second message.

5. The safety control system of claim 1 wherein the reversible alteration of the first message does not modify the communication protocols.

6. The safety control system of claim 1 wherein the comparison of the data undoes the reversible modification of the first message and compares it to the second message.

7. The safety control system of claim 1 wherein the communication protocol is selected from the group consisting of Ethernet, DeviceNet, ControlNet, Fire Wire and Field Bus.

8. A safety control protocol executed on a first and second communication module communicating via messages sent on at least one network, the method comprising the steps of:

(a) transmitting first and second redundant messages from the first communication module to the second communication module through the network, data of at least one of the first and second redundant messages being reversibly altered;

(b) receiving the first and second messages at the second communication module to;

(i) compare the data of the first and second message to confirm that the data matches;

(ii) determine a time between transmission of the first and second messages and receiving of the first and second messages is less than a predetermined amount;

wherein errors caused by standard network hardware can be detected.

9. The safety control protocol of claim 8 wherein the network includes a bridge communicating between portions of the network having different network protocols.

10. The safety control protocol of claim 8 wherein the second communication module compares the data of the first and second message to detect data corruption by the standard network hardware.

11. The safety control protocol of claim 8 wherein the second communication module determines the time between transmission of the first and second data to detect one of data delay and data retransmission by the standard network hardware.

12. The safety control protocol of claim 8 wherein the communication module determines the time between transmission of the first and second data is determined by a time stamp of at least one of the first messages compared with a receipt time of at least one of the first and second messages.

13. The safety control system of claim 8 wherein the reversible alteration of the data inverts bits of the data of the first message with respect to the second message.

14. The safety control system of claim 13 wherein the reversible alteration inverts all bits of the first message with respect to the second message.

15. The safety control system of claim 8 wherein the reversible alteration of the data adds data to the first message with bits inverted with respect to data added to the second message.

16. The safety control system of claim 8 wherein the network uses a standard communication protocol and the reversible alteration of the first message does not modify the standard communication protocol.

17. The safety control system of claim 8 wherein the communication protocol is selected from the group consisting of Ethernet, DeviceNet, ControlNet, Fire Wire and Field Bus.

18. A method of detecting errors in a standard network bridge joining at least two communication networks without modification of the bridge, the method comprising:

sending a first and second message on a first communication network connected to the bridge, wherein at least one message is reversibly altered to pass through the bridge to the second network without modification of the bridge; and

comparing the first and second messages to detect corruption of the messages by the bridge.

19. The method of claim 18 wherein the reversible alteration of the data inverts bits of data of the first message with respect to the second message.

20. The method of claim 19 wherein the reversible alteration inverts all bits of the first message with respect to the second message.

21. The method of claim 18 wherein the reversible alteration of the data adds data to the first message with bits inverted with respect to data added to the second message.

22. The method of claim 18 wherein the reversible alteration of the first message does not modify the communication protocols.

23. The method of claim 18 wherein the comparison of the data undoes the reversible modification of the first message and compares it to the second message.

24. The method of claim 18 wherein the bridge joins communication networks using communication protocol selected from the group consisting of Ethernet, DeviceNet, ControlNet, Fire Wire and Field Bus.