Bridge for an industrial control system using data manipulation techniques

• US 20060271709A1
• Filed: 08/03/2006
• Published: 11/30/2006
• 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.
• Granted Patent: US 7,721,004 B2
• Time in Patent Office: Days
• 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 inter-network interface device 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 inter-network interface device 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:

an inter-network interface device 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 inter-network interface device 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 inter-network interface device; and

whereby errors in an operation of a standard inter-network interface device may be detected without modification of the inter-network interface device.

2. The safety control system of claim 1 wherein the inter-network interface device is selected from the group consisting of a bridge and a router.

3. 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.

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

5. 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.

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

7. 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.

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

9. A communication module for use in a network safety control system including at least a first and second communication network each with communication protocols, the first and second communications networks joined by an inter-network interface device to allow communication therebetween, the communication module comprising:

an interface adapted to attach the communication module to one of the first and second communication networks

processing circuitry communicating with the interface to transmit two messages on the attached communication network to pass through the inter-network interface device 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 so that a corresponding second communication module attached to the other of the first and second communication networks may receive the two messages on the other communication network and compare the data of the first and second messages to detect any alteration of the redundant data by the inter-network interface device; and

whereby errors in an operation of a standard inter-network interface device may be detected without modification of the inter-network interface device.

10. The communication module of claim 9 wherein the reversible alteration of the data inverts bits of the data of the first message with respect to the second message.

11. The communication module of claim 10 wherein the reversible alteration inverts all bits of the first message with respect to the second message.

12. The communication module of claim 9 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.

13. The communication module of claim 9 wherein the reversible alteration of the first message does not modify the communication protocols of the first and second communication networks.

14. The communication module of claim 9 wherein the comparison of the data undoes the reversible modification of the first message and compares it to the second message.

15. The communication module of claim 9 wherein the communication protocols are selected from the group consisting of Ethernet, DeviceNet, ControlNet, Fire Wire and Field Bus.