Multi-protocol bus device

• US 20030056043A1
• Filed: 09/18/2001
• Published: 03/20/2003
• Est. Priority Date: 09/18/2001
• Status: Active Grant

• Current Assignee: Schneider Electric Systems USA, Inc. (Schneider Electric SE)
• Original Assignee: Invensys Systems Incorporated (Invensys PLC)
• Inventors: Kostadinov, Vladimir
• Granted Patent: US 7,032,045 B2
• Time in Patent Office: Days
• US Class Current: 710/104
• CPC Class Codes: H04L 12/40032 Details regarding a bus interface enhancer
• CPC Class Codes: H04L 69/18 Multiprotocol handlers, e.g. single devices capable of handling multiple protocols
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

In one general aspect, methods and devices for use with multiple communications protocols automatically determine which communications protocol to use when connected to a system bus. Signals transmitted on the system bus are monitored to determine what communications protocol the system bus is using. After determining which communications protocol the system is using, a compatible communications protocol is selected from one of several communications protocols stored in a device'"'"'s memory. As a result, a user may connect a device to the system bus without having to determine which communications protocol is used by the system bus. Furthermore, suppliers may stock a single type of device that is compatible with multiple communications protocols reducing overhead associated with stocking devices. In addition, a device may be switched between systems without regard to the communications protocol of the device or system.

Claims

1. A method implemented within an industrial control device for communicating on a bus, the method comprising:

receiving a signal transmitted on the bus;

determining whether the signal is specific to a communications protocol;

when the signal is specific, selecting the communications protocol corresponding to the specific signal; and

processing signals according to the selected communications protocol.

2. The method of claim 1 wherein determining whether the signal is specific to the communications protocol includes determining a content and a length of the received signal.

3. The method of claim 2 wherein the signal is determined to be specific to the communications protocol if the signal content in combination with the signal length is specific to the communications protocol.

4. The method of claim 2 further comprising storing a signal content, an associated signal length, and an indication of a communications protocol corresponding to the stored signal content and the associated signal length.

5. The method of claim 4 wherein determining whether the signal is specific to a communications protocol includes determining that the signal content and the signal length match the stored content and the associated length.

6. An industrial control device comprising:

a bus interface receiving a signal; and

a processor operable to determine whether the signal is specific to a communications protocol and, when the signal is specific, to select the communications protocol that corresponds to the specific signal, and to process signals according to the selected communications protocol.

7. The device of claim 6 wherein the processor determines that the signal is specific to a communications protocol by determining a content of the signal and a length of the signal.

8. The device of claim 7 wherein the processor determines whether the signal is specific to the communications protocol if the signal content in combination with the signal length is specific to the communications protocol.

9. The device of claim 7 further comprising a memory to store a signal content, an associated signal length, and an indication of a communications protocol that corresponds to the stored signal content and associated signal length.

10. The device of claim 9 wherein the processor determines if the signal content and the signal length match the stored content and the stored associated signal length and selects the corresponding communications protocol if a match is determined to exist.

11. A method implemented within an industrial control device for communicating on a bus, the method comprising:

monitoring signals transmitted on the bus;

determining that two or more monitored signals have a relationship;

selecting a communications protocol that corresponds to the relationship; and

processing signals according to the selected communications protocol.

12. The method of claim 11 wherein the relationship is that the two or more monitored signals form a sequence that is specific to a communications protocol.

13. The method of claim 12 wherein determining that two or more monitored signals have a relationship includes determining if the sequence formed by the two or more monitored signals matches a specific sequence of signals that corresponds to a communications protocol.

14. The method of claim 11 further comprising storing a specific sequence that corresponds to a communications protocol, wherein determining that two or more monitored signals have a relationship includes determining if the sequence of the two or more signals matches the stored specific sequence.

15. An industrial control device comprising:

a bus interface monitoring signals; and

a processor operable to determine that two or more monitored signals have a relationship, to select a communications protocol that corresponds to the relationship, and to process the signals according to the selected communications protocol.

16. The device of claim 15 wherein the relationship is that two or more signals form a sequence that is specific to a communications protocol.

17. The device of claim 15 wherein the processor determines that two or more monitored signals have a relationship if the sequence formed by the two or more monitored signals matches a sequence of signals that is specific to a communications protocol.

18. The device of claim 15 further comprising a memory to store a sequence of signals that is specific to a communications protocol wherein the processor determines if a sequence formed by the two or more monitored signal matches the stored specific sequence and selects the communications protocol if a match is determined.

19. A method implemented within an industrial control device for communicating on a bus using a first communications protocol or a second communications protocol, the method comprising:

selecting the first communications protocol;

determining checksums associated with a number of signals transmitted on the bus;

determining any errors using the checksums;

comparing the number of determined errors to a threshold;

selecting the second communications protocol if the threshold is exceeded; and

processing signals transmitted to the bus and signals received from the bus according to the selected communications protocol.

20. The method of claim 19 further comprising processing signals according to the first communications protocol if the threshold is not exceeded.

21. An industrial control device for communicating on a bus using a first communications protocol or a second communications protocol comprising:

a bus interface receiving signals; and

a processor selecting the first communications protocol, determining checksums associated with the received signals, determining any errors using the checksums, comparing a number of determined errors to a threshold, and selecting the second communications protocol if the threshold is exceeded.

22. The device of claim 21 wherein the processor processes a data signal transmitted or received on the bus according to the first communications protocol if the threshold in not exceeded.

23. A method implemented within an industrial control device for communicating on a bus, the method comprising:

monitoring signals transmitted on the bus;

determining a percentage of a type of signal;

comparing the percentage to a threshold associated with the type of signal;

determining if the threshold is exceeded;

selecting a communications protocol that corresponds to the type of signal if the threshold is exceeded; and

processing signals according to the selected communications protocol.

24. An industrial control device comprising:

a bus interface monitoring signals on a bus; and

a processor determining a percentage of a signal type, comparing the percentage to a threshold associated with the type of signal, determining if the threshold is exceeded, selecting a communications protocol that corresponds to the type of signal if the threshold is exceeded, and processing signals according to the selected communications protocol.