Method and system for communicating between devices

1. A network communication method, said network comprising first and second nodes, the method comprising:

transmitting a message from the first node to the second node, wherein the message comprises a data content portion and an identifying portion, wherein said identifying portion includes a first unique identifier corresponding to a time source which controls a time value at the first node;

receiving the transmitted message at the second node;

comparing the first unique identifier to a second unique identifier, wherein said second unique identifier corresponds to a time source which controls a time value at the second node; and

if the result of said comparison is positive, accepting the message for processing at the second node.

2. A method as claimed in claim 1 wherein the first node is synchronised to the time source which controls a time value at the first node, and/or wherein the second node is synchronised to the time source which controls a time value at the second node, and optionally wherein a node is deemed to be synchronised to a time source if a reference time used at the respective node matches a corresponding reference time at the time source to within a predetermined tolerance limit.

3. A method as claimed in claim 1 wherein the first and second nodes form part of a networked system and wherein said first unique identifier and/or said second unique identifier is unique within said networked system.

4. A method as claimed in claim 1 wherein said first unique identifier and/or said second unique identifier is a globally unique identifier.

5. A method as claimed in claim 1 wherein said comparison step is carried out at the second node.

6. A method as claimed in claim 1 wherein the result of the comparison is deemed to be positive if the first unique identifier is found to be identical to the second unique identifier, and optionally wherein the first unique identifier is found to be identical to the second unique identifier if the two identifiers match one another to within a predetermined threshold.

7. A method as claimed in claim 1 wherein the step of accepting the message for processing at the second node includes placing the message in a buffer for future processing.

8. A method as claimed in claim 1 wherein the step of accepting the message for processing at the second node comprises processing the message immediately once the result of the comparison has been deemed to be positive.

9. A method as claimed in claim 1 wherein the second node comprises a device having a repeating update period, and wherein the method further comprises processing the message at the second node at the beginning of a new update period.

10. A method as claimed in claim 1 wherein the second node comprises a device having a repeating update period, and wherein the method further comprises processing the message at the second node at a predetermined time after the beginning of a new update period.

11. A method as claimed in claim 1 wherein the transmitted message includes a processing instruction, wherein said processing instruction includes an indication of a processing time at which the second node should process the message if the result of the comparison is positive, and optionally wherein the second node comprises a device having a repeating update period and wherein the indication of a processing time at which the second node should process the message comprises a time interval from the beginning of an update period.

12. A method as claimed in claim 1 wherein the data content portion of the message includes a sampling indication, said sampling indication comprising a time at which sampled data within the data content portion was obtained, and optionally wherein said sampled data was obtained by any of: a sensor, a logging device, or a processor, and optionally said sampling indication comprising the step of using the sampling indication to obtain a data value for use by the second node using one of: interpolation or extrapolation.

13. A method as claimed in claim 1 wherein the first and second nodes communicate with one another using an Ethernet-based protocol.

14. A method as claimed in claim 1 wherein the first unique identifier and/or the second unique identifier comprises a unique network address for a device having a local clock, wherein said local clock comprises the time source which controls a time value at the respective node.

15. A method as claimed in claim 1 wherein the time source which controls a time value at the first node and/or the time source which controls a time value at the second node comprises a local clock at the first node or a local clock at the second node.

16. A method as claimed in claim 1 wherein the network comprises a third node and the time source which controls a time value at the first node and/or the time source which controls a time value at the second node comprises a local clock at the third node.

17. A method as claimed in claim 1 wherein the network further comprises a third node having a third unique identifier associated therewith, wherein said third unique identifier corresponds to a time source which controls a time value at the third node, and wherein said third unique identifier is different to the first unique identifier and/or to the second unique identifier.

18. A method as claimed in claim 1 wherein, if the result of said comparison is negative, the second node discards the message.

19. A method as claimed in claim 1 wherein the step of processing the message comprises copying data from the data content portion of the message to one or more data destinations at the second node.

20. A device arranged to communicate with one or more other devices on a network, wherein said device is configured to operate as a first node or as a second node on the network, the device including a controller configured to receive a transmitted message, the message comprising a data content portion and an identifying portion, said identifying portion including a first unique identifier corresponding to a time source which controls a time value at the first node; compare the first unique identifier to a second unique identifier, said second unique identifier corresponding to a time source which controls a time value at the second node; and if the result of said comparison is positive, accept the message for processing.

21. A device as claimed in claim 20 wherein the result of the comparison is deemed to be positive if the first unique identifier is found to be identical to the second unique identifier, and optionally wherein the first unique identifier is found to be identical to the second unique identifier if the two identifiers match one another to within a predetermined threshold.

22. A device as claimed in claim 20 wherein the controller is configured to place the message in a buffer for future processing.