Communication system for a control system over Ethernet and IP networks

• US 7,162,510 B2
• Filed: 04/10/2002
• Issued: 01/09/2007
• Est. Priority Date: 03/16/1998
• Status: Expired due to Term

• Current Assignee: Schneider Automation Incorporated (Schneider Electric SE)
• Original Assignee: Schneider Automation Incorporated (Schneider Electric SE)
• Inventors: Jammes, Francois
• Primary Examiner(s): Etienne; Ario
• Assistant Examiner(s): JACOBS, LASHONDA T
• Application Number:
  US10/120,037
• Publication Number:
  US 20020194365A1
• Time in Patent Office: 1,735 Days
• Field of Search: 709/208, 709/209
• US Class Current: 709/203
• CPC Class Codes: H04L 12/403 with centralised control, e.g. polling
• CPC Class Codes: H04L 2012/40228 Modbus
• CPC Class Codes: H04L 2012/4026 Bus for use in automation systems
• CPC Class Codes: H04L 41/00 Arrangements for maintenance, administration or management of data switching networks, e.g. of packet switching networks
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/13 in a LAN segment, e.g. ring or bus
• CPC Class Codes: H04L 47/2433 Allocation of priorities to traffic types
• CPC Class Codes: H04L 67/12 specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks
• CPC Class Codes: H04L 67/51 Discovery or management thereof, e.g. service location protocol [SLP] or web services
• CPC Class Codes: H04L 67/55 Push-based network services
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A communication system is provided for communication within a control system. The communication system has a plurality of simple devices connected to an intra-level communications network, each simple device being adapted to directly exchange data with the other simple devices. The communications system also has at least one intelligent device connected to the intra-level communications network, each intelligent device being adapted to directly exchange data with each simple device on the intra-level communications networks. The communication system can have a plurality of intra-level communications networks. The intra-level communications networks can be directly be connected by an intra-level core connector or by an inter-level core connector through an inter-level network of the intelligent devices.

Claims

1. A method of communicating within a connectionless network having a plurality of devices operably connected via Ethernet, the method comprising the steps of:

providing a first intra-level cluster of devices, the first intra-level cluster of devices including a first intelligent device and a first plurality of simple devices;

publishing a first data frame via user datagram protocol (UDP) and internet protocol (IP), the first data frame being published by a first one of the first intra-level cluster of devices;

associating a first refreshment status with the published first data frame, the first refreshment status corresponding to the time of publication of the first data frame onto the network;

receiving the published first data frame, the first data frame being received by a second one of the first intra-level cluster of devices; and

,

providing a first promptness status responsive to the second one of the first intra-level cluster of devices, the first promptness status being associated with the received first data frame and indicative of the time of receipt of the published first data frame wherein the second one of the first intra-level cluster of devices being capable of determining the duration of the published first data frame;

setting a timer upon one of publication of the first data frame and receipt of the published first data frame;

maintaining one of the refreshment status and the promptness status as valid until the timer expires;

providing a first inter-level cluster of devices, the first inter-level cluster of devices including the first intelligent device and a second intelligent device;

publishing a second data frame via user datagram protocol (UDP) and internet protocol (IP), the second data frame being published by the first intelligent device;

associating a second refreshment status with the published second data frame, the second refreshment status corresponding to the time of publication of the second data frame onto the network;

receiving the published second data frame, the second data frame being received by the second intelligent device;

providing a second promptness status responsive to the second intelligent device, the second promptness status being associated with the received second data frame and indicative of the time of receipt of the published second data frame wherein the second intelligent device being capable of determining the duration of the published second data frame; and

,

providing a second intra-level cluster of devices, the second intra-level cluster of devices including the second intelligent device and a second plurality of simple devices.

2. The method of claim 1 further comprising:

broadcasting a network clock signal to the plurality of devices on the connectionless network wherein the first refreshment status and the first promptness status are responsive to the network clock.

3. The method of claim 2 further comprising:

synchronizing a local clock of each of the plurality of devices with the broadcasted network clock signal.

4. The method of claim 3 wherein the publishing of the first data frame is cyclical, the cyclical publication of the first data frame being responsive to the local clock of the first one of the first intra-level cluster of devices.

5. The method of claim 1 wherein the publishing of the first data frame comprises IP multicasting for transmitting the first data frame to a predetermined group of network devices selected from the plurality of network devices.

6. The method of claim 5 further comprising:

dynamically defining the predetermined group of network devices for receiving the first data frame via IP multicasting.

7. The method of claim 1 wherein the publishing of the first data frame is responsive to an event.

8. The method of claim 1 further comprising configuring the first one of the first intra-level cluster of devices for system communication including:

providing a device logical identifier;

providing a data reference;

providing timing information; and

,

providing an IP multicast address.

9. The method of claim 1 wherein the first data frame comprises:

an A_PDU header;

a fault indicator for indicating the occurrence of a fault in the first one of the first intra-level cluster of devices;

an accelerator for determining the destination of the first data frame;

a data management field for indicating the type of data reference utilized in first data frame; and

,

a data value field.

10. The method of claim 1 wherein the first data frame is published to only a single subscriber device on the connectionless network.

11. The method of claim 1 wherein the first data frame is published via broadcasting to all of the first intra-level cluster of devices on the network.

12. The method of claim 1 wherein the step of providing a first inter-level cluster of devices includes providing a plurality of additional intelligent devices.

13. A method of communicating within a connectionless network having a plurality of devices comprising at least a publisher device and a subscriber device, the method comprising the steps of:

providing a first intra-level cluster of devices, the first intra-level cluster of devices including a first intelligent device and a first plurality of simple devices;

broadcasting a network clock signal throughout the connectionless network;

publishing a first data frame via user datagram protocol (UDP) and internet protocol (IP) by a first one of the first intra-level cluster of devices;

associating a first refreshment status with the published first data frame, the first refreshment status corresponding to the time of publication of the first data frame;

synchronizing the first refreshment status with the network clock signal;

subscribing to the first data frame wherein a second one of the first intra-level cluster of devices receives the published first data frame; and

,

associating a first promptness status with the published first data frame, the first promptness status being responsive to the second one of the first intra-level cluster of devices and corresponding to the time of receipt of the first data frame by the second one of the first intra-level cluster of devices wherein the second one of the first intra-level cluster of devices includes a timer capable of determining whether the duration of the published first data frame has exceeded a first predetermined time limit;

providing a first inter-level cluster of devices, the first inter-level cluster of devices including the first intelligent device and a second intelligent device;

publishing a second data frame via user datagram protocol (UDP) and internet protocol (IP), the second data frame being published by the first intelligent device;

associating a second refreshment status with the published second data frame, the second refreshment status corresponding to the time of publication of the second data frame;

subscribing to the second data frame, wherein the second intelligent device receives the second data frame; and

,

associating a second promptness status with the second data frame, the second promptness status being responsive to the second intelligent device and corresponding to the time of receipt of the published second data frame by the second intelligent device wherein the second intelligent device being capable of determining whether the duration of the published second data frame has exceeded a second predetermined time limit; and

,

providing a second intra-level cluster of devices, the second intra-level cluster of devices including the second intelligent device and a second plurality of simple devices.

14. The method of communicating of claim 13 further comprising:

entering a network fallback mode in response to the first refreshment status.

15. The method of communicating of claim 13 further comprising:

entering a network fallback mode in response to the first promptness status.

16. The method of communicating of claim 13 wherein the first predetermined time limit comprises:

a propagation delay associated with processing the first data frame throughout the connectionless network; and

,

a connectionless network delay.

17. The method of claim 13 further comprising sychronizing a local clock of the first one of the first intra-level cluster of devices with the network clock.

18. The method of claim 17 wherein the publishing of the first data frame being cyclical, the cyclical publication of the first data frame being responsive to the local clock of the first one of the first intra-level cluster of devices.

19. The method of claim 13 wherein the publishing of the first data frame being responsive to an event.

20. The method of claim 13 wherein the publishing of the first data frame being via IP multicasting to the first cluster of intra-level devices.

21. The method of claim 13 wherein the publishing of the first data frame being via broadcasting to all devices on the connectionless network.

22. The method of claim 13 wherein the step of providing a first inter-level cluster of devices includes providing a plurality of additional intelligent devices.