Delayed publishing in process control systems

Patent metadata

Field	Value
Publication number	US-9002973-B2
Application number	US-201213653489-A
Country	US
Kind code	B2
Filing date	Oct 17, 2012
Priority date	Oct 21, 2011
Publication date	Apr 7, 2015
Grant date	Apr 7, 2015

Abstract

Techniques for delaying the publication of data to a network by a device in a process control system or plant include obtaining, at the device, data to be published to the network; storing the obtained data and a corresponding timestamp in a cache; triggering a publication of cached data; and, based on the trigger, publishing the oldest cached data to the network during the publishing timeslot assigned to the device. The cached data may correspond to a sample rate of the device and may include multiple instances of data obtained over time. The device includes a network interface, a cache, and a publisher, and the device may be configured to operate in the delayed publishing mode, or to operate in an immediate publishing mode in which currently obtained data that has not been cached is published to the network during the publishing time slot assigned to the device.

First claim

What is claimed:

1. A network device communicatively coupled to a process control system, comprising:
a connection to a network included in the process control system;
a publisher configured to publish data to the network of the process control system during a publishing timeslot allocated to the network device, wherein the data corresponds to a process controlled in the process control system, the data is obtained in accordance with a sample rate corresponding to the network device, and a rate of re-occurrence of the publishing timeslot is less than the sample rate corresponding to the network device; and
a cache storing one or more entries, each entry of the one or more entries including a value of the data corresponding to the process and a respective timestamp,
wherein the publisher is triggered to publish, to the network via the connection and during the publishing timeslot, contents of a particular entry of the cache that includes a particular timestamp corresponding to an instance in time that occurred prior to the publishing timeslot.

2. The network device of claim 1 , wherein the one or more entries of the cache correspond to the sample rate of the network device.

3. The network device of claim 2 , wherein the sample rate is configurable.

4. The network device of claim 1 , wherein the publishing timeslot is included in a plurality of publishing timeslots allocated to the network device, and wherein at least one entry of the cache includes a respective timestamp indicating an instance in time that occurred after an occurrence of a first publishing timeslot and before an occurrence of a second publishing timeslot immediately subsequent to the first publishing timeslot.

5. The network device of claim 1 , wherein the network supports a HART protocol.

6. The network device of claim 5 , wherein the HART protocol is a wireless HART protocol.

7. The network device of claim 1 , wherein the data corresponding to the process corresponds to a process control event.

8. The network device of claim 7 , wherein the process control event corresponds to a particular state, the particular state included in a set of two or more states.

9. The network device of claim 1 , wherein the publishing timeslot allocated to the network device is indicated by a network manager coupled to the network, and wherein the publisher is triggered to publish the contents of the particular entry to the network manager via the network.

10. The network device of claim 1 , wherein:
the entry stored in the cache is an oldest active entry stored in the cache,
the oldest active entry is determined based on the respective timestamp included in the oldest active entry, and
the oldest active entry is deactivated after publishing.

11. A method of delaying publication of data by a network device in a process control system, comprising:
receiving, at the network device coupled to a network included in the process control system, an indication of a publishing timeslot assigned to the network device;
independent of an occurrence of the publishing timeslot, obtaining, at the network device, data to be published to the network in accordance with a sample rate corresponding to the network device, the data corresponding to a process being controlled in the process control system, and a rate of re-occurrence of the publishing timeslot being less than the sample rate corresponding to the network device;
storing, in an entry of a cache of the network device, the data to be published to the network and a timestamp corresponding to the data;
triggering a publication of the data corresponding to the process, including determining an oldest entry of the cache; and
publishing, by the network device, contents of the oldest entry of the cache to the network.

12. The method of claim 11 , wherein obtaining the data corresponding to the process comprises at least one of: obtaining data corresponding to an event associated with the process, or obtaining a value of a parameter associated with the process.

13. The method of claim 11 , wherein the network is a wireless HART network, and wherein publishing the contents of the oldest entry of the cache to the network comprises transmitting, using a wireless HART protocol, the contents of the oldest entry of the cache to a network manager coupled to the network.

14. The method of claim 11 , wherein:
triggering the publication of the data corresponding to the process comprises triggering the publication of the data corresponding to the process during the publishing timeslot, and
publishing, by the network device, the contents of the oldest entry of the cache to the network comprises publishing, by the network device, the contents of the oldest entry of the cache to the network during the publishing timeslot.

15. The method of claim 11 , further comprising configuring the sample rate corresponding to the network device.

16. A method of delaying publication of data by a network device in a process control system, comprising:
receiving, at the network device coupled to a network included in the process control system, an indication of a publishing timeslot assigned to the network device;
independent of an occurrence of the publishing timeslot, obtaining, at the network device, multiple values over time of data to be published to the network in accordance with a sample rate corresponding to the network device, the data to be published to the network corresponding to a process being controlled in the process control system;
storing, in a different entry of a cache, each value of the multiple values of the data and a timestamp corresponding to the each value;
triggering a publication of the data corresponding to the process, including determining an oldest entry of the cache; and
publishing, by the network device, contents of the oldest entry of the cache to the network.

17. The method of claim 16 , further comprising configuring the sample rate corresponding to the network device.

18. The method of claim 16 , wherein obtaining the data corresponding to the process comprises at least one of: obtaining data corresponding to an event associated with the process, or obtaining a value of a parameter associated with the process.

19. The method of claim 16 , wherein the network is a wireless HART network, and wherein publishing the contents of the oldest entry of the cache to the network comprises transmitting, using a wireless HART protocol, the contents of the oldest entry of the cache to a network manager coupled to the network.

20. The method of claim 16 ,
triggering the publication of the data corresponding to the process comprises triggering the publication of the data corresponding to the process during the publishing timeslot, and
publishing, by the network device, the contents of the oldest entry of the cache to the network comprises publishing, by the network device, the contents of the oldest entry of the cache to the network during the publishing timeslot.

21. A method of delaying publication of data by a network device in a process control system, comprising:
receiving, at the network device coupled to a network included in the process control system and operable in a first mode and a second mode, an indication of a publishing timeslot assigned to the network device;
independent of an occurrence of the publishing timeslot, obtaining, at the network device, data to be published to the network, the data corresponding to a process being controlled in the process control system;
storing, in an en

Assignees

• Fisher Controls Int

Inventors

• Panther Mitchell Stephen

Classifications

• H04L67/12 Primary

  specially adapted for proprietary or special-purpose networking environments, e.g. medical networks, sensor networks, networks in vehicles or remote metering networks · CPC title

• H04L67/325 Primary

  Electricity · mapped topic

• H04L67/2842

  Electricity · mapped topic

• H04L67/568

  Storing data temporarily at an intermediate stage, e.g. caching · CPC title

• H04L67/62 Primary

  Establishing a time schedule for servicing the requests · CPC title