Delayed publishing in process control systems
First Claim
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.
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Accused Products
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.
38 Citations
30 Claims
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1. A network device communicatively coupled to a process control system, comprising:
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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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method of delaying publication of data by a network device in a process control system, comprising:
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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. - View Dependent Claims (12, 13, 14, 15)
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16. A method of delaying publication of data by a network device in a process control system, comprising:
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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. - View Dependent Claims (17, 18, 19, 20)
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21. A method of delaying publication of data by a network device in a process control system, comprising:
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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 entry of a cache of the network device, the data to be published to the network and a timestamp corresponding to the data; when the network device is operating in the first mode, triggering a publication of the data corresponding to the process during the publishing timeslot, 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 during the publishing timeslot; and when the network device is operating in the second mode, triggering the publication of the data corresponding to the process, including; forgoing determining the oldest entry of the cache, forgoing publishing the contents of the oldest entry of the cache to the network, and determining a current value of the data corresponding to the process and publishing the current value of the data corresponding to the process to the network during the publishing timeslot. - View Dependent Claims (22, 23, 24, 25)
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26. A network device operating in a process control system, comprising:
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a processor; a cache; a network interface coupling the network device to a communications network included in the process control system; a process control interface configured to obtain values of a parameter corresponding to a process control function; a tangible, non-transitory memory having instructions stored thereon that are executable by the processor to; receive an indication of a publishing timeslot allocated to the network device; when the network device is operating in a first mode, during the publishing timeslot; obtain, via the process control interface, a current value of the parameter corresponding to the process control function, and publish, to the communications network via the network interface, the current value of the parameter; and when the network device is operating in a second mode, publish, during the publishing timeslot to the communications network via the network interface, contents of an oldest active entry stored in the cache, the contents of the oldest active entry including a previously obtained value of the parameter corresponding to the process control function, wherein the previously obtained value was obtained at an instance in time occurring prior to the publishing timeslot; and deactivate the oldest active entry after publishing the oldest active entry. - View Dependent Claims (27, 28, 29, 30)
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Specification