Process Control Network Device Delayed Data Publishing
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Solution Overview
Problem
Current network devices in process control systems are limited in their ability to publish data or events outside of allocated publishing timeslots, leading to loss of information between scheduled updates, which can result in an incomplete view of process control data and reduced system control effectiveness.
Innovation Solution
Implementing a network device with a cache to store process control data along with timestamps, allowing for delayed publication of this data during subsequent allocated publishing timeslots, thereby capturing and reporting all changes and events, not just those occurring during scheduled updates.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If network devices only publish data during allocated publishing timeslots, then network bandwidth usage is controlled and scheduling is simplified, but data completeness is reduced and information loss occurs between scheduled updates
Solution Approach 1:
The patent applies preliminary action by having network devices store data values in a local buffer before the allocated publishing timeslot occurs. Devices continuously sample and store process control data with timestamps in their buffers during intervals between publishing opportunities, so that when the publishing timeslot arrives, they can publish the most recent buffered value without waiting for real-time sampling to align with the schedule. This resolves the contradiction by ensuring data completeness (capturing all changes) while maintaining simple scheduled publishing.
2Loss of information
If network devices publish data at every allocated publishing timeslot, then data availability is improved, but network traffic increases and energy consumption rises
Solution Approach 1:
The patent applies partial action by having devices publish data selectively rather than at every publishing timeslot. Devices compare the buffered data value with the previously published value and only publish when a change is detected or when a minimum time interval has elapsed. This resolves the contradiction by maintaining data availability (publishing when relevant changes occur) while reducing energy consumption (avoiding unnecessary transmissions at every scheduled slot).
Solution Approach 2:
The patent applies feedback by implementing change detection mechanisms where devices monitor their own published data values and only trigger new publications when changes exceed a threshold or time interval. The system uses feedback from previous publication states to determine whether current buffered data warrants transmission, resolving the contradiction by balancing data availability with energy efficiency through intelligent publication decisions.
3Speed
If network devices wait for allocated publishing timeslots to publish data, then network scheduling is simplified and bandwidth is managed efficiently, but response time increases and system responsiveness deteriorates
Solution Approach 1:
The patent applies preliminary action by pre-buffering data values in device memory before publishing timeslots occur. Devices continuously sample and store process control data with timestamps during intervals between publishing opportunities, so when the allocated publishing timeslot arrives, they can immediately publish the most recent buffered value without waiting for real-time sampling to complete. This resolves the contradiction by improving publication speed (instant publishing at scheduled slots) while minimizing delay (data is already captured and ready).
Solution Approach 2:
The patent applies dynamics by allowing the publishing mechanism to adapt between two modes: scheduled publishing for normal operation and event-triggered publishing when critical changes occur. The system dynamically switches between waiting for allocated timeslots and immediate publishing based on the nature of the data change, resolving the contradiction by maintaining simple scheduling for routine data while enabling fast response for critical events.
Data Source
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AI summary
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.