This page introduces a white paper about how data and status changes are handled in asynchronous OPC UA workflows.
The main topic is synchronization after a write request or method call, when the expected result may appear later as:
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a status change
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a new value
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processed data becoming available
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a new queue entry
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confirmation that a configuration change has taken effect
The white paper explains why fixed deterministic delays are not a strong primary synchronization method, and why result-based synchronization is more reliable.
It also describes the two main techniques used in this context:
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polling for one-time workflow steps
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subscriptions for continuous monitoring
Small TOC
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Purpose
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Asynchronous workflow model
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Limits of deterministic delays
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Polling and subscriptions
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Design principles
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Conclusion
Download
White paper:
SPC_OPCUA_State_Synchronization_White_Paper.md