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Architecture Reset
Practical analysis of Open Process Automation and the O-PAS Standard for owner-operators, EPCs and integrators: how dependencies build up in control architectures, and how to write, test and buy your way out of them. By Trevor Cusworth.
All issues
O-PAS Factory Acceptance Testing: What Should an Open-System FAT Actually Include?
Traditional FAT proves functionality. An O-PAS FAT must also prove the open-system capabilities the owner purchased. Seven essential elements of an open-system FAT, who owns it, and what the owner should receive.
Read issue → Issue 08 · October 5, 2026O-PAS Interoperability: How Do You Prove a Multi-Vendor System Actually Works?
Conformance, interoperability and system integration answer different engineering questions. A six-part interoperability test for multi-vendor O-PAS projects, and how to measure it instead of declaring it.
Read issue → Issue 07 · September 28, 2026Application Portability in O-PAS: What Does “Portable” Actually Mean?
“Control applications shall be portable” survives the RFQ, the evaluation and the design review — until someone asks how FAT will prove it. A five-part portability test and how to write it into the procurement specification.
Read issue → Issue 06 · September 21, 2026Why EPCs Are Not Ready to Price O-PAS Projects
If an O-PAS RFQ landed on an EPC estimator’s desk tomorrow, could the team price it with confidence? A four-column test — scope, responsibility, evidence, cost — for every O-PAS requirement.
Read issue → Issue 05 · September 14, 2026What O-PAS Conformance Actually Changes for an Operator
“O-PAS conformant” takes one sentence to write into a specification. A four-question test for turning it into procurement decisions, integration responsibilities, FAT evidence and lifecycle expectations.
Read issue → Issue 04 · September 2, 2026Open IEC 61131 Is the Practical Future of Industrial Control
Moving to an open architecture should not mean throwing away the IEC 61131 programming model engineers already know. A portability test for finding where migration cost is building up.
Read issue → Issue 03The OPA Roadmap Does Not Start With Replacing the DCS
Where should an owner-operator begin with Open Process Automation? Not with a platform selection, but with a dependency map of the architecture they already run.
Read issue → Issue 02Why Incremental Modernisation Beats Another DCS Replacement Programme
When only the servers have reached end of life, why does the answer become a full DCS replacement? How separating applications, runtimes and infrastructure keeps routine lifecycle events routine.
Read issue → Issue 01Late Binding: The O-PAS Concept That Changes Modernisation Economics
Why committing early to runtimes, infrastructure and suppliers turns upgrades into migrations, and how late binding in O-PAS gives operators control over when hardware, software and suppliers change.
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