Define the boundary before collecting devices
Choose a plant, production line or clearly bounded service. Record what is inside the review and what depends on systems outside it. Include engineering workstations, controllers, human-machine interfaces, historians, network equipment and the interfaces used by suppliers. A device count alone does not explain how the operation works.
Begin with existing engineering drawings, maintenance records, configuration records and supplier documentation. Validate them with the people who operate the process. Treat discrepancies as work to resolve, rather than silently choosing whichever list looks newer. Discovery methods need an approved scope and an assessment of their operational impact.
A record that supports a decision
| Record | Question it answers | Evidence to retain |
|---|---|---|
| Process and location | What does this asset support? | Approved system drawing or process description |
| Owner and maintainer | Who can authorise a change? | Named role and escalation route |
| Model, firmware, software | Does a vendor advisory apply? | Verified version and collection date |
| Connections and dependencies | What happens if the link fails? | Source, destination, purpose and approved route |
| Recovery and maintenance | Can we safely make and reverse a change? | Restore procedure, test record and change window |
Separate known, inferred and unknown
Keep the source and last validation date beside each record. An inferred operating system is different from a version checked by an authorised engineer. An unknown dependency should be visible to the reviewer, not replaced with a confident guess. Restrict access to inventory details: they may expose sensitive architecture.
Make the inventory part of maintenance
Assign ownership for updates after equipment replacement, supplier access changes, firmware work and commissioning. Review a sample against physical and configuration records. A spreadsheet with a date is not proof that a recovery procedure works; keep the recovery test as separate evidence.
Worked review
Illustrative example: a line controller appears in the asset register, but the engineering laptop used to restore its project does not. Add the dependency, identify the role that maintains the project file and agree how restoration can be tested without affecting production. The useful outcome is a verified dependency and an assigned action, not a higher inventory completeness score.
Continue with the remote-access review and the local review workbook.
Sources & further reading
Continue the review
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