GxP change control for PLC without the audit-week scramble
Approval, deployment and audit of every PLC, SCADA and HMI change — aligned to GxP / 21 CFR Part 11 from day one, generated as a by-product of the work, not assembled the week before the audit.
What counts as an OT change
PLC code
Logic edits, routine changes, function-block swaps, firmware updates.
SCADA tags
Point database additions, alarm threshold edits, scaling changes.
HMI graphics
Screen layout, button bindings, operator permission scopes.
Recipes
Production recipes, setpoints, batch parameters, ingredient lists.
Machine parameters
Drive parameters, IO config, safety thresholds, network topology.
How VEM aligns to GxP / 21 CFR Part 11
21 CFR Part 11 requires electronic records to be attributable, legible, contemporaneous, original and accurate — and electronic signatures to be unique to the signer and inseparable from the record. VEM applies cryptographic signatures to every captured controller state, binds the signature to an authenticated user, and locks the audit trail against retroactive edit. EU Annex 11 expectations on validated change control, risk-based review and full traceability map directly onto the same workflow. See the broader the complete OT change management guide for the cross-regime crosswalk.
A sterile-fill manufacturer running 11 packaging lines uses VEM as the system of record for every PLC and HMI change in the GMP boundary. When an FDA inspector pulled a 12-month sample of recipe changes during a routine inspection, every sampled change produced an electronically signed record with the requester, approver, diff and deployment timestamp on a single PDF.
Request → Review → Deploy → Audit
Request
Engineer files a change with the proposed diff attached.
Review
CAB or single approver reviews the diff, risk and deployment plan.
Deploy
VEM pushes the approved version, captures before/after signatures.
Audit
Immutable record links request, approval, diff and deployment.
Other regimes covered
Want the full framework? the complete OT change management guide.