PLC / Backups, Changes & Commissioning
Investigate a PLC running old logic after a power interruption
Some platforms distinguish the currently running application from the stored boot application used at restart.
Environment and inputs: Industrial PLC / automation guidance · Verify the exact controller, module, firmware, engineering tool and machine documentation. Linked vendor examples apply to their stated products and library versions; observation, state changes and physical work require distinct authorization.
Observe and record
Compare approved application identifiers, deployment records and the target's documented boot-storage behavior without cycling power as a test.
Interpret the evidence
An online change or download does not universally update every boot image. Exact persistence and startup rules depend on the target and tool settings.
Resolve and verify
Have the controls owner reconcile the supported boot application with the validated running revision, then verify through an authorized isolated or scheduled recovery test.
Machine and data safeguards
Do not power-cycle a live machine or overwrite boot storage before confirming the intended source and data recovery plan.