PLC FAT and SAT checklist: test behavior and handover evidence
Plan factory and site acceptance around requirements, observable results, failure states, approved changes and recoverable project files.
A useful acceptance test proves a requirement with an observable result. “Test PLC” is too broad to execute or review. “When the simulated tank level crosses the configured high threshold, the HMI displays the specified alarm with the correct identity and timestamp” gives the tester a trigger and an acceptance boundary.
Separate what the factory and site can prove
A factory acceptance test can exercise application logic, simulated I/O, HMI behavior, configuration and agreed interfaces before shipment. A site acceptance test checks the installed wiring, actual field devices, communications, services and behavior under the site's approved conditions. A simulated input at FAT does not prove the field loop is wired correctly at SAT.
Start with the FAT/SAT worksheet. For each test, record requirement ID, precondition, action, expected result, actual result, evidence reference, status and approval. Keep “not tested” distinct from “pass.”
Cover normal, abnormal and recovery behavior
| Area | Example observation | Evidence to retain |
|---|---|---|
| I/O | Correct device, channel, range and polarity | Approved loop-check record |
| Sequence | Transition requires the agreed conditions | Trend or sequence record |
| HMI | Units, state and command feedback agree | Screens and tag references |
| Communications | Loss and recovery are visible | Quality status and timestamps |
| Restart | Approved restart conditions are applied | Recovery test record |
| Handover | Project can be opened and restored | Versioned files and restore evidence |
Safety functions require their own competent validation and applicable procedures. A general PLC acceptance checklist does not establish a safety integrity or performance level. Coordinate any fault injection, power interruption or interlock test with the responsible site team and approved method.
Make defects reviewable
A failed test should identify the exact software and hardware revision, reproducible trigger and observed deviation. Record the defect, owner and retest result. After an application change, retest affected requirements and related transitions; do not erase the original failure record.
For example, changing analog scaling can affect display, alarms, trends and control calculations. A single correct HMI value does not close all those dependencies. The analog scaling guide gives a five-point check; the HMI alarm guide helps define useful operator behavior.
Finish with a recoverable handover
Deliver approved source projects, compiled/runtime versions where needed, device and network configurations, license dependencies, test results, known limitations and the restore procedure. Record who owns the next change. Test recovery on a suitable isolated target before calling a copied folder a backup.
The OT backup guide and restore-test worksheet extend this handover. The checklist here is a practical project template; contractual acceptance criteria and site procedures determine the required tests.
Cite this page: PLC FAT and SAT checklist: test behavior and handover evidence
, Shopfloor, 2026-10-11. https://shopfloor.space/articles/plc-fat-sat-commissioning-checklist/