Compiling Clean Isn't Proof: Have AI Review a PLC Program Before You Commission It

Description and use

AI‑driven review of TIA Portal PLC programs uncovers hidden logic defects that compilers miss, producing a read‑only report with confirmed issues and fix suggestions.

Problem

Inherit a TIA Portal PLC program that compiles with no errors or warnings but may contain logic defects that can cause unsafe or incorrect operation.

Outcome

The AI review identified 2 P1 defects (wrong chain logic and conveyor run), 2 P2 defects (short actuator pulse and compiler warning), 1 P3 defect (missing safety logic), and eliminated one false positive through counter‑evidence.

Workflow

• Define a 7‑category checklist (structure, state, timing, interlocks, data, maintainability, testability).
• Provide the checklist and a brief to an AI agent via TiaLink MCP gateway.
• AI reviews the program read‑only, producing findings that include evidence, failure scenario, severity, confidence, fix suggestion, verification method, and counter‑evidence.
• AI outputs a report with a global writers table and a read‑only declaration.
• Human reviewers verify each finding and apply fixes in a separate change process.

Evidence

The compiler checks syntax and consistency — not cross‑network logic bugs like "the infeed conveyor runs when no box is present."

Source

Every candidate finding must carry seven elements: evidence, the failure scenario, a severity grade, confidence, a minimal‑change fix suggestion, a verification method, and a counter‑evidence pass.

Source

Per the lesson's own published results (I have not independently re‑run them; treat the numbers as the course's): 2 × P1, 2 × P2, 1 × P3, 1 false positive eliminated by counter‑evidence.

Source