Large language models are excellent at language and weak at being treated as a control authority. In OT, that distinction is non-negotiable.
The right role
Use an LLM to summarize alarms, explain PLC logic, search procedures, draft SQL and help engineers navigate documentation.
The wrong role
Do not let a model silently bypass safety logic, change a setpoint or issue an uncontrolled production command.
A safer architecture
Use Read → Reason → Verify → Act. The model proposes; a deterministic layer validates; an authorized person or controlled system performs the action.
Why this matters
OT software operates physical equipment. A plausible but wrong answer can become a stopped line, a quality deviation or a safety event.
Final takeaway
The engineering value comes from a measurable improvement, explicit boundaries and a design that remains understandable when the system is under pressure.