FDE Times: in OT, AI may recommend but must never command the PLC

On a plant floor, operations teams care less about model cleverness than whether your system can write to a PLC. FDE Times published a practical guide on 12 October 2026 that turns late-2025 joint guidance from CISA, Australia’s ASD ACSC and partners into three rules FDEs can take into an OT customer: data may flow out, but commands may not flow in; humans keep decisions that affect the physical world; and there must always be a documented way to switch the AI off and fall back to manual or fixed-rule control.

The piece maps those rules onto ISA/IEC 62443 vocabulary—zones, conduits, and security levels as a vector across seven foundational requirements (target, capability and achieved)—and walks through a pumping-station energy agent that only proposes schedule changes an operator then enters through the HMI. It also flags common mistakes: treating “read-only” as an account permission on a two-way link, turning approvers into reflexive button-pressers, and claiming “SL2” as if a security level were a single number.

For FDEs, the career tip is concrete: when a job post mentions IEC 62443, NIST SP 800-82 or OT/ICS, bring a zone-and-conduit diagram and a one-page failure-state sheet to the interview, and describe designs that keep AI recommendations out of the control path.