| CPC G06F 21/125 (2013.01) [G05B 19/058 (2013.01); G06F 21/64 (2013.01)] | 18 Claims |

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1. A method of performing secure write operations comprising:
receiving a secure write instruction at a programmable-logic controller (PLC);
performing a validation operation on the secure write instruction at the PLC;
rejecting the secure write instruction responsive to determining the secure write instruction is invalid; and
responsive to determining the secure write instruction is valid:
verifying a permissibility of the secure write instruction at the PLC by comparing one or more parameters of the secure write instruction to a range of permitted values stored in the PLC;
rejecting the secure write instruction responsive to determining the secure write instruction is impermissible; and
executing the secure write instruction at the PLC responsive to determining the secure write instruction is permissible.
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