Opaque OPC UA NodeIds: why you don't type them by hand
An OPC UA NodeId isn't always ns=X;s=Name. Why browsing the namespace, UaExpert-style, remains the only reliable method against an opaque identifier.
OPC UA · CODESYS · UaExpert
From the field
Field notes
What we learn connecting real PLCs: protocols, addressing pitfalls, hardware choices.
Modbus registers: word, bit, real, and the Illegal Data Address error
A configured Modbus point that returns nothing, with no visible error. The cause is almost always the wrong table, or the word order of a float split across two registers.
Modbus · Protocols · Registers
Read-only PLC access: OT/IT segmentation explained
I don't want anyone touching my PLCs. What read-only access at the protocol level and OT/IT segmentation actually change — without an unearned certification claim.
Security · IEC 62443 · OT/IT