Field notes

Notes from the bench

Things that went wrong on real hardware and what they turned out to be. Mostly embedded Linux, industrial protocols and the gap between a datasheet and a board that actually boots.

What a register map doesn't say

One word in a config file decides whether a kWh total reaches a SCADA master as a counter or as a measurement. Nothing in the vendor's spreadsheet tells you which. Notes from writing the thing that guesses — including the bug that would have made every reading on a customer's HMI ten times wrong.

8 October 2026 · Modbus, DNP3, BACnet, IEC 61850

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Notes from the bench

What a register map doesn't say