I tried to send you a email but it was returned.
Cable must be correct.
Handshake is done at the PC.
8 data bits, 2 stop bits, no parity, X on X off enabled.
Program starts with a :1234 (example) and ends with a M30.
The % sign is for a tape reader.
I used DOS version of PROCOMM through Port A to upload download and edit. Prior to that I used a TRS80 Model 100 (23 years ago).
Do you have the manuals?
George
(Note: The opinions expressed in this post are my own and are not necessarily those of CNCzone and its management)