is there any way to find out what's *sometimes* going wrong with my serial communication?
I use CoolTerm to send HPGL Plotfiles (Simple ASCII-Files) to a HP DraftPro EXL Pen-Plotter from 1988 through a USB to Serial Adapter with a Prolific Chip and the relatively new PL2303 Driver from Prolific, using hardware handshake (CTS), since Xon/Xoff seemed unrelieable. In general, this works well. The files are typically below 5MB, and they take between one and up to 5 hours to be drawn; since there is practically no buffer, they must be sent *very* slow. Normally CoolTerm shows the CTS/DSR lights shortly flashing every 2 seconds or so and sends the next packet, etc.
While it works most of the time, every few hours a fatal communication failure of some sort occurs:
- - the plotter stops working (and never starts again)
- CoolTerm shows CTS=on, so it continues to send until EOF
These glitches seem to happen at pretty random intervals, unrelated to the actual data that is being sent.
If I was able to find at what point during the transmission the errors occur, I could at least try to pick up resending the file at the right position (it would not have to be exact, since it's ok to plot some lines twice).
So my question would be: is there a way to make CoolTerm protocol the transmission and the CTS signals received?