It appears that DwlWin doesn’t like using “USB to serial” converters (e.g. Prolific USB To Serial).
It downloads a file and then fails to establish comms with the target.
Is there anything that can be done other than making PCs with serial ports very precious?
Never had any problems with my USB-Serial converters…
What type (make/model) do you use?
I think the ones I’ve used with DWLWin have been FTDI, ATen, and a Digi “Edgeport”
But, if your download is starting, I think that means that the coms is OK - there is a fault in the target hardware somewhere;
eg, see: viewtopic.php?f=28&t=2235&p=15842&hilit=bootloader#p15842
The download succeeds when using a PC with a “real” serial port [you actually saw it happening 
]
Hiya,
I’ve had various sucesses and failures with USB-RS232 adapters.
Had 100% (so far!) sucess rate with the FTDI TTL-232-3V3 USB to TTL cables - see specs here.
Have had some issues with third party USB-RS232 adapters using the FTDI chips…don’t know why - although I have had more sucess with adapters with short USB cables than long USB cables…
ciao, Dave
I now have an Aten UC2322 - if you’ve used a similar port, what settings have you used?
Mine say, “UC-232A” (I have 2)- they must be over 5 years old now.
IIRC, DWLWin gives only one port setting, and that’s the speed - I would almost certainly have used 115200.
No I meant for the port driver. Normally I have to set “Tx FIFO” to 1 on serial port drivers, though there’s no such option for the Aten one, but instead there’s a whole page of settings that don’t mean very much. Time to get the 'scope out methinks