I have a PIC feeding either a XP PRO SP2 or ME 2nd edition at 9600 Baud 
over RS-232. The ME running Telix (an old DOS program), the stuff 
scrolls very quicky. Using Telix on the XP the scrolling is much slower. 
Using REALTERM  on the XP there is no indication of overflow, but 
scrolling is similar to Telix on the same machine. Don't have a good 
explanation, but do know 9600 will scroll fast if allowed. I don't use 
Hyper term. I don't use hardware or Xon/Xoff flow control. Wish Gary 
Kildall ethics had prevailed and we would had solid O/S for IBM. Have 
you tried adding some delays to slow down the PIC? My application is 
watching 2 pressures and one temperature, and pushing it out a fiber 
optic link to RS-485 to a PLC, the readings don't change that quick, 
where once a minute is fine, so speed isn't an issue. The 9600 is 
default for the PLC.

Shawn Wilton wrote:
> I'm having issues communicating with an XP PC over RS232.
>
> I know my code is good because I can communicate via serial using one of
> those USB-UART chips.  But when I hook this PICDEM+ to the PC via a genuine
> RS232 serial port, I constantly get an overrun error.  I looked at the data
> in the debugger and I'm getting "."(0xC3) constantly.  Apparently faster
> than the uC can handle the packets.
>
> Any ideas where the data is coming from?  There's nothing running on that
> serial port in terms of s/w.  Perhaps someone else has seen this or has an
> idea what's going on?
>
>   
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