Re: Problems w/ serial flow control

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On Wed, 2006-05-31 at 12:14 -0600, Philip Prindeville wrote:
> Tim wrote:
> > On Tue, 2006-05-30 at 21:25 -0600, Philip Prindeville wrote:
> >   
> >> I'm running FC3 on an MSI-7142 (K8MM-V motherboard), and using
> >> the two serial ports on the m/b.  I used the stock
> >> out-of-the-shrinkwrap settings for most hardware (except for the sound
> >> board and X drivers), and things have worked fine.
> >>
> >> But... when connecting to a router's console at 115200 with either
> >> RTS/CTS or XON/XOFF flow control, I'm seeing dropped characters.
> >>     
> >
> > Looking at a friend's router, his one's serial port connection *ONLY*
> > had the three-wire type of serial connection.  So his couldn't possibly
> > use hardware handshaking (RTS/CTS).  Perhaps yours can't too?
> >
> > Also, check what your router says about its maximum port speeds and
> > handshaking protocols.
> >
> >   
> 
> It is an 8-wire connection (over RJ-45 to DB-9), and can do 115200 (max 
> rate)
> with either XON/XOFF or RTS/CTS.
> 
> I've tried both, and they're both lossy.
> 
> The issue is on the PC as the receiver...

Remember that both ends have to agree on the flow control.  If one is
running  RTS/CTS and the other is XON/XOFF, you don't have flow control.
At 115K, I'd always opt for RTS/CTS...XON/XOFF requires CPU intervention
unless you have fairly sophisticated hardware.  All you have to do is
be a bit pokey at responding to an interrupt and you'll drop characters.
RTS/CTS is usually done at the hardware level and is a bit more
reliable.

----------------------------------------------------------------------
- Rick Stevens, Senior Systems Engineer     rstevens@xxxxxxxxxxxxxxx -
- VitalStream, Inc.                       http://www.vitalstream.com -
-                                                                    -
-           Blech!  ACKth!  Ooop!  -- Bill the Cat (Outland)         -
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