Re: [hylafax-users] Serial latency

["Jay R. Ashworth" <jra@baylink.com>]

On Fri, Jun 29, 2001 at 09:31:45AM +0100, Tim Allen wrote:
> > > Breakout box shows no activity on pin 20 during transmission,
> > > pulses on hangup. So it looks as if our hardware handshaking from
> > > the Linux end isn't working. Presumably this is all done by kernel
> > > routines called by Hylafax which should toggle the DTR line when
> > > the UART fifo is getting full. Tried XonXoff for good measure with
> > > no improvement, so that may help to pinpoint the level at which
> > > things aren't working.
> >
> > Hmmm... you should actually be looking at pins 4 and 5, and
> > specifically, if I'm reading this chart correctly, pin 4, Request to
> > Send, which my chart says is a signal Inbound to the DCE (modem).
> >
> > That's the one that should toggle if the modem tries to overrun the
> > serial port.
> >
> > Check setserial to see if the port is in hardware handshake mode,
> > too, I think. [ looks ] Nope. stty. The flag is rtscts. Do an
> >
> > stty </dev/name
> >
> > *while* faxgetty has the modem, and see if that's set. If not, then
> > faxgetty is blowing it for some reason.
>
> RTS is stuck too. stty reports clocal crtscts -ixon -ixoff which looks
> right to me. Switched to xonxoff mode and it reports clocal -crtscts
> ixon ixoff which also looks ok, but still losing data so it looks like
> neither handshaking mode is functioning correctly at the DTE end.

Hmmm...

I think clocal is broke, actually.  My stty manpage says that clocal
means "disable modem control signals".  I think it actually means CD
and DTR, but in any event, it doesn't seem to bode well here, and I'm
not sure why it might be wrong.

But you're right; if the lights aren't blinking that sounds like the
computer end.  Got another serial port, or card?

Cheers,
-- jra
-- 
Jay R. Ashworth                                                jra@baylink.com
Member of the Technical Staff     Baylink
The Suncoast Freenet         The Things I Think
Tampa Bay, Florida        http://baylink.pitas.com             +1 727 804 5015

   OS X: Because making Unix user-friendly was easier than debugging Windows


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