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Re: cua/tty problems



Quoting Christian Schroeder (csc_(_at_)_schrettnix_(_dot_)_org):
> On Thu, Jul 10, 2003 at 10:33:11PM -0700, Dan Shechter wrote:
> Hi,
> 
> > I tried to connect to a cisco router with: 'cu -l /dev/cua00 -s 9600'
> > and got the answer : connected. but nothing happens.
> 
> cu -l /dev/tty00
> 
> It's BSD not Linux.

cu and tty have been with us since before Linus wrote his name
in double digits.  That's background.

tty's are traditionally there for INPUT devices like, terminals
and, er, ttys. 

cuxx devices (however they get numbered) are traditionally
used as "Calling Unit" devices - another way to address
the same port, but it handles locking in a different way.

We use "cu" for modems (they can call in and dial out).
We use tty for our terminals (yes, I have a vt420 and a wyse
50 floating around), we use tty for serial printers, plotters -
things that are entirely one way (out).

You're looking at potential hardware handshaking and, most likely,
null modem issues. (is pin 2 on one end attached to pin 3 on other).

When I have serial problems like this I do two things:

1) I stick my little $9 '232 debugger' box on it.  It's got
   LEDs that light up/turn the right color depending.

   Look at it.  Connect.  Did it change?

2) I also use slightly smarter (or just different) connect commands.
  Minicom is a fullblown tool taht lets you change speed, etc on the fly.
  Kermit is the old brother or great uncle, depending (I use an older
  modem for fax that happens to speak kermit in its hardware.  Much
  faster than its competition, it still maxes out at 19.2).

  From habit, I use tip to connect.

But yeah, hit return a couple times.  Look at the cable.  90% of problems
involve the wires.



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