simple serial loopback

[Loren M. Lang]

On Thu, Jan 27, 2005 at 10:00:40AM +0100, Florian Hengstberger wrote:
> Hi list!
> I'm currently trying to setup my box for simple data transfer
> to a microcontroller via the serial interface.
> Therefore I've wired a nullmodem cable and as a first test
> I was trying to connect from cuaa0 to cuaa1 simply by

Generally you shouldn't need a null modem for a microcontroller, just a
regular cable.  That's because it's expected to be a slave to a PC, I
think the technical term is "Data Set," which is just like a regular modem
is a "Data Set," where a PC is a master or "Data Terminal."  So PC to PC
you need a null modem since it's "Data Terminal" to "Data Terminal."

For monitoring my tty I find minicom or "cu -l /dev/cuaa0" to work just
fine.

> 
> xterm1: cat /dev/cuaa0
> 
> xterm2: echo "Something" > /dev/cuaa1
> 
> Unfortunatly cat exits with 0 after the first echo although it
> displays the message correct,
> so I have to "cat /dev/cuaa0" everytime I send something.
> Why is this?
> 
> Is there a better way to keep track of the ascii-chars sent
> over a serial connection?
> Kermit and minicom seem to be some sort of monster for
> real serial connection (initialisation ...) which is a bit to much
> for me.
> In the end I just wan't to see the chars sent over the cabel
> and wan't to reply to them by typing on the keyboard, that's it!
> 
> Thanks in advance
> Florian
> 
> PS: Maybe a simple shell/perl script can help, should I focus on that?
> 
> 
> ------------------------------------------------------
> Linux/BSD: The daemons are not longer just in my head!
> ------------------------------------------------------
> Florian Hengstberger
> e0025265 at student.tuwien.ac.at
> http://stud3.tuwien.ac.at/~e0025265
> ------------------------------------------------------
> 
> 
> 
> 
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