IO-redirection seems to be not working

[matthschulz <matthschulz@gmx.net>]

I'm trying to setup a connection of an multimeter to ttyS0. It gives a steady
stream of lines to the port. (CONRAD VC96 for whom who knows)

When I use minicom for this, it works fine. The input is written on the sceen,
can be saved and so on. I can leave minicom with ^A^Q and then cat /dev/ttyS0
writes the lines to the screen.

But I have planned to program some functions to this stream at least maximum,
minimum, average and others. 

So I tried to do the following in order to get rid of minicom:

>stty -F /dev/ttyS0 -parenb cs8 cstopb cread ixon isig ispeed 1200

to set the required 1200,8,N,2. No luck, >stty -F /dev/ttyS0 shows the change,
but the port is not setted to 1200 bps.

While I was playing with stty and setserial, I figured out, that the command 

>stty -F /dev/ttyS0 -echo

the echo on my actual ttyp0 changes, not this at /dev/ttyS0 !
Either ">stty -F /dev/ttyS0 echo"    or  ">stty echo" bring the echo back.

Space between -F and /dev... doesn't matter.
ttyp0 or tty doesn't matter.
X (KDE) running or not doesn't matter.
BASH_VERSION='2.01.1(1)-release'


Any ideas?

Matth