[CentOS] syslog to serial term spits out garbage

SoNicX sonicx_ at gmx.net
Mon Aug 7 18:33:24 UTC 2006


thanks for the great info. i just solded (?)
2-3
3-2
5-5
G-G
and it works now even on 115kbps, as there are some lines left iin the cabel 
ill try that 
4
6 20
8
to, for some more luxus. rs232ports are such a nice feature. my server board 
supports remote access so its even nicer. but i still have to switch speeds 
that way, i guess minicom will eat some script to change speed to 115k after 
boot. thanks again.
sonicx

On Monday 07 August 2006 20:13, William L. Maltby wrote:
> On Mon, 2006-08-07 at 19:34 +0200, SoNicX wrote:
> > hello,
> > i have wired myself a nullmodemcable to connect a small machine to my
> > centos-ltsp-and-so-on-server.
>
> Garbage null-modem cables can cause problems, A reliable one has
> something like
>
>          2      3
>          3      2
>
>          4
>          6      20
>          8
>
>                  4
>         20       6
>                  8
>
> 468 jumped together and go to 20 on the far side. This is a
> "symmetrical" null modem cable and allows for hardware flow control and
> detect power on, etc. I seem to remember 5 being int there somewhere, so
> google and make a good null-modem.
>
> The other part you need to do is mentioned below.
>
> > using agetty i can login fine, just a few
> > garbage chars here and there but working is ok. now this isnt what i
> > wanted, so i disabled agetty, made a line in syslog.conf like
> > *.* /dev/ttyS0
> > and made the system produce a lockfile after syslog is started to lock
> > that serial port. now data reaches my minicom using terminal emulator,
> > but its garbage, looking like this:
> > ...x.x.x at ..x.x.
> > and so on. if i do
> > echo "somechar" > /dev/ttyS0
> > its the same garbage. im sure this is a quite simple thing, but i dont
> > get it to work. do i need another terminal prog if i try to send
> > plaintext with syslog (as it seems to me clueless as i am). do i need to
> > manipulate syslog output somehow? i tried to fiddle around with setserial
> > but the port should work, as they to with agetty. i hope someone on this
> > list has experience with this, doenst seem to be too popular.
>
> 'man stty' might help too. The problem is you need to maintain a
> consistent baud rate. Once the terminal line is opened and *held* open,
> your baud rate, parity, line discipline, etc should remain. When line is
> closed, it falls to some default, but can float.
>
> Keep in mind that RS-232-C (?) specs ap[ply and there are limits as to
> distance (un-amplified) and baud rate. I presume you are not trying for
> 2400?
>
> Anyway, get the line open and run the stty against it and let the
> process that opened it sleep forever with the line open.
>
> > mfg
> > sonicx
> > <snip sig stuff>
>
> HTH



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