[Soekris] BIOS setting to completely ignore COM1 ?

Anton Roeckseisen anton_roeckseisen at genua.de
Mon Jul 4 07:51:31 UTC 2005


Hi,

On Sun, Jul 03, 2005 at 06:58:50AM -0700, Dirk-Willem van Gulik wrote:
> 
> Is there a BIOS setting to completely ignore COM1 for the NET4501 and the
> NET4521 ?
> 
> The issue which I am having is that I have a PLC connected to COM1 which
> happens to regularly output the ctrl-P hex code. This causes the soekris
> not to reliably reboot after a powerfailure.
> 
> Any hints.

PLC? Some kind of custom electrical circuit I suppose...

Some time ago I did a prove of concept to operate a dial-in modem on
the soekris 4501. It contained an electrical circuit that controlled the
DTR line of the modem in a way I could enable DTR via the builtin 
GPIO-Ports. So no one could access the BIOS via a dial-in session.
Maybe you could do something similar.

Another idea is to use another baud rate for the custom conversation 
with the PLC. This decreases the probability that valid ctrl-P hex code
characters get detected - but is rather a hack....

Bye,
	Anton





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