Re: DOSemu serial port problem

["Dr. Claudia Neumann" <dr.claudia.neumann@gmx.de>]

Hi Edenyard,

Am Freitag, 31. Oktober 2003 17:22 schrieben Sie:
>    Many thanks for your help, Claudia!
>
>    You suggested:
> > try:
> > $_com1 = "/dev/ttyS0"
> > no entries in $_ports and $irqpassing.
> > make sure you have right access to /var/lock or make a directory
> > /home/user/dosemu/lock and say in .dosemurc
> > $_ttylocks = "/home/user/dosemu/lock"
>
>    I tried that and I find that I can send data from my DOS programme
> out of the port and also receive data to my programme from the port,
> when I remove the $_ports and $irqpassing entries. I also no longer
> get any error messages. But...
>
>    Unfortunately, all is still not well: the programme has to drive
> the port's RTS line to control an RS232 to RS485 convertor (the
> equipment at the other end is RS485). The RTS line has to be made high
> whilst the PC is transmitting and then set low immediately after
> transmision so that the remote equipment can send its response.
>
>     Now I find with the settings that you suggest that, although the
> transmit and receive data is getting through, something other than my
> programme is controlling the RTS line. The result of this is that my
> programme cannot now transmit along the RS485 cable, because something
> is resetting RTS low after my programme has set it high but just
> before my programme's transmission starts.
>
>    I have checked and Xwindows is not trying to use the port (as far as
> I can tell) for a mouse. My mouse is on /dev/psaux. There is a modem on
> /dev/ttyS1 but, as far as Linux is concerned, /dev/ttys0 is unused.
>
>    Please could you suggest something that I can do to stop this.
> I don't understand why the system would let me transmit and receive
> using the port but at the same time interfere with just the RTS line....
> Do I need something to actually block the rest of the system from taking
> an interest in /dev/ttyS0, perhaps? What might be trying to use just the
> RTS line?

I am lost here. I don't know what a RTS line is. 

The only suggestion I can make is:
make a

find /etc -type f -exec grep -l /dev/ttyS0 { } \;

and you get a list of files which have an entry of /dev/ttyS0. Look at every 
file and find out if some other program uses /dev/ttyS0.

Or make the same with /var/log.

Hope that helps

cu

Claudia