Re: DOSemu serial port problem

["Edenyard" <mail@edenyard.co.uk>]

   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?

   Thanks again for your help!

   Cheers,

      Gerald.