Mark Birks <m.birks@OMNIBUS.CO.UK> wrote:
> What I currently have is the following :
>         Single 9-pin D-type socket which can be configured as EITHER RS232
> OR RS422/485.
...
> Obviously this requires the card to be removed from the unit and chips
> inserted/removed as required.
>
> What I would *really* like is to have software config of the port or,
> perhaps, DIP switches on the front panel.

Sipex makes multimode serial transceivers which should be able to do
what you want:

        http://www.sipex.com/intrface.html#Multi

Cheers,
Eric