Hi Gunnar,

You only have 3 outputs in your 9-pin port - TX data, RTS, and DTR. The TX pin is only 'active' while sending data, otherwise in is in the 'mark' (-) state. These are purely hardware functions, so you are somewhat limited in what you can do, regardless of method of software control. If you need more control or more devices look at RS-485 which you can drive from your pc - http://www.bb-elec.com/tech_articles/rs485_basics.asp for starters. Have fun!