Hi.
I would like to include support for signalling via the parallel port (and its five input pins), as used by various other automation system.
Does anyone own such an interface and can assist me in testing my code? I don’t have the needed resistors here, and I want to blow up mainboard 
Torben
The outputs are logic high/low (5v+0v) levels - which you can measure with a simple volt/multi-meter. Inputs are closing contacts to ground. I’ve never really done much with that port (preferring the game port) 
There’s a prospective customer who would like to reuse his existing interface originally built for a different automation software. I personally prefer other methods (USB gamepad, IO-Warrior) as well.
So I can just short-out the input pins with GND? No resistor or something?
Look on this link.
http://www.avt-nbg.de/download/documentation/000118_V01_o.pdf (german)
There are some examples that can help you. Beginning on Side 65.
We use this Interace to Remote-Controll our Studio during an Outdoor-Session via ISDN. It also can be used to controll an lokal PC.
Hope i could help a little bit 
Greetz
Polli
Wenn Sie diese Schaltung nicht verwenden, muß der entsprechende Anschluß über den Schalter auf Masse gelegt werden. Dabei ist die invertierte Schaltwirkung zu beachten.
“[…] you can simply connect the pin to GND […]”
Thanks 