Hi, just for info..
I'm using the new Graupner Model MX 12 with DSC Plug.
Bought a seriell PIC Interface from ebay.de with 3,5mm Stereo-Plug.
First I can't get signals, only for a few Seconds, when plugging the connector in, or hold the connector half-plugged.
After I changed the assignment of the plug, I get fine signal, even with fully-plugged connector
+---------------+----+---------------
===| signal (brown) | --- | ground (white) >
+---------------+----+---------------
If I change the two cables, the signal fades away in a few seconds. have fun