Are the protocol specs for Datalink available anywhere, or is it even public information at all?

I got this crazy idea that I should definitely be able to control my VDR box (see here) through the BM6500 using a Beolink 1000, and possibly vice versa... it should be possible to emulate a Datalink device using either the serial or parallel port and little interfacing.

http://www.beoworld.org/beotech/datalink.htm

The link at the bottom is broken but i think it is the file you're looking for. Someone here should have it...

Got it, thanks. It's clear enough on the physical layer and the data framing, but doesn't talk much on what the data frames actually contain.

Anyway, there's enough information for building a "spy" interface, and to start reverse engineering the messages. If I only had more free time... 

Ulf has built a VDR. See: www.ulf-kiener.de

You could also ask Ridax about that, he's the one who designed simple cables to control your Ipod or PC music through a datalink connection to the older BeoMasters/BeoCenters.