I bought this a while back and tried to use with an RNS-315. The RNS-315 as I figured out is not designed to interface with a vw tv tuner which this unit emulates. I hacked the wire harness up a bit but I did solder all wires back. I never hooked this to an rns-510 so I am not sure how it works. The last owner had it working so I don't see why it won't. It is used to bring composite audio and video ( from iPod, video games etc) into unit under the tv input. iPods will need apple composite video cables sold separately .This is the link to the units manufactures web site. http://www.t-era.co.uk/Pub/default.a...E_10&ID=201538
The unit also has a RVC camera input . The harness has a 4 pin connection for the RVC Camera input but one of the wires was pulled out . I guess if you want to use this for RVC camera you can either email Manufacture and buy a new harness or try to fix this one by soldering a new wire to the missing pin connection. This cost about $250 new with the pound to dollar conversion. I will sell for $60 shipped in lower 48 bout unit is as is. It does come with directions for hookup and info for VCDS ( vagcom ) coding . The can gateway must be programmed to look for TV tuner. This also plugs into the 26 pin audio video connection on back of rns-510 . If you have an OEM Camera hooked up this has to use the same connection so you would not be able to use both. Here are a few pics of unit.
Where are you located? The 4 pin connecter for the RCV, is that for oem or for aftermarket. If I read your description correctly, I'd assume that the broken 4pin in is for aftermarket camera, and that oem camera is not possible when using this unit. Is that right?
Also, how does one switch from composite input to the actual RNS interface and vice versa? Is there a button on the unit, or is there a software button on the screen that allows me to switch to the Composite input. Do you know if the touch screen still works when in TV mode? Do I use the touch screen to get back to the RNS interface?