From elsewhere
Going slightly off topic but since Peter introduced the subject of ADS-B, the Garmin GTX345 transponder has a feature where it takes in the signal from the TAS600 and sends out a composite ADS-B + TAS traffic information, managing double targets properly (or so I’m told).
There is more than one such “traffic data merging” option. I recall some past threads – here here here.
One outstanding Q is whether you still get audio warnings on traffic data merged after the TAS box… the traffic warnings normally come from the TAS box. So if you merge the ex-TAS6xx data with ADS-B-IN data coming from some other box, the TAS6xx audio will not be generated on the latter traffic.
We have a huge number of “ADS-B” threads but it’s quite possible that nobody has actually installed any of this 
Chris Parker has done it I think? And I’m getting it in two weeks.
From the GTX345 manual:
The GTX 345 provides all traffic aural alerts.
I did ask Chris but he didn’t comment so maybe he has something else. In this case it sounds like you rewire the intercom to get the traffic audio from the GTX345 instead of the TAS6xx.
Unfortunately it doesn’t do the same trick for weather, it could have been a nice way to get Avydine or Gloze weather on the Garmin panel avionics :-)
Certified avionics generally cannot display data from uncertified sources, but sometimes there is a way e.g. via NTSC video. Or you could do it (illegally) with a protocol converter / data merging device. A box with 2 or 3 ARINC429 channels and some software is not hard to make but would be damn hard to sell because almost nobody in the certified sphere would install it, and the homebuilt market doesn’t need it.
What you might end up doing is something like this. If/when I buy an ADL I will probably do that, and if/when I upgrade the centre stack I will make sure I have an NTSC video display capability and then anything whatever can be displayed.
The alternative, as per the link, is to fake radar or traffic data (with a custom protocol converter) but that might not be possible for displaying what the ADL produces because, I reckon, there is a limit on the number of sprites which can be defined. However the data formats for these features are confidential and may be impossible to get hold of. I have been told that a lot of even major players have reverse engineered them.
