CPDLC (Controller to Pilot Data Link Clearance) and ADS B(Air Data Service)
Just to make sure all understand what this magic does it might be appropriate to get the acronyms correct.
CPDLC is Communication not clearance and is via satellite and FMC. It is via text and there are "canned" messages from the controller and a menu of " canned" responses for the crew to select.
ADS-B is Automatic Dependant Surveillance and is the way ATC tracks aircraft. With -B that is direct from the Transponder and if the transponder was off then
AFAIK, ADS-B info would no longer be available.