I noticed on B737-800 entering the flight deck on the right side there is a port Data Loader and I think this is the Flight Acquisition Unit.
Is this port used exclusively for loading data to FMCs etc or it can also read data? Does the aircraft "stream" data through this port? If yes, which protocol is used? I am trying to understand if it works like OBD-II we have in cars. Obviously not exactly the same, but is it similar? Does it stream live data?