it is not powered from nmea2000... it will have a power plug
, and a nmea 2000 plug
the nmea 2000 backbone will also need power.
if the unit ever dies, and all your phones and ipads die, and everything else. and you have to resort to using the mag compass
to get somewhere. unbolt the display and put it somewhere else...
if it's close it'll likely move the compass. take a reading before and after install, and with it powered on and off. and you'll see if it changes anything.