Hello,
Making progress, incidentally I got stuck with defective converter and marginal CP2101 that could not get up to speed… @LuisVale , yep good old AliExpress got me again with half of my parts defective… So for everyone interested experimenting, getting the JDRONE prebuild and working units may be a better alternative 
@olliw42 I got 2 units working OK as SLSCAN so I can see the PixHawk on the GUI.
Now, I want to modify on of the unit as a Magnetometer Node, I tried to flash the boot loader but I cannot see the node with the slscan, I tried flashing the uc4h-gpsmagbaro-v026.hex , but no success, Am I missing something here ?
Here is my setup ( as you can see , I replace the CP2101 with FTDI units)
