Pixracer PX4 external i2C mag

How can I tell if my external mag is wired up correctly? When moving from Ardupilot 2.6 to Pixracer PX4 I’m trying to reuse as much hardware as possible. I’ve got the old Neo6m on a mast with separate cables for the serial GPS and the I2C mag. I have the GPS working, but I can’t tell if I’ve got the SDC/SCL reversed on the Mag cable while I was butchering it.

cheers!
Jim

After calibration QGC should show you a panel for external mag orientation:

If there is no external compass orientation after you re-calibrated the mag then its not set up correctly.