Changing compasses, when does COMPASS_DEV_ID change

ArduCopter Copter 3.5
1

Hello,

just a quick question:
When I change GNSS modules including compasses from different vendors, when does the parameter COMPASS_DEV_ID change?
At initial boot after the change, or in the process of a (successful) compass calibration?

Thanks

2

COMPASS_DEV_ID will be updated after every restart.