You'll have to get the manual for BOTH the Princeton/RED sender, AND the MGL MX1. The sender can output several different ways. The "Calibration" the sender talks about is a way of setting the sender, and in certain modes, calibrating the "Set Points". HOWEVER, with my Dynon, it's looking for a 0-5v signal, and you calibrate at the EIS, with the sender set to the default, continuous analog output mode. Carefully read the INSTALLATION manual for the MX1, and it will give you the clues you need.
Here is the installation manual for your MGL MX1
https://www.mglavionics.co.za/Docs/iEFI ... manual.pdfFrom the RED installation manual (
https://www.redavionics.com/instructions)
"Your fuel probe can be configured as 1, 2, or 5 set
points.
1 set point is helpful if you are connecting the probe
to an EFIS that has its own calibration.
2 set points is typically used for uniformly shaped
tanks where the amount of fuel in the tank directly
correlates to the amount of the probe that is covered
by fuel.
5 set points is for complex tank shapes where, for
example, the top portion of the tank is larger than the
bottom portion."