We had a similar device on VC9 (Vanguard) freighters.
Oleo pressure was sensed from the nose & both main gears. Knowing the cross sectional area of the gear struts allowed STAN to calculate the weight, and by using some simple internal processing, it could calculate the C of G expressed as % MAC.
It proved invaluable on at least one occasion when pallets 1 -9 had been loaded 9 - 1 and the C of G was way out of limits.
STAN Link
Apparently, you have to dial in the weight in lbs and the CG in %MAC yourself.
That may be part of the initial set up & calibration.