Hi Angelo,
the control range can neither be set on the Genos nor on the FC7. When the keyboard is powered on, the polarity of the connected expression pedal (e.g. the FC7) is automatically recognized, and the control range is set based on the resistance of the built-in potentiometer (with the FC7: 50kOhm). The latter always goes from "zero" to "full". (When the FC7 is used to control the volume, the volume when the pedal is fully depressed is the same as when the pedal is not connected.)
By the way: Most users want a wide (long) control range for a volume pedal. I also work with the FC7 (on Genos and Tyros5), with which I only control the volume of the RIGHT parts. I think the control range of the FC7 is optimal. Normally, in live operation, the volume is not always adjusted from "zero to full", instead I usually play with the pedal 50% - 80% depressed. This means I always have some reserve for loud accents. I also use the aforementioned control range for organ voices. I rarely play with a pedal position below 50% of the control range, i.e. with less than half the possible volume.
P.S.
It makes no difference which absolute resistance value the potentiometer of the expression pedal used has (e.g. 10, 12, 25, 50 or 100 kOhm.) The potentiometer works here as a so-called "voltage divider" circuit, i.e. as already mentioned, the resistance value is determined when the keyboard is powered on and then the control range is internally adjusted so that the pedal can always be used to control from "zero" to "full".
Best regards,
Chris