Hi
Welcome to Mobiflight !
We got multiple Input ways here.... Cause there are also lots of ways to build it!
In real Aircrafts and also in High Professional Homecockpits the Flaps lever (B737) is NOT a Poti.... Its a mechanical Build with a Springloaded Pull Handle, a Frame that limit your moving ways ( To be threated to set some positions before be able to set another one) and finally single "Buttons" in the Nodges of the Flaps Position.
See it like a row of Buttons where always the Button your handle stay at the moment is pushed by the latching handle down.
For THIS system the Input from PMDG is perfect.... Cause we like to SET the Flaps exactly to the specific Position.
But sure. Also a lot of People use a Poti here.
The Most easy way to do this is via Sim Controlls. Cause you can set a Joystick Axis already in Sim (FS2020 Controlls) to the Flaps.
That means your Poti must be a HID Controller ( Not a Mobiflight Device) or you could use "VJOY" to execute a Mobiflight Poti into a Virtual Joystick.
Another way is to use Mobiflight but directly set the Sim Flaps instead of the PMDG Events.
Please check "Generic" Events (Via Simconnect WASM) . There is a "Flaps Set" Variable you can use.
As you expect. Maybe a deeper formula is needed cause your Flaps are not Linear.... The Moving of Handle between 0 and 15 is maybe the same like from 15 to 40
So we can not simply send 0-100% cause the areas are different.
Means if using a Axis Input not work as expected then we need to split the Axis into "areas" and send for each Area the SET Commands we talk above (buttons).
OR we send a sepcific Value like 5%, 12%, 18 % and so on for the position we are ( Interpolation)
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At the End.... I recommend to join our Discord and ask this in the PMDG Sub Channel .....
https://discord.gg/99vHbK7
There advanced users (who build already the flaps) can guide you!