Very interesting, thanks @Tom Stian
I see that in my capture sim/cockpit2/gauges/indicators/wind_speed_kts exactly matches the indication in the EHSI (obvious). Soooo, isn't a IXEG bug.
Now it's clearer and ... now I'm more confused.
Why is it so different and weird, almost always about a half?
The direction of the wind does not seem to be the factor, because in both dataref sim/weather/ and sim/cockpit2/gauges/indicators the deg are almost equal.
Mysteries of the X-Plane?
I will contact the author of FS-FlightControl commenting on that other dataref. As I said, the air speed indicated on the screen in his program is another.
It's clear to me that IXEG is reading the correct data ... but (I think) FS-FlightControl too, and that is not possible.
Note: Apologies for the excess of emoticons, but it helps me overcome my insecurity with English and clarify the meaning of my sentences.