Aren't we just debating semantics or terminology, at least to a large extent though?
My picture (which CBW of course) is that when the current direction is read the voltage at the wiper relative to common is 'measured' (which should be equivalent to measuring the resistance) and eg applied to an A/D converter. Why does it matter whether that voltage is derived from the ISS supply voltage or effectively emulated by a different type of anemometer as long as both are referenced to the same ground? Of course the reference/supply voltage might not be exactly 3.00V for both voltage sources and so is a potential source of error, but at a guess both will be 3.0±0.1V or better and so won't be a major source of error in the context of direction. And maybe the circuitry of a well-designed alternative anemometer could provide a correction even for that discrepancy.
It's not "the voltage at the wiper relative to common is 'measured' (which should be equivalent to measuring the resistance)".
It's the voltage at the wiper as a
percentage of the total voltage across the potentiometer.
Assume, for instance, that the Davis solar panel is powering the SIM and the solar panel voltage is 2.8 volts - and the anemometer direction signal is supplying 2.95 volts. What's the direction of the wind? [NOTE: This is just an example - I have been asking for more information, as you know]
But it's not just semantics or terminology - especially in the case where the anemometer is being powered by an external 12V supply. The anemometer will have internal circuitry with voltages referenced to the anemometer common. The SIM will have internal circuitry with voltages referenced to the ISS common. You said: "as long as both are referenced to the same ground", and that may be a very important point -
if the anemometer is supplying a voltage, rather than a resistance (potentiometer) that does not have a common/ground reference (like the Davis anemometer).
Also, do the anemometer and the ISS have a "frame ground" in any situation? Like an external power supply for the ISS? What if those "frame grounds" are actually connected together, by mounting them on the same tower, or .......
And finally, the above discussion is where the
cabled VP2 differs significantly from the wireless model. The cabled VP2 clearly has a "common reference" (one of the wires from the console to the ISS).
There are a lot of variables here - I'm not saying there's anything amiss. But the "wireless VP2" and "anemometer supplied by an external 12V source" has been reported here as having problems. That would be understandable if (for instance) that anemometer is truly supplying a 0-3V directional signal, (with perhaps a common reference different from the SIM).
One key question (in my opinion) would be whether the anemometer direction can be measured with an ohmmeter.
