I have seen many programs that communicate to Windows via UDP, like UDPSpeed that shows IL-2 flight sim gauges. The app sends and receives small packets and uses the data to present graphics.
So, write your own app that does the same thing (except, obviously it isn't L-2 flight sim packets that you want).
So why can't the same or similar app simply route the messages to and from a COM port instead of present graphics?
Why can't Flight Simulator actually fly my airplane to the moon. Because it wasn't designed to do that. Neither Flight Simulator or my airplane (if I actually had one).
Now, your app MIGHT be designed to actually (try to) fly my airplane to the moon. I don't know, because you haven't written it yet.
Or is there some reason why the same PC program can't do both UDP and serial COM that can do both UDP and graphics?
Is there some reason Flight Simulator can't actually fly my airplane to the moon? Because no one thought that making it capable of doing so was necessary.
I can see that there will be some extra interface just to tell it which COM port to read/write but honest, the other end is there this time in IL-2 devicelink.
Can I have a hit of whatever you're smoking?