No, the Windows PC was only for testing and verifying that the RS485 Connection workes well.
My preferred solution would be this stick at the Raspberry Pi which is running the FHEM. Therefor I'd need a module to read the stream and interpret it in the FHEM format. Problem: I've never written a module. It would be possible somehow.. in some month.
The alternate solution would be your mysensor system. Especially because its running and tested. Problem: The Hardware. I have no experience in arduino and absolutly no idea how to build such a board. Thats why I thought I could plug the stick to an arduino and make it magicly work.
EDIT: Ok. It is easier than I thought to write this module. I'm working on it and the main functions should be finished this week. I'll publish it, if it is ready for testing.