If dealing with Windows and Serial Port communications isn't bad enough, I cant' even seem to come close when trying to implement a solution using completion routines and the WriteFileEx and ReadFileEx functions. Am simply trying to have both read and write fucntions as overlapped IO using these functions and completion routines. At the risk of making it sound like I change oil at a Jiffy Lube for a living and have no idea what I'm doing on a computer, this is a real pain in the rear. Does anyone have a code snippet that does serial port communications using overlapped IO, completion routines and WriteFileEx and ReadFileEx?? Help...