2.COM10以上的端口采用 “COMX”或“COMX:”名不能打开串口，命名为“\\\\.\\COMX”打开成功。

MSDN看到的描述：

If your com port is greater than 9, trying to open e.g. "COM10" will fail... This is documented above, but there is a subtlety with using the syntax specified:

"\\.\COM10" must be in your code as "\\\\.\\COM10":

sprintf(tmp,"\\\\.\\COM%d",comport);

CreateFile(tmp,GENERIC_READ|GENERIC_WRITE,0,NULL,OPEN_EXISTING,0,NULL);

This may also apply to other versions of Windows(?)