Dear All,
I've solved this issue. It has nothing to do with the ported usb_dev_comp_mouse_ser running on C6748. The root cause is: On PC Host program the COM port name passed to CreateFile() should be different form "COM*" if COM port is greater than COM9. The following link describes this rule:
http://support.microsoft.com/kb/115831/en-us
For example, if I want to open COM10, then the name passed to CreateFile() should be "\\\\.\\COM10", rather than "COM10".
Just for your reference in case you are interested.
Regards,
Oliver