If your hardware has an FTDI based USB to TTL logic level transceiver, examples using chips like FT232R, FT245R FT2232 and you’re having difficulty communicating through the COM port on your computer you may need to install drivers from FTDI.
In many cases these days the drivers will be pre-installed and be relatively plug-and-play, however, if you’re using an outdated version of Windows it is very likely you will need to install the drivers for the chip on your OS. Otherwise corrupted drivers could also be the issue which also would be advisable for re-installing these drivers.
Those drivers and installation guides can be found on FTDI’s website by clicking here.
Drivers for Virtual Com Ports can be found by clicking here.
Application Notes on installing drivers and modifying FTDI Device Settings can be found here in document AN_107