In order to use your USB to serial cable, you need to install the driver first. Visit the following official website in order to find out if your device is compatible with the OS that you are using. If you can't find it on the list from the site it's a big chance that you will not be able to use it. However, you can visit the manufacturer's official website in order to download the appropriate software. If you can't find the driver there, contact the manufacturer for more information.
