Forget using the USB serial cable with prolific chip and use a USB2EQ5 cable ( available from Bintel )
Those serial cables are hit and miss especially with the prolific chip set
I tried 2 or 3 different brands $30 to $70 and they all failed
The EQ direct cable USB2EQ5 cable and it’s associated driver has worked perfectly every time I connect both my HEQ5 and EQ6-R mounts with EQMOD
Shoestring Astronomy Virtual Com Port ( VCP driver for FTDI chip )* for your Bintel USB2EQ5 cable (
www.shoestringastronomy.com ) This is the most important item and allows your Laptop to find and connect to the mount .Hopefully your operating system is on the list for the VCP driver ( Go to The Shoestring Astronomy Store then downloads then Virtual Com port drivers for USB2EQ5 ( VCP Driver for FTDI devices ) your USB2EQ5 cable has a FTDI device in the USB end
Cheers