The PL2303 based USB to serial are a real problem, I have had many of them and almost every one has been thrown in the bin!
The problam is that nowadays they are nearly all Chinese clones that do not work reliably with modern Windows versions.
One of my customers had several systems that used a USB to serial adapter which was PL2303 based, and started having issues when they 'upgraded' from Windows 7 to Windows 10.
I spend a lot of time with him trying to find out what the issue was, their system had the USB to serial in an always up 19200 baud link and intermittently the link would drop and then stop receiving, he was adamant it 'is not the adapter, we've used them for years without any issue'.
After much testing, I found the adapter would not receive at all at 115200 baud, below that it became more reliable the slower the baud rate, at 1200 baud, I could not get it to fail.
We swapped the adapters out for initally FTDI ones, and the problem went away, since then we've tried the CH340 based ones which are much cheaper , they too work perfectly well at 115200 baud which I think is what is used by the G90 / X5105.
Tony G1HMO
