For several years now, I've been using a USB-to-UART adapter that's a cheap Chinese thing that I got off eBay. I know, you can start scoffing right there, but it's been fine--has a slightly oversized USB plug which contains the electronics, and a 4-wire output with RX, TX, ground and 5V from the computer power supply. Get the right driver, and it looks like a serial port to software on the computer.
A few months ago the computer (Windows 7 in those days) gave me grief about how the interface chip in the adapter was outdated, but I got a new driver and all seemed to be well. In September I got a new computer with Windows 10, and it was still functioning. But just yesterday, the adapter wasn't recognized by the computer immediately, and then it was, but it only worked at 9600 baud and ignored software setting a different speed. I tried looking for a new driver, but couldn't change the behavior. I've got a spare identical adapter, and I plugged that in, but it worked (or failed to work) just the same. Going into the Device Manager, it's telling me "PL2303HXA phased out since 2012. Please contact your supplier" but I think that's not new: what's new is that now it's unusable! (The Pl2303hxa is the chip in the adapter.) I wouldn't have been totally surprised if the adapters had failed on Windows 10, but it's puzzling that they worked for a while and then stopped. It must have been one of those useful updates that Microsoft sends around.
Meanwhile I've got another adapter based on an FTDI chip, I think the FT232R. It's working fine. (And yes, it's a genuine chip. Good enough to work, anyway.)
The exact same item is still for sale on eBay. Looking through the listings I see some of the vendors are saying "Will not work with Windows 10", which this listing doesn't, though at least they're telling you that it's based on the PL2303HX:
https://www.ebay.com/itm/USB-To-RS2...397949?hash=item362a1734fd:g:ePkAAOSwXOVaYBv5
A few months ago the computer (Windows 7 in those days) gave me grief about how the interface chip in the adapter was outdated, but I got a new driver and all seemed to be well. In September I got a new computer with Windows 10, and it was still functioning. But just yesterday, the adapter wasn't recognized by the computer immediately, and then it was, but it only worked at 9600 baud and ignored software setting a different speed. I tried looking for a new driver, but couldn't change the behavior. I've got a spare identical adapter, and I plugged that in, but it worked (or failed to work) just the same. Going into the Device Manager, it's telling me "PL2303HXA phased out since 2012. Please contact your supplier" but I think that's not new: what's new is that now it's unusable! (The Pl2303hxa is the chip in the adapter.) I wouldn't have been totally surprised if the adapters had failed on Windows 10, but it's puzzling that they worked for a while and then stopped. It must have been one of those useful updates that Microsoft sends around.
Meanwhile I've got another adapter based on an FTDI chip, I think the FT232R. It's working fine. (And yes, it's a genuine chip. Good enough to work, anyway.)
The exact same item is still for sale on eBay. Looking through the listings I see some of the vendors are saying "Will not work with Windows 10", which this listing doesn't, though at least they're telling you that it's based on the PL2303HX:
https://www.ebay.com/itm/USB-To-RS2...397949?hash=item362a1734fd:g:ePkAAOSwXOVaYBv5