USB adapter no longer works

Thread Starter

John P

Joined Oct 14, 2008
1,785
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A few months ago the computer (Windows 7 in those days) gave me grief about how the interface chip in the adapter was outdated, but I got a new driver and all seemed to be well.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-RS232-TTL-UART-PL2303HX-Auto-Converter-USB-to-COM-Cable-Adapter-Module/232634397949?hash=item362a1734fd:g:ePkAAOSwXOVaYBv5
 

be80be

Joined Jul 5, 2008
1,971
Have you tried this
http://www.prolific.com.tw/US/ShowProduct.aspx?p_id=225&pcid=41

Windows Vista/7/8.1/10 (32 & 64-bit) WDF WHQL Driver: v3.8.31.0 (08/11/2019) / v5.0.8.0 (07/03/2019)
- Windows 10 Certified WHQL Driver (TH1 1507, TH2 1511, RS1 1607, RS2 1703, RS3 1709, RS4 1803,RS5 1809 , 19H1 1903 versions)
I have 1903 ver on windows 10 it works on it I did have to change drivers but i dont use prolific usb to serial much it worked a month ogo tho.
I use the ch340 I make my own for the esp I by the bare modulate.
 

Thread Starter

John P

Joined Oct 14, 2008
1,785
Thank you for the link, be80be. That material was certainly the most extensive set of files I've seen about the Prolific USB interface chips, but the driver there didn't cure the problem. There are different variants of the actual chip in the adapter, and I seem to have an outdated one that won't function on Windows 10. Just as a control, I fired up my retired Windows 7 computer and plugged in one of the adapters, and it worked perfectly, just as it always did. So it's obviously a Windows 10 issue, though why the adapters worked on Win10 for a while and then quit remains mysterious. One of those mysteries that will remain unsolved, I suppose.
 

be80be

Joined Jul 5, 2008
1,971
Windows 10 can be hard on stuff I loaded a driver for ST board that has serial over USB it killed my wireless keyboard dead My take is the S&T chip
maybe in the USB dongie is close match but I've removed the driver it still installs it
 
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