UPDATE: This issue is caused by the USB to Serial Comm Port Driver. As of March 2017, after ongoing communication with the engineers at Prolific, the issue may be remedied with Driver VER-126.96.36.199 and higher. Here's a link for download':
Please be warned that counterfeit (fake) PL-2303HX (Chip Rev A) USB to Serial Controller ICs using Prolific's trademark logo, brandname, and device drivers, were being sold in the China market. Counterfeit IC products show exactly the same outside chip markings but generally are of poor quality and causes Windows driver compatibility issues. The Ultimate USB Serial Adapter. PC / Mac / Linux. Designed to make serial port expansion quick and simple. Connecting to a USB port on your Tablet PC, notebook or PC, this USB-COM Plug-in adapter instantly adds RS-232 serial communication port to your system. The product is the smallest and most flexible USB to RS-232 Plug-in Adapter. Solution 2: Update Prolific USB to Serial Drivers Automatically If you have the problem of manual downloading the USB to serial driver, you can use Driver Booster to help you. Driver Booster, a professional drivers download and update software, can scan all the missing and outdated devices drivers such as graphic, audio, USB, keyboard, speaker.
Windows Update should install this version going forward.
IMPORTANT: Driver version 3.8.12 does not support older Prolific chip versions on Windows 10 (and 8/8.1). You can DOWNLOAD THIS UTILITY from Prolific to identify your chip. Also, the PL2303 Driver Manual will provide more information about compatibility of chip versions with Windows OS Versions, including a comprehensive comparison chart.
Prolific Usb To Serial Driver 188.8.131.52
NOTE: This issue has been resolved by Prolific. Please read above. If you still have a problem, you may try this procedure to revert to a previously known working driver.
This issue is caused by the installation of an incorrect driver by Windows when it 'searches the internet for a driver.' The correct driver version for the USB to Serial Adapter is:
Prolific USB to Serial Comm Port Version 184.108.40.206
Check the driver version using Windows Device Manager. If any other version of the driver is installed, follow these instructions to install the correct version.
1. Download the correct driver
Prolific Usb To Serial Driver 220.127.116.11
Download from this link:
USB-SERIAL Driver V18.104.22.168
Unzip and run the installer, 'PL2303_Prolific_DriverInstaller_v1210.exe'.
Prolific Usb To Serial Driver 22.214.171.124 Download
Perform the remaining steps with the USB to Serial device plugged in to your selected USB port.
2. Open the Device Manager
Prolific Usb To Serial Driver 126.96.36.199 Download Windows 7
The easiest method to open Device Manager is to go to Windows Start, and in the search box, type 'Device Manager'. In the search results list, click 'Device Manager'. This dialog should open:
3. Open the Driver Properties Dialog
Double Click on 'Prolific USB-to-Serial Comm Port (COMx)' to display the Properties... click the 'Driver' tab:
4. Update the Driver
3. Click 'Update Driver', then 'Browse my computer for driver software'.
5. Select the Driver
Click on 'Let me pick from a list of device drivers on my computer'.
Select 'Prolific USB-to-Serial Comm Port Version 188.8.131.52 (3/12/2010)', then click 'Next'.
Windows will return to the Driver Properties view when the installation is completed.
NOTE: Also read Windows Update overwrites my USB2SER driver.