USB to Serial Adapter Troubleshooting

• Use a "real" RS-232 serial port, if available, in preference to a USB to Serial Adapter.
• Verify that the USB to Serial Adapter's device driver is up-to-date. To determine the currently installed device driver's version:
  • Plug the USB to Serial Adapter into a USB port on your computer
  • Open the "Start" menu
  • Right click "My Computer" or "Computer"
  • Select "Manage"
  • In the Computer Management left pane, select "Device Manager"
  • In the right pane, select the "+" next to "Ports (COM & LPT)" to expand the Ports list
  • Double click the COM port entry for your USB to Serial Adapter. The Elecraft KUSB appears as a "Prolific USB-to-Serial Comm Port".
  • The "Driver" tab contains the "Driver Version". If you're using an Elecraft KUSB or other Prolific chip set USB to Serial Adapter cable, this Driver Version must be version 2.0.2.1 or later, and version 2.0.2.8 or later is recommended.
  
• If your Prolific device driver is earlier than version 2.0.2.1, update it to the current level by visiting the manufacturer's support web site. The Elecraft KUSB driver can be updated from http://www.prolific.com.tw/eng/downloads.asp?ID=31. The chip set in KUSB units sold before mid-2010 is a Prolific Technology, Inc. PL-2303.
  Recent KUSB USB to Serial Adapters labeled "Sabrent" may use an FTDI chip set, and the driver diskette accompanying the KUSB contains suitable device drivers.
  Use the Windows Device Manager to determine the chip set used in your KUSB.
• After installing the new device driver, take a moment to verify that it was actually installed by viewing the Driver tab again. If the new driver did not install, it may be necessary to uninstall the old device driver before installing the new driver. If a Prolific Driver has already been installed, you may need to run the new driver installer twice. The first "installation" seems to only remove the old driver. Run the installer again to install the new driver.
• Try a different USB port on your computer.
• Try a different USB to Serial Adapter.
• Try a different computer. Some combinations of USB to Serial Adapter and USB port are more reliable than others. For example, some laptop computers may not provide sufficient power to USB devices for reliable communications.
• One user reported that his USB to Serial Adapter did not work well when connected through a USB Hub.
• Some users have found better results with separately powered USB hubs rather than those that receive power from a USB port.
• A laptop computer's USB port may work more reliably if the laptop is powered by a power supply rather than its batteries.