USB to Serial Support for Windows

Verify the Driver Installation:

1. Go to the Device Manager:
• Windows 7: Start -> Control Panel -> System & Security -> Device Manager
• Windows Vista: Start -> Control Panel -> System & Maintenance -> System -> Device Manager
• Windows XP: Start -> Control Panel -> System -> Hardware -> Device Manager
• Windows 2000: Start -> Settings -> Control Panel -> System -> Hardware -> Device Manager
• Windows 98/ME: Start -> Settings -> Control Panel -> System -> Device Manager
2. Click on the plus sign (+) next to "Ports."
3. If the device is installed properly, you will see "Prolific USB to Serial Com Port."

The driver is installed properly, but the device is not working:

The most common reason that a device such as a PDA, GPS, cell phone, etc. would not work with a USB to Serial adapter when everything appears to have installed fine is that some devices will only scan a limited number of COM ports.

For instance, it is very common for a PDA to have a limitation of scanning the first four (or sometimes two) COM ports. If the adapter is installed on COM5, a device with such a limitation will not work until the COM port is reassigned to COM1 - COM4.

How do I change the COM port on my USB to Serial adapter?

Windows XP, 2000, ME, and 98 include a function that allows you to reassign the COM port. Simply follow the instructions below:

Windows 7, Vista, and XP

1. Follow steps 1 and 2 in "How to Check the Driver Installation."
2. Right click on the "Prolific USB to Serial Port" and click on Properties
3. Click on the "Port Settings" tab. Click the "Advanced" button.
4. Pull down the scrollbar on the bottom, left side and select COM 1, 2, 3 or 4 (NOTE: Choose one that does not say "in use" next to it). Click "OK."
5. Click "OK" again. Notice that the device will show up as being on the same COM port that it was before (i.e., COM5), but will show up on the new port if you close the Device Manager and open it again.
6. Close the device manager. You may have to run the software that came with your device to make it rescan the COM ports.

Windows 2000, ME, and 98SE

1. Follow steps 1 and 2 in "How to Check the Driver Installation."
2. Right click on the "Prolific USB to Serial Port" and click on Properties
3. Click on the "Port Settings" tab. Click on the Resources tab.
4. Uncheck the box that says "Use automatic settings".
5. Select "Input/Output range". Click on "Change Settings".
6. Type "02E8-02EF" in the Value box. This value will change the port to COM 4. If COM 4 is in use, you must choose another port. The values for each port are:
• COM 1: 03F8-03FF
• COM 2: 02F8-02FF
• COM 3: 03E8-03EF
• COM 4: 02E8-02EF
7. After entering the value, click OK. Click OK again and click Yes when the "Creating a Forced Configuration" window appears. Click OK again.
8. Restart your computer. If you go into the device manager, you will see that the COM port has changed to the one you have selected.

Other Problems:

If you are having problems with the USB-to-Serial Adapter in Windows that this page does not address, please contact us at support@sewelldirect.com or call (800)709-1345 between 8 AM - 5 PM MST.

source : http://sewelldirect.com/support/usbtoserialsupportwindows.aspx