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How to Make Windows Re-Detect COM, LPT and USB Ports

Document relates to:   LapLink Gold 11.5, LapLink Classic, LapLink Gold 11.x, FileSync, LapLink for Win95, LapLink Technical, LapLink Professional, LapLink Gold, LapLink NT, Cables, LapLink 2000

 

SUMMARY

I am having problems connecting and I want to make sure that Windows is correctly recognizing the ports on my computer. How do I do this?

 

SOLUTION

Important: The following steps are safe, provided that your ports are functional, and enabled in the system BIOS. The goal of this procedure is to repair (‘refresh’) the Device Manager entries, and to diagnose hardware problems. This procedure will determine if the ports themselves can be re-detected by Windows Plug ‘n’ Play. If they are not re-detected, Laplink technicians will be unable to guide you through the system BIOS; instead, please contact your PC manufacturer for assistance.

For Windows 95, Windows 98, and Windows Millennium

Note: Please follow only the relevant portion of these steps. For example, if you connect with just USB ports, you can skip the steps for COM and LPT ports.

  1. Follow the steps in Technical Document 102: How do I Boot to Safe Mode? to boot the computer to Safe Mode.

  2. Right-click My Computer, click Properties and then the Device Manager tab.

  3. Click the + sign before Ports (COM and LPT).

  4. Highlight each COM or LPT port and click Remove.

  5. Click the + sign before Universal Serial Bus Controllers.

  6. Highlight all PCI-to-USB Host Controllers, all USB Root Hubs and click Remove.

    7. Note: If any USB devices, such as a camera or printers have been installed, they will be removed automatically. Remove their cables from the computer. Reinstall them after Laplink connects.
  7. Reboot the computer. During the reboot, you may see Windows display an Adding New Hardware dialog.

  8. Return to Device Manager to check the new ports.

    9. Note: After reboot, if any ports have a red X or a yellow ! , then Windows did not correctly detect the ports. Try these steps again and consider the possibility that problems exist in the computer's BIOS or that the ports may be physically damaged.

For Windows 2000 and Windows XP

Note: Please follow only the relevant portion of these steps. For example, if you connect with just USB ports, you can skip the steps for COM and LPT ports.

  1. Follow the steps in Technical Document 102: How to do I Boot to Safe Mode? to boot the computer to Safe Mode.

  2. Right-click My Computer, click Manage and then Device Manager.

  3. Click the + sign before Ports (COM and LPT).

  4. Highlight each COM or LPT port and click Remove.

  5. Click the + sign before Universal Serial Bus Controllers.

  6. Highlight all PCI-to-USB Host Controllers, all USB Root Hubs and click Remove.

    7. Note: If any USB devices, such as a camera or printers have been installed, they will be removed automatically. Remove their cables from the computer. Reinstall them after Laplink connects.
  7. Reboot the computer. During the reboot, you may see Windows display an Adding New Hardware dialog

  8. Return to Device Manager to check the new ports.

    9. Note: After reboot, if any ports have a red X or a yellow ! , then Windows did not correctly detect the ports. Try these steps again and consider the possibility that problems exist in the computer's BIOS or that the ports may be physically damaged.


For Windows NT
  1. From the Windows Start menu, go to Settings and click Control Panel.

  2. Double-click Ports.

  3. Highlight each COM port and click Delete.

  4. Reboot the computer.

  5. Return to Control Panel and Ports to check the new ports.

  6. Highlight each COM port , click Settings and then Advanced.

  7. In the Base I/O field, change the current default address as follows:

      8. COM1 ... change to 3F8
      COM2 ... change to 2F8
      COM3 ... change to 3E8
      COM4 ... change to 2E8

  8. In the Interrupt Request field, change the current default setting as follows:

      9. COM1 ... change to IRQ 4
      COM2 ... change to IRQ3
      COM3 ... change to IRQ 4 (or other IRQ if you know how the port is specifically configured)
      COM4 ... change to IRQ 3 (or other IRQ if you know how the port is specifically configured)

  9. Reboot the computer.

    10. Note: After reboot, if ports are not redetected, try the steps again and consider the possibility that problems exist in the computer's BIOS or that the ports may be physically damaged.


 

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Keywords:   Cable: Parallel, Cable: Serial, Cable: USB (original), Cable: USB Network (gold), Connections: Cable, Configuration: COM ports, Configuration: Ports, Cable: USB Network, How To: Windows

Platforms:   WinXP, WinMe, Win98/SE, WinNT, Win2K, Win95

 

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Last updated: Wednesday, October 08, 2008

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