Microsoft KB Archive/927827

Knowledge Base

Windows Vista does not enumerate an IEEE 1394a device that you connect to the computer

Article ID: 927827

Article Last Modified on 3/15/2007

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APPLIES TO

• Windows Vista Ultimate
• Windows Vista Enterprise
• Windows Vista Business
• Windows Vista Home Premium
• Windows Vista Home Basic
• Windows Vista Starter
• Windows Vista Enterprise 64-bit edition
• Windows Vista Home Basic 64-bit edition
• Windows Vista Home Premium 64-bit edition
• Windows Vista Ultimate 64-bit edition

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Important This article contains information about how to modify the registry. Make sure to back up the registry before you modify it. Make sure that you know how to restore the registry if a problem occurs. For more information about how to back up, restore, and modify the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows registry

SYMPTOMS

When you connect an IEEE 1394a device to a computer that is running Windows Vista, Windows Vista does not enumerate the device. However, if you connect the same device to a computer that is running Microsoft Windows XP, Windows XP enumerates the device successfully.

Note An IEEE 1394a device may also be referred to as a FireWire device.

CAUSE

Windows Vista only enumerates a device that sets its link status to request enumeration. If an IEEE 1394a device does not report the correct status of its link, the IEEE 1394 stack in Windows Vista does not enumerate the device.

WORKAROUND

Warning Serious problems might occur if you modify the registry incorrectly by using Registry Editor or by using another method. These problems might require that you reinstall your operating system. Microsoft cannot guarantee that these problems can be solved. Modify the registry at your own risk.

To work around this problem, for non-compliant IEEE 1394a devices, configure Windows Vista to enumerate inactive IEEE 1394 devices. To do this, follow these steps:

1. Click Start, type regedit in the Start Search box, and then click regedit in the Programs list.
   
   If you are prompted for an administrator password or confirmation, type your password or click Continue.
2. Locate and then click the following registry subkey:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\{6BDD1FC1-810F-11D0-BEC7-08002BE2092F}\ControllerInstance

   In this path, ControllerInstance represents the controller instance number. For example, this number may be 0000.
3. On the Edit menu, point to New, and then click DWORD (32-bit) Value.
4. In the New Value #1 box, type EnumerateInactiveLink, and then press ENTER.
5. Right-click EnumerateInactiveLink, and then click Modify.
6. In the Value data box, type 1, and then click OK.
7. Exit Registry Editor.

MORE INFORMATION

You may be able to obtain a firmware update for the IEEE 1394a device to resolve this problem. To determine whether a firmware update is available for the device, contact the device manufacturer or the device vendor.

For information about how to contact computer hardware device manufacturers or vendors, click the appropriate article number in the following list to view the article in the Microsoft Knowledge Base:

65416 Hardware and software vendor contact information, A-K

60781 Hardware and software vendor contact information, L-P

60782 Hardware and software vendor contact information, Q-Z

Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information. The third-party products that this article discusses are manufactured by companies that are independent of Microsoft. Microsoft makes no warranty, implied or otherwise, regarding the performance or reliability of these products.

Keywords: kbexpertisebeginner kbhardware kbtshoot kbprb KB927827

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