Microsoft KB Archive/277645

= New Hardware Attached to a Serial Port Is Not Detected When Advanced Power Management Is Enabled =

Article ID: 277645

Article Last Modified on 1/29/2007

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APPLIES TO


 * Microsoft Windows 98 Second Edition

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This article was previously published under Q277645



If this article does not describe your hardware-related issue, please see the following Microsoft Web site to view more articles about hardware:

http://support.microsoft.com/default.aspx/w98?sid=460

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit 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 attach a device to the serial port on your computer and run the Add New Hardware tool in Control Panel, the device may not be detected.



RESOLUTION
WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

To work around this issue, disable Advanced Power Management (APM) for the serial port. To disable APM for serial devices, change the data value of the EnablePowerManagement binary value in the following registry key from 01 00 00 00 to 00 00 00 00 :

HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\VxD\VCOMM

Additional query words: HWSYSAPM HWPORTS

Keywords: kbhardware kbinfo KB277645

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