Microsoft KB Archive/164390

= Windows NT Appears Not to Send the DTR Signal to a UPS on Shutdown =

Article ID: 164390

Article Last Modified on 11/1/2006

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APPLIES TO


 * Microsoft Windows NT Workstation 3.51
 * Microsoft Windows NT Workstation 4.0 Developer Edition
 * Microsoft Windows NT Server 3.51
 * Microsoft Windows NT Server 4.0 Standard Edition

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This article was previously published under Q164390



IMPORTANT: This article contains information about editing the registry. Before you edit the registry, make sure you understand how to restore it if a problem occurs. For information about how to do this, view the "Restoring the Registry" Help topic in Regedit.exe or the "Restoring a Registry Key" Help topic in Regedt32.exe.



SYMPTOMS
When Windows NT goes through the shutdown process after a low battery message, it appears that Windows NT does not send a DTR signal and the UPS does not power off.



CAUSE
Windows NT waits approximately 2 minutes before sending out the DTR signal, allowing enough time for programs and services to shutdown properly. It is possible that the UPS will run out of power and perform a manual shutdown before Windows NT sends the DTR signal.



RESOLUTION
It is possible to change the amount of time that elapses from when the Low Battery message is sent and when Windows NT sends out the DTR signal. You can use Registry Editor (Regedt32.exe) to add an entry to the registry.

NOTE: You must be logged on with administrative permissions to alter certain registry settings.

WARNING: Using Registry Editor incorrectly can cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that problems resulting from the incorrect use of Registry Editor can be solved. Use Registry Editor at your own risk.

For information about how to edit the registry, view the "Changing Keys And Values" Help topic in Registry Editor (Regedit.exe) or the "Add and Delete Information in the Registry" and "Edit Registry Data" Help topics in Regedt32.exe. Note that you should back up the registry before you edit it.

To specify a shut down wait, perform the following steps:
 * 1) Start Registry Editor (Regedt32.exe) and go to the following subkey:


 * 1) From the Edit menu, click Add Value. Type the value ShutdownWait with a REG_DWORD value in seconds between zero and 600 decimal.
 * 2) Quit Registry Editor and restart your computer for the changes to take place.



MORE INFORMATION
For more information, please see the following article in the Microsoft Knowledge Base:

ARTICLE-ID: 98885

TITLE : Pin Connections for Cabling Between APC UPS and RS-232

Additional query words: APC UPS battery backup supply

Keywords: kbhardware kbprb KB164390

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