Microsoft KB Archive/938645

= You cannot communicate with the local device by using a redirected COM port in a Windows Server 2003-based terminal-server session =

Article ID: 938645

Article Last Modified on 10/11/2007

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APPLIES TO


 * Microsoft Windows Server 2003, Standard Edition (32-bit x86)
 * Microsoft Windows Server 2003, Web Edition
 * Microsoft Windows Server 2003, Enterprise Edition
 * Microsoft Windows Server 2003, Datacenter Edition (32-bit x86)
 * Microsoft Windows Server 2003, Standard x64 Edition
 * Microsoft Windows Server 2003, Enterprise x64 Edition
 * Microsoft Windows Server 2003, Datacenter x64 Edition
 * Microsoft Windows Server 2003, Enterprise Edition for Itanium-based Systems
 * Microsoft Windows Server 2003, Datacenter Edition for Itanium-Based Systems

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SYMPTOMS
Consider the following scenario. You create a terminal-server session from a client computer to a Microsoft Windows Server 2003-based terminal server. A device is connected to a COM port on the client computer. However, you cannot use the redirected COM port in the terminal-server session to communicate with the device.

For example, if a printer is connected to the COM port on the client computer, you cannot print documents by using the redirected COM port. This problem occurs if the following conditions are true:
 * An application transfers data by using a redirected COM port in a terminal-server session.
 * The application uses the _fsopen function or other related functions to transfer data by using the redirected COM port.
 * The application is compiled by Microsoft C++ compilers.



CAUSE
This problem occurs because the GetFileType function cannot determine the correct device type for the redirected COM port. When an application communicates with the redirected COM port, the application may use the _fsopen function or other related functions to open file streams. In Microsoft Visual C++, these functions are used to call the CreateFile function and the GetFileType function.

The GetFileType function cannot determine the correct device type for the redirected COM port. Instead, the GetFileType function returns a FILE_TYPE_UNKNOWN value. Therefore, the _fsopen function fails.



Hotfix information
A supported hotfix is now available from Microsoft. However, it is intended to correct only the problem that is described in this article. Apply it only to systems that are experiencing this specific problem. This hotfix may receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next Windows Server 2003 service pack that contains this hotfix.

To resolve this problem immediately, contact Microsoft Customer Support Services to obtain the hotfix. For a complete list of Microsoft Customer Support Services telephone numbers and information about support costs, visit the following Microsoft Web site:

http://support.microsoft.com/contactus/?ws=support

Note In special cases, charges that are ordinarily incurred for support calls may be canceled if a Microsoft Support Professional determines that a specific update will resolve your problem. The usual support costs will apply to additional support questions and issues that do not qualify for the specific update in question.

Prerequisites
To apply this hotfix, you must have Windows Server 2003 Service Pack 1 or Windows Server 2003 Service Pack 2 installed on the computer. For more information, click the following article number to view the article in the Microsoft Knowledge Base:

889100 How to obtain the latest service pack for Windows Server 2003

Restart requirement
You must restart the computer after you apply this hotfix.

Hotfix replacement information
This hotfix does not replace any other hotfixes.

File information
The English version of this hotfix has the file attributes (or later file attributes) that are listed in the following table. The dates and times for these files are listed in Coordinated Universal Time (UTC). When you view the file information, it is converted to local time. To find the difference between UTC and local time, use the Time Zone tab in the Date and Time item in Control Panel.

Windows Server 2003 with Service Pack 2, x64-based versions


WORKAROUND
To work around this problem, use other types of redirected ports instead of a redirected COM port. For example, use a redirected LPT port or a redirected USB port.



STATUS
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the &quot;Applies to&quot; section.



MORE INFORMATION
For more information, click the following article number to view the article in the Microsoft Knowledge Base:

824684 Description of the standard terminology that is used to describe Microsoft software updates

Additional query words: TS print 2003 c5 COM redirection

Keywords: kbbug kbfix kbqfe kbpubtypekc kbexpertiseinter kbhotfixserver kbwinserv2003postsp2fix KB938645

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