TN3270 SSCP-LU Sessions Send x'40' Instead of Null RU (172816)


The information in this article applies to:

  • Microsoft SNA Server 3.0
  • Microsoft SNA Server 3.0 SP1
This article was previously published under Q172816
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

The SNA TN3270 Server will send an x'40' character (space) instead of a Null RU when you press the ENTER key on an SSCP screen. When this occurs, the TN3270 Client will receive the error message:
Function not supported.

CAUSE

A previous change to the TN3270 Server component caused an x'40 character, instead of an x'7d', to be sent as a null character when you press the Enter key during an SSCP-LU session. The x'40 causes the Host to send back an -RSP after a DLC Data RQD is sent.

STATUS

Microsoft has confirmed this to be a problem in SNA Server versions 3.0 and 3.0 Service Pack 1 (SP1). This problem was corrected in the latest SNA Server version 3.0 U.S. Service Pack. For information on obtaining this Service Pack, query on the following word in the Microsoft Knowledge Base (without the spaces): 
   S E R V P A C K

MORE INFORMATION

With the fix applied, Tn3servr.exe sends a Null RU to the host by default. If you need the x'40' character, you can modify the registry as shown below.

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.
  1. Start Registry Editor (Regedt32.exe or Regedit.exe, as appropriate for your version of Windows NT).
  2. Go to the following key in the registry:

    HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\TN3270\Parameters

  3. On the Edit menu, click Add Value, and use the following entry:

    Value Name: ReplaceNullRUs
    Data Type: REG_SZ
    Value: YES

  4. Exit Registry Editor.
Modification Type:MinorLast Reviewed:4/21/2005
Keywords:kbbug kbfix kbnetwork KB172816
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