LU3 Printing: Print Data May Overwrite Previous Line of Data

ID: Q225471

The information in this article applies to:

Microsoft SNA Server, versions 3.0, 3.0SP1, 3.0SP2, 3.0SP3, 4.0, 4.0SP1, 4.0SP2

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

An LU3 print job processed through SNA Server's Host Print Service may result in output that has data printed on top of previously printed lines of data. For example, data that is supposed to print on the fourth line of a page may be printed on top of the data printed on the third line of the page.

This problem is only likely to affect a few lines of data in a print job.

CAUSE

Print server does not issue an automatic New Line (NL) command for LU3 print jobs when a line of data reaches the Maximum Print Position (MPP) or Default Page Width if the character at print position MPP + 1 is a NL, Carriage Return (CR), or End of Medium (EM) command.

If the character at position MPP + 1 is a CR, the data intended for the next print line will print over the data on the current print line as the CR does not cause the print position to move down to the next print line.

This behavior is by design as described below.

RESOLUTION

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. If you are running Windows NT, you should also update your Emergency Repair Disk (ERD).
The following registry entry can be added to force print server to always issue the automatic NL when a line of data reaches the MPP.

Start Registry Editor (Regedt32.exe).

Locate the following key in the registry:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SnaPrint\Parameters

On the Edit menu, click Add Value, and then add the following registry value:

Value Name: AlwaysDoNL
Data Type: REG_SZ
Value: True

Quit Registry Editor.

MORE INFORMATION

The MPP or Default Page Width is used to specify the number of characters per print line. SNA Server allows values of 1 to 255 to be configured for a print session in SNA Server Manager. Typically, values for 3270 printing are 80 and 132. The MPP value for a given LU3 print session or print job can be set by one of the following methods listed in order of precedence:

Write Control Character (WCC) byte (Bits 2 and 3) within the 3270 data stream.
In a Printer Definition Table (PDT), using the MAXIMUM_PRINT_POSITION session parameter.
SNA Server Manager Print Properties value.

When Print Server determines that the MPP has been reached for a particular line of print data, it will issue an automatic NL command to make sure the print position is moved down one line before printing any additional data. An exception to this rule exists for LU3 printing when the print data contains a NL, CR, or EM command at MPP + 1. In these cases, the automatic NL is cancelled, and the subsequent NL, CR, or EM command is executed.

If an NL command is present at MPP + 1, suppressing the automatic NL insures that two NL commands are not issued.

If a CR command is present at MPP + 1, the suppression of the automatic NL allows a way to provide bold or underline printing in an LU3 print job that normally does not allow this type of advanced print function. The CR command returns the print position to the beginning of the current print line. If the print job included the same print data, the result would be bold print. If the print job included underscore (_) characters, the result would be underline print.

If the EM command is present at MPP + 1, the suppression of the automatic NL just allows the EM command to be processed without moving down one print line. The EM command is used to signify the end of the screen of print data. LU3 printing is processed as screens of data much like 3270 display sessions are screen oriented. This allows the next "screen" of data to begin printing where the prior "screen" ended, preventing a possible formatting problem.

Additional query words:

Keywords :
Version : WINDOWS:3.0,3.0SP1,3.0SP2,3.0SP3,4.0,4.0SP1,4.0SP2
Platform : WINDOWS
Issue type : kbprb