Err: Cannot Write to LPTx Printing to Parallel Port
ID: Q181022
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The information in this article applies to:
-
Microsoft Windows NT Workstation version 4.0
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Microsoft Windows NT Server version 4.0
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Microsoft Windows NT Server version 4.0, Terminal Server Edition
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 on how to do this, view the "Restoring
the Registry" online Help topic in Regedit.exe or the "Restoring a Registry
Key" online Help topic in Regedt32.exe.
SYMPTOMS
When you print to a parallel port on a computer running Windows NT, one of
the following may occur:
- After you clear a paper outage or jam on the printer and click OK on the
following error message, the same error may reappear until Windows NT is
shutdown and restarted:
Cannot write to LPTx
where x is the LPT port number.
- On host-based printers, the printer does not reset properly if you
shutdown and restart Windows NT without first actually powering off the
computer.
- When you print with an older parallel port printer, the output has
invalid, garbled, or missing characters or nothing prints.
CAUSE
The first two symptoms above are caused by the local port monitor resetting
faster than the port can become ready. The printer driver then interprets
that the printer is properly reset, which is not the case.
The third symptom happens because the centronics handshake in
Parallel.sys is too aggressive for some older devices.
RESOLUTION
To do a slower handshake to older/slower printers, the following registry
entry must be added.
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 registry entry to enable this feature is
\HKLM\SYSTEM\CurrentControlSet\Services\Parallel\Parameters
and is a DWORD value "UsePIWriteLoop", which needs to be set to 1.
Be aware that enabling this entry will slow down ALL parallel ports.
To resolve this problem, obtain the latest service pack for Windows NT 4.0 or Windows NT Server 4.0, Terminal Server Edition. For additional information, please see the following article in the
Microsoft Knowledge Base:
Q152734 How to Obtain the Latest Windows NT 4.0 Service Pack
For your convenience, the English version of this post-SP3 hotfix has been
posted to the following Internet location. However, Microsoft recommends
that you install Windows NT 4.0 Service Pack 4 to correct this problem.
ftp://ftp.microsoft.com/bussys/winnt/winnt-public/fixes/usa/NT40/hotfixes-postSP3/prnt-fix/
STATUS
Microsoft has confirmed this to be a problem in Windows NT 4.0 and Windows NT Server 4.0, Terminal Server Edition. This problem was first corrected in Windows NT 4.0 Service Pack 4.0 and Windows NT Server 4.0, Terminal Server Edition Service Pack 4.
Additional query words:
lpt1 lpt2
Keywords : kbprint NT4SP4Fix kbbug4.00 ntprint kbfix4.00.sp4
Version : WinNT:4.0
Platform : winnt
Issue type : kbbug