# LPT or COM redirected to USB Printer Port



## Peohguy (Oct 23, 2011)

*LPT or COM redirected to USB Printer Port*

*When redirecting a printer port from a MS-DOS based program to a USB printer should you only redirect the COM ports, COM1 or COM2 rather than the LPT ports, LPT1 or LPT2, since the COM ports are serial ports and the USB port is a serial port (Universal Serial Bus)? Such as explained in the following article:*

*How to print to a network printer from an MS-DOS-based program in Windows XP*

*Where the user can apply the DOS net use Command*

*Such as: net use lptx \\computername\printername /persistent:yes*

*More details on web site:*

http://support.microsoft.com/kb/314499 

The reason I ask is because as soon as I did a redirection to LPT2 and tried it out from my Generic Cadd 6 program my printer outputted a blank sheet of paper and I immediately received a Printhead error on my USB printer and I eventually had to replace it. Lexmark sent me a new printhead free of charge overnight delivery as soon as they understood that the problem was irresolvable within a couple of email days, my printer was only 2 weeks old at the time.
I am now reluctant to try it again until Im sure. Or do you think the printhead failure I experienced just a coincidence in timing and that would have happened anyway? The printer did have a few glitches in its output, e.g., several partial white outs of letters to words and some partial whiteouts of vertical lines at the right hand margin of a drawing from a Windows based drawing program. Incidentally the printout from my printer using the new printhead is now exceptionally sharp, clear, with no partial whiteouts of letters or words. 
If there is a problem with directing a Parallel DOS port to a USB printer, then is there a way I can undo the net use command that I executed?

Tech Support Guy System Info Utility version 1.0.0.2
OS Version: Microsoft Windows XP Professional, Service Pack 3, 32 bit
Processor: Intel(R) Celeron(R) D CPU 3.20GHz, x86 Family 15 Model 6 Stepping 4
Processor Count: 1
RAM: 1014 Mb
Graphics Card: Intel(R) 946GZ Express Chipset Family, 224 Mb
Hard Drives: C: Total - 63350 MB, Free - 14460 MB; D: Total - 10179 MB, Free - 1681 MB;
Motherboard: Acer, E946GZ
Antivirus: avast! Antivirus, Updated: Yes, On-Demand Scanner: Enabled

Thanks for any help
Peohguy


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## Snagglegaster (Sep 12, 2006)

Peohguy, the net use command doesn't care about the physical interface of the printer you want to use, and there is no way it could ever damage a printer. So, the first thing I would suggest would be deleting the current net use printer redirection by using the /delete switch. See http://technet.microsoft.com/en-us/library/bb490717.aspx for details. To remove the current redirection, you have to open a command prompt, and type the "net use" command followed by the same string you used to enable printer redirection except that you will replace the "/persistent:yes" switch with "/delete" (no quotations) and that will remove the current port redirection.

Next, make sure that your printer is a shared device and give it a short and simple share name like "lex". Now double check your program and see which printer port it prefers to use. A lot of old DOS software only prints to LPT1, though some can handle LPT2 as well. Anyway, set the program's output to the appropriate port and exit the program. Then open a command prompt and type "net use lptX \\computername\printersharename /persistent:yes" substituting the appropriate device names and omitting the quotation marks. Hit the enter key. If you typed the command correctly, you should get a confirmation and you are good to go. The same method works for printers connected via hardware print servers and virtual print servers; not just USB ports.


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## Peohguy (Oct 23, 2011)

Snagglegaster,
Thanks a lot for the information. I was hoping that was the case, but it's always great to have an expert allay my concerns (say fears). 
Since as you stated there is no way for net use to screw up my printer I see no need to change my redirection of LPT2 to my Lexmark. My DOS program gives me the choice to select either COM1, COM2, LPT1, LPT2, LPT3, or File.
I do really appreciate you directing me to the other web site on Net use. And I really appreciate your example regarding how to delete, which really clarifies the sometimes otherwise esoteric DOS syntax rules and explanations that sometimes really leave me up in the air.
I wanted to reply first B4 I retried it. I will let you know how it works out.

Best regards and again thanks for your help,
Peohguy


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## Peohguy (Oct 23, 2011)

Snagglegaster,
Im back.
I tried to print out my drawing from Generic Cadd redirected from LPT2 to my Lexmark, without changing anything from my previous net use lpt2 command. My printer spit out a single blank sheet of paper, then my Lexmark Pop up came on in effect saying that it was printing Local Downlevel Document with a stalled print progress bar, hadnt moved in 15 minutes. So I cancelled the print and went to my DOS command program and tried to delete lpt2 and kept getting error messages. I gave up and then did a net use to redirect to com1 then com 2 but got messages that the resources or connections were not available. I then tried did a net use to lpt1 and tried to print from my Generic Cadd program again and received the message that my printer was not communicating with my printer.
I finally had to reboot and start over again. I went back to DOS command prompt and did a net use for lpt2 and got a message that I completed the command successfully I then copied the dos window to ms word then changed the last part from /persistent:yes to /delete and copied and pasted that to my dos command window and still got error message on wrong switches, copied below for you to see what I am doing wrong: (italics and blue print to differentiate DOS window words if it comes through on my reply):

_C:\>net use lpt2 \\acer-6e395d0925\LexmarkP /persistent:yes_
_The command completed successfully._

_C:\>net use lpt2 \\acer-6e395d0925\LexmarkP /delete_
_A command was used with conflicting switches._

_More help is available by typing NET HELPMSG 3510._
_._
I havent been able to delete either lpt1 or lpt2.

My net use resources while my printer is idle as shown on my DOS screen 
(italics and blue print to differentiate DOS window words if it comes through on my reply):

_net use lpt2 \\acer-6e395d0925\LexmarkP /persistent:yes_
_Microsoft Windows XP [Version 5.1.2600]_
_(C) Copyright 1985-2001 Microsoft Corp._

_C:\>net use lpt2_
_Local name LPT2_
_Remote name \\acer-6e395d0925\LexmarkP_
_Resource type Print_
_Status OK_
_# Opens 0_
_# Connections 2_
_The command completed successfully._

_C:\>net use lpt1_
_Local name LPT1_
_Remote name \\acer-6e395d0925\LexmarkP_
_Resource type Print_
_Status OK_
_# Opens 0_
_# Connections 2_
_The command completed successfully._

These below after I initiated the print out from my my DOS program Generic Command (again, italics and blue print to differentiate DOS window words if it comes through on my reply):

_C:\>net use_
_New connections will be remembered._

_Status Local Remote Network_

_----------------------------------------------------------------------------_
_OK LPT1 \\acer-6e395d0925\LexmarkP_
_Microsoft Windows Network_
_OK LPT2 \\acer-6e395d0925\LexmarkP_
_Microsoft Windows Network_
_The command completed successfully._

Best regards,
Peohguy


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