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write a byte to the parallel port under NT4.0?

Posted on 1997-05-02
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Last Modified: 2013-12-04
I tried to write a byte to the parallel port in this way:

      HANDLE hLPT;
      DWORD nNumberOfBytesWritten;
      BYTE  ccb;
      BOOL bWriteFile,bCloseHandle, bWait=FALSE, bOVResult;
      OVERLAPPED st_Overlapped;
      ccb=1;

      hLPT=CreateFile("LPT1",GENERIC_READ|GENERIC_WRITE,0,NULL,OPEN_EXISTING,FILE_FLAG_OVERLAPPED,NULL);
      bWriteFile=WriteFile(hLPT, &ccb, 1, &nNumberOfBytesWritten, &st_Overlapped);
      bCloseHandle=CloseHandle(hLPT);      

This works only if I have installed a printer driver to lpt1! Then, after proceeding, a print message window opens and tells me there is no paper in the printer, but I will not print!!!
I need a solution with about 10 or 20  rows, not a complicated VxD driver or something.
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Question by:nil_dib
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gysbert1 earned 100 total points
ID: 1397072
I'm afraid you'll have to use a "complicated VxD" You're trying to access the printer port through the printer driver. It looks at the status lines on the port, and detects a paper out error. What you need is driver that allows arbitrary access to the port.

I know you're not using Delphi, but try this anyway:

Go to the Delphi superpage (sunsite.icm.edu.pl), click on search and type "port hardware" and click the 32 bit checkbox. The first result is a delphi component to allow arbitrary port access. It includes a VxD, which allows arbitrary port access. You should be able to use this VxD with your program as well...
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