Access ni4882.dll with Qt and MinGW

Question

I have to control some electric loads and power supplies over GPIB. We use Qt 4.7.4 with MinGW 4.4 (32-bit) on Windows 7 64-bit.
The packet NI-488.2 GPIB Drivers packet 3.0.2 for Windows 7 64-bit is installed. The GPIB Troubleshooting Utility tool shows "pass" and the Measurement & Automation application can connect to the board and talk to an intrument. So far so good.
Now I want to write an application to use the NI4882.dll (3.0.0.49153). Unfortunately, there are just object files for Microsoft and Borland compilers and no lib file.
So we generate a def file from the ni4882.dll with:
pexports -h ni4882.h ni4882.dll > ni4882.def
-ni4882.def-
LIBRARY NI4882.dll
EXPORTS
?compareVersion@nGPIBAPI_NI4882@@YGXABVtSSVersion@@0AAJPBD@Z
?getCurrentVersion@nGPIBAPI_NI4882@@YG?AVtSSVersion@@AAJ@Z
?getOldestCompatibleVersion@nGPIBAPI_NI4882@@YG?AVtSSVersion@@AAJ@Z
AllSpoll@12
DevClear@8
DevClearList@8
Then generate the lib with:
dlltool -k -D ni4882.dll -d ni4882.def -l libni4882.a
Now, I've build a small test program in Qt.
-.pro file-
INCLUDEPATH += $$PWD/include
LIBS += $$PWD/lib/libni4882.a
-.cpp file-
#include "ni4882.h"
void MainWindow::Init()
  int dd = idev(0,3,0,T10s,1,0);
  if(Ibsta()&ERR)
    Err(tr("Unable to open board:ibdev=%1").arg(dd));
  if( ibonl(0,0)&ERR)
    Err(tr("Unable to close board"));
void MainWindow::Err(QString message)
  switch(Iberr())
    case 0:
      message.append("(EDVR - System error)");
    } break;
  qDebug("Error : %s\nibsta = 0x%x iberr = %d\n",
    (unsigned int)Ibsta(), (int)Iberr());
The source code will be compiled and linked without an error.
But if I run it, the output is:
Error : Unable to open board: ibdev=32768 (EDVR - System error)
ibsta = 0x8000 iberr = 0
Error : Unable to close board (EDVR - System error)
ibsta = 0x8000 iberr = 0
So, the question is: What is wrong? Why do I always receive this EDVR error. I also tried SendIFC(0) with the same result.
With the GPIB Interactive Control tool, I can communicate with my instrument and the NI I/O Trace logs it. But I can't see logs in the Trace tool from my application. Is this an indication?
Any ideas?
Marko
Solved!
Go to Solution.

Answer 1

Hi to all,
after some questions about using the GPIB library with Qt, I've written a step by step description to create object files for MinGW:
1. Create a folder and copy the "gpib-32.dll" from the "C:\Windows\System32" ("C:\Windows\SysWOW64" in Win7) to this folder.
2. Copy "ni488.h" from "c:\Program Files (x86)\National Instruments\Shared\ExternalCompilerSupport\C\include\". (Not ni4882.h!)
3. Load PExports (my version is 0.44) and put the exe in your folder to. I do not have a URL to load this tool but should be easy to find. It's freeware.
4. Copy dlltool.exe from "c:\QtSDK\mingw\bin\" to your folder.
5. Create a batch file "1 - build def file.bat" with the content: "pexports -h ni488.h gpib-32.dll > gpib.def"
6. Create a batch file "2 - build lib file.bat" with the content: "dlltool -k -D gpib-32.dll -d gpib.def -l libgpib.a"
7. Start the batch file "1 - build def file.bat" to create the def file "gpib.def"
8. Start the batch file "2 - build lib file.bat" to create the library file "libgpib.a"
9. Copy "gpib-32.dll" and "libgpib.a" to your software project. I created the subfolder "lib" and copied the files into.
10. Copy "ni488.h" to your software project. I created the subfolder "include" and copied the file into.
11. Into your PRO file type:
# Include the NI 488.2 library
INCLUDEPATH += $$PWD/include
HEADERS += include/ni488.h
LIBS += $$PWD/lib/libgpib.a
12. In your source code type:
#include "windows.h"
#include "ni488.h"
bool InitializeGPIBBoard( )
bool isStarting = false;
int boardID;        /** @brief Board id. */
QString boardName;  /** @brief Board name. */
int boardDescr;     /** @brief Board descriptor. */
// Get board ID
SendIFC(boardID);
if( ThreadIbsta() & ERR )
    ErrorHandling(tr("Unable to open board"));
    return isStarting;
// Open and initialize a board or a user-configured device descriptor
wchar_t *aName = new wchar_t[boardName.size()+1];
m_para.boardName.toWCharArray( aName );
aName[boardName.size()] = 0;
m_para.boardDescr = ibfind( aName );
delete []aName;
// The board is the System Controller.
if( ibconfig( boardDescr, IbcSC, 1 ) & ERR )
    ErrorHandling(tr("Unable to set the board to System Controller"));
    return isStarting;
// Assert interface clear.
if( ibsic( boardDescr ) & ERR )
    ErrorHandling(tr("Assert interface clear"));
    return isStarting;
// aso.
isStarted = true;
return isStarted;
13. Be happy! :-)
I hope that helps. If you have problems, please write me a message or post on this board thread.
Gruß und viel Erfolg!
Marko