How to call Labview DLL from VB2005

Dear all expert,
I'm a student and very new in Labview programming.
Currently i have build a simple vi and need to convert it to dll so that i can call it from my VB.net. But the problem is how to call the labview dll from my VB.net?
I know we must declare function something like this,
Auto function Bodeplot Lib"..\\Bodeplot.dll" (Byval Val1 as double, Byval Val2 as double,...) as double
but how to determine Val1, Val2 (and so on) is input for which data?  if my vi have 10 input (frequency, Kc,Fcz,Fcp,Wzrhp,Wp,k,Wz,Beta and Operation) ? and how to select the output (my application have 3 possible output : magnitup loop,phase loop, and degree loop)
In addition, since I'm using Labview 8.0 , and as i know apllication  builder for this version cannot convert vi to dll which contain Mathscript (but unfortunely, my vi all use Mathscript), so really hope someone can help me to convert my vi to dll using Labview 8.2 (which remove this limitation).
here I'm attach my Vi and really hope someone willing to help.
Thank you.
Attachments:
bodeplot.vi ‏1049 KB

On Sep 17, 6:40 am, cckoh <[email protected]> wrote:
> Dear all expert,
> I'm a student and very new in Labview programming.
> Currently i have build a simple vi and need to convert it to dll so that i can call it from my VB.net. But the problem is how to call the labview dll from my VB.net?
> &nbsp;
> I know we must declare function something like this,
> &nbsp;
> Auto function Bodeplot Lib"..\\Bodeplot.dll" (Byval Val1 as double, Byval Val2 as double,...) as double
> &nbsp;
> but how&nbsp;to determine Val1, Val2 (and so on) is input for which data?&nbsp; if my&nbsp;vi have&nbsp;10 input (frequency, Kc,Fcz,Fcp,Wzrhp,Wp,k,Wz,Beta and Operation)&nbsp;? and how to&nbsp;select the output (my application have 3 possible output : magnitup loop,phase loop, and degree loop)
> &nbsp;
> In addition, since I'm using Labview 8.0 , and as i know apllication&nbsp; builder for this version cannot convert vi to dll which contain Mathscript (but unfortunely, my vi all use Mathscript), so really hope someone can help me to convert my vi to dll using Labview 8.2 (which&nbsp;remove this limitation).
> &nbsp;
> here I'm attach my Vi and really hope someone willing to help.
> &nbsp;
> Thank you.
> &nbsp;
>
> bodeplot.vi:http://forums.ni.com/attachments/ni/170/272124/1/bodeplot.vi
If you insist on using Labview with your project then you should
consider using ActveX in place of using a dynamic link library to
interface to your VB.net code. You don't need "Application Builder"
if you use ActiveX. The Student, Basic and Full development versions
of Labview for Windows come with ActiveX capability. For more
information on ActiveX look up the subject ActiveX in Labview's Help
File.
Howard

Similar Messages

  • How to call LabVIEW dll from ATL COM dll

    I have tried to call simple LabVIEW 8.6 Dll from win32 test application, class Library.
    I have include LabVIEW generated SharedLib.h file and SharedLib.lib file in the test application which I created as simple win32 console project and also from win32 class Library. I was sucessfully able to call my LabVIEW dll funtion. 
    But when I create ATL COM project and try to add SharedLib.h file and SharedLib.lib file I used to get following erors
    Error 1 error C2733: second C linkage of overloaded function 'StrCatW' not allowed d:\program files\national instruments\labview 8.6\cintools\extcode.h 463 
    Error 2 error C2733: second C linkage of overloaded function 'StrCpyW' not allowed d:\program files\national instruments\labview 8.6\cintools\extcode.h 464 
    Error 3 error C2733: second C linkage of overloaded function 'StrCpyNW' not allowed d:\program files\national instruments\labview 8.6\cintools\extcode.h 465 
    Error 4 error C2733: second C linkage of overloaded function 'StrCmpW' not allowed d:\program files\national instruments\labview 8.6\cintools\extcode.h 466 
    Error 5 error C2733: second C linkage of overloaded function 'StrCmpNW' not allowed d:\program files\national instruments\labview 8.6\cintools\extcode.h 467 
    these many errors.
    Will some one explain me how to call LabVIEW dll from ATL COM dll.
    Thanks & Regards,
    Jay

    I also had this problem.  My application is unicode-aware, but I was attempting to link it to a library with primitive C-string arguments.  You could dynamically load the DLL as suggested (more work), modify the header files (really not recommended), or if you are feeling lucky you could try fooling the compiler, as I was successfully able to do in Visual Studio 2010, by steering the preprocessor around those functions (assuming you're not using them, of course -- otherwise this probably wouldn't work):
    // prepare for NI extcode.h inclusion. avoid linker errors for this project.
    #define StrCatW(a,b)     IgnoreLinkError_StrCatW(a,b);
    #define StrCpyW(a,b)     IgnoreLinkError_StrCpyW(a,b);
    #define StrCpyNW(a,b,c)  IgnoreLinkError_StrCpyNW(a,b,c);
    #define StrCmpW(a,b)     IgnoreLinkError_StrCmpW(a,b);
    #define StrCmpNW(a,b,c)  IgnoreLinkError_StrCmpNW(a,b,c);
    // header file for my LabView-built DLL (ASCII single-byte character arguments)
    #include <MyLibraryHeader.h>
    // clean up afterwards, put things back to 'normal'
    #undef StrCatW
    #undef StrCpyW
    #undef StrCpyNW
    #undef StrCmpW
    #undef StrCmpNW

  • How to call labview DLL from C#, passing char, char[], float[], long, short

    Hi,
    I'm having trouble calling labview dll from C# to perform certain function.
    The function supposed to return the values in the float Analysis[] array. However, when I execute it it only returns zero values.
    It seems that some parameters are not properly passed to the dll.
    Below is the function in the header file:
    void __stdcall Optical_Center(char FileDirectory[], long ImagePtr,
        short int Height, short int Width, char ReadFromFile, float Analysis[],
        long lenAnalysis);
    and my corresponding dll import in c#:
    [DllImport(@"SMIA.dll", CharSet = CharSet.Ansi)]
            public static extern void Optical_Center([MarshalAs(UnmanagedType.LPStr)]string FileDirectory, long ImagePtr,
                short Height, short Width,char  ReadFromFile, IntPtr Analysis,
                long lenAnalysis);
    string str = @"C:\SMIA.raw";
    int len = 3;
    long m_lenAnalysis = 3;
    long m_ImagePtr = 0;
    short m_Height = 2464;
    short m_Width = 3280;
    IntPtr m_PtrArray = Marshal.AllocHGlobal(len * Marshal.SizeOf(typeof(float)));
    char m_ReadFromFile = '1';
    Optical_Center(str,m_ImagePtr,m_Height,m_Width,m_ReadFromFile,m_PtrArray,m_lenAnalysis);
    float[] m_Analysis = new float[len];
    Marshal.Copy(m_PtrArray, floatArray,0,len);
    Marshal.FreeHGlobal(m_PtrArray);
    string printstr = "";
    for (int i=0; i<len; i++)
        printstr = printstr + floatArray[i].ToString() + "\n";       
    MessageBox.Show(printstr);
    Appreciate if anyone can help, thanks.
    KL

    I was just about to post the header file of the DLL, when
    I noticed that there's a function called LVDLLStatus.
    This little thingie turned out to be a rather handy tool.
    With that function I found that in the DLL I had a problem
    with another function that prevented the DLL to be correctly
    loaded.
    This other function in the DLL is for generating digital output
    and it worked as it should, when tested from LV.
    Anyway if someone is interested, I got it working by using
    the LoadLibrary and GetProcAddress function, as in the
    source code thatI posted earlier.
    I will investigate what is wrong with that digital output, and
    post into a another thread if I have problems with that.

  • How to call labview DLL from visual C++?

    Hi,
    I'm trying to call a LV DLL from a VC++ application
    by using the LoadLibrary and GetProcAddress functions.
    The DLL contains a simple sum function. The Library is
    loaded correctly, but the result is always 0.0000.
    I have loaded a VC++ DLL in a similar way and it works
    correctly. Also, I have tested the DLL by loading it in LV,
    and it works correctly. The calling convention is defined
    to be stdcall in LV Application Builder.
    I have also tried this solution, but I will get a compiler error
    from one the header files that are created by the LV when
    the DLL is made. The error comes from this line
    typedef char                int8;
    and the error states that
    ..\fundtypes.h(107) : error C2371: 'int8' : redefinition; different basic types
    If someone knows of newer tutorial(for LV 8.2) or knows how to use those
    LoadLibrary and GetProcAddress function for LV DLLs, I will appreciate the
    information greatly.
    Below is the code that I'm using for loading the LV DLL.
    Thanks
    #include "stdafx.h"
    #include <stdio.h>
    #include <stdlib.h>
    #include <map>
    #include <windows.h>
    int _tmain(int argc, _TCHAR* argv[])
        HINSTANCE LVLib = LoadLibrary(TEXT("Testdll"));
        typedef double (__stdcall *MYPROC)(double, double);
        if (LVLib != NULL)
            MYPROC ProcAdd = (MYPROC) GetProcAddress(LVLib, "Add");
            if (ProcAdd != NULL)
                double d = (ProcAdd)(5.5, 6.6);
                printf("sum = %f\n", d);
            else
                printf("Invalid function pointer\n");
        else
            printf("Failed to load the library\n");
        return 0;

    I was just about to post the header file of the DLL, when
    I noticed that there's a function called LVDLLStatus.
    This little thingie turned out to be a rather handy tool.
    With that function I found that in the DLL I had a problem
    with another function that prevented the DLL to be correctly
    loaded.
    This other function in the DLL is for generating digital output
    and it worked as it should, when tested from LV.
    Anyway if someone is interested, I got it working by using
    the LoadLibrary and GetProcAddress function, as in the
    source code thatI posted earlier.
    I will investigate what is wrong with that digital output, and
    post into a another thread if I have problems with that.

  • Calling LabView DLLs from C/C++

    Hi!
    Is it possible to call functions in the LabView DLLs directly from
    C/C++?
    Functions like InvChiSquare in lvanlys.dll has "Adapt to Type" void *
    parameters. How do I specify those parameters from C/C++?
    I have tried to use the "Build Shared Library" function in LabView to
    make a wrapper dll of the "Inv Chi Square Distrubution" vi, but when I
    call this function in the dll from C/C++ the function never returns.
    Other functions in the same dll that does not use functions in the
    lvanalys.dll are working ok.
    Regards
    Hans Forssell

    There are 2 great places to get infomraiton on passing data to dlls, and the data types used. First would be this manual. Using External Code in LabVIEW
    The second is the dll examples that ship with LabVIEW 7.0. Go to LabVIEW 7.0\examples\dll\data passing\Call Native Code.vi

  • Calling LabVIEW DLL from C with 2d array strings

    I am trying to write a DLL in C that calls a LabVIEW DLL that has a
    number of functions that each return a 2D array of strings which are the formatted
    measurements, with column 1 being the measurement name and column 2
    being the measurement. I wanted to use the 2D array of strings since
    this would give a uniform interface for returning measurements. Ive
    cobbled together bits and pieces of messages and example code I've
    found here into something that almost works, and was hoping someone
    with a little more experience in interfacing C with LabVIEW DLLs would
    be able to help me.
    Here's a little
    snippet from the header file generated when building the LabVIEW DLL:
    typedef struct {
    long dimSizes[2];
    LStrHandle String[1];
    } TD1;
    typedef TD1 **TD1Hdl;
    long __cdecl TestVI(char serialNumber[],  TD1Hdl *formattedMeasurements, char ErrorDescription[], long len);
    The "TestVI" VI generates a 2D array of strings. The cell contents and number of rows are random to
    simulate different measurement names and measurements.
    Here's a snippet for the wrapper class:
    class CArgoTestsLabVIEW 
    public:
    CArgoTestsLabVIEW();
    virtual ~CArgoTestsLabVIEW();
    // test modules called from parent DLL
    BOOL GetResult_LV(CString resultName, double *result);
    long TestVI_LV(CString serialNumber);
    private:
    TD1Hdl m_LVStringArray;
    CMapStringToString m_resultMap;
    InitMeasurementsArray();
    PopulateResultMap();
    The "m_LVStringArray" is intended to hold the 2D array of strings that
    the test modules spit out. The "m_resultMap" is just for accessing the
    measurements from the parent DLL via the "GetResult_LV" function.
    The implementation of TestVI_LV is:
    long CArgoTestsLabVIEW::TestVI_LV(CString serialNumber)
    long rc = 0;
    char errStr[BUFFERLEN];
    strcpy(errStr,"");
    rc = InitMeasurementsArray();
    if (rc == 0) {
    rc = TestVI(serialNumber.GetBuffer(serialNumber.GetLength()), &m_LVStringArray, errStr, BUFFERLEN);
    PopulateResultMap();
    return rc;
    The accessor functions InitMeasurementsArray and PopulateResultMap are:
    long CArgoTestsLabVIEW::InitMeasurementsArray()
    MgErr err;
    if (m_LVStringArray)
    DSDisposeHandle(m_LVStringArray);
    m_LVStringArray = (TD1Hdl)DSNewHandle(sizeof(TD1));
    // code to check for NULL
    // Set number of strings in array to 0
    (*m_LVStringArray)->dimSizes[0] = 0;
    (*m_LVStringArray)->dimSizes[1] = 0;
    // Set total size of array structure. For now it is only as big as the long variable.
    err = DSSetHandleSize((UHandle)m_LVStringArray, sizeof(long));
    // code to check for error
    return 0;
    void CArgoTestsLabVIEW::PopulateResultMap()
    int numberOfResults;
    int i;
    int charCnt;
    numberOfResults = (*m_LVStringArray)->dimSizes[0];
    if (numberOfResults == 0) {
    return;
    m_resultMap.RemoveAll();
    for (i = 0; i < numberOfResults; i++) {
    charCnt = (*((*m_LVStringArray)->String[i * 2]))->cnt;
    (*((*m_LVStringArray)->String[i * 2]))->str[charCnt] = '\0';
    charCnt = (*((*m_LVStringArray)->String[i * 2 + 1]))->cnt;
    (*((*m_LVStringArray)->String[i * 2 + 1]))->str[charCnt] = '\0';
    m_resultMap.SetAt((LPCTSTR) (*((*m_LVStringArray)->String[i * 2]))->str, (LPCTSTR) (*((*m_LVStringArray)->String[i * 2 + 1]))->str);
    The problem I have is that I eventually get an access violation from
    the run-time engine if I try to call the test VI in a loop. I'm
    obviously having a memory management problem, but it escapes me as to
    where the problem is. Anybody have any ideas?

    smercurio_fc wrote:
    The problem I have is that I eventually get an access violation from the run-time engine if I try to call the test VI in a loop. I'm obviously having a memory management problem, but it escapes me as to where the problem is. Anybody have any ideas?
    (*((*m_LVStringArray)->String[i * 2]))->str[charCnt] = '\0';
    Hi smercurio,
          Have you solved this?  I don't work with C much anymore, but it looks, here, as if the memory at str[charCnt] isn't yours to address/change.
    Is index "charCnt" one char past the end of the String-memory allocated by LabVIEW? 
    just an idea!
    Hmmm, maybe page 9 is a bit far back to fish in the unanswered posts.
    Message Edited by Dynamik on 03-03-2006 02:03 AM
    When they give imbeciles handicap-parking, I won't have so far to walk!

  • Error while caling Labview DLL from VB2005

    Dear all expert,
    i'm a student and very new in Labview. Currently, i design a application using Labview8.2 and need convert it to dll. So that i can call it fom my VB2005.
    I'm encounter an error, there is my computer "hang" when calling the labview dll. I suspect this may due unproper way i calling the labview dll in my VB program. So, really hope some one can give me any suggestion and modification to my program. I attach my vi and Vb program.
    for your information,
    i already install labview run time engine 8.2.1 and uncheck the "Loader Lock detected".
    below is the Function Prototype create when i using Application Builder to build the dll.
    void Bodeplot(unsigned short Operation, double Beta, double Frequency, double Kc, double Fcz, double Fcp, double Wz, double Wp, double Wzrhp, double k, double *Output)
    Thank you very much.
    Attachments:
    MyProgram.zip ‏723 KB

    Hi cckoh,
    A couple suggestions include:
    1) Make sure you are using the correct .NET data types that map to the data type that LabVIEW uses. For example, your Operation paramter for your DLL is an unsigned short which is equivalent to a System.UInt16 in .NET.
    2) You should be using ByRef instead of ByVal for your output parameters. For example, in your function prototye, you have double *Output. For example, when you import your unamanged DLL, the prototype you should use woudl be:
    Declare Auto Function Bodeplot Lib "........."(ByVal Operation as System.UInt16, ........ ByRef Output as Double)
    I tested this out and it loads the DLL, calls the function, and returns without problems.
    Hope this helps!!
    Best Regards,
    Jonathan N.
    National Instruments

  • Calling LabView dlls from VB

    I am using the .net environment and this NI e xample...
    http://zone.ni.com/devzone/cda/epd/p/id/3990
    which is just a simple dll that outputs some numbers.
    I get the following error
    Attempting managed execution inside OS Loader lock. Do not attempt to
    run managed code inside a DllMain or image initialization function
    since doing so can cause the application to hang.
    and it crashes! Any suggestions?

    This issue is addressed in the forum linked by Ravens Fan.
    Donovan

  • Calling a dll from VB

    Hi all
    I have two questions
    1) I know about the visual Basic 6 but what is measurement studio for visual Basic 6?
    2) Can anyone tell me how to call a dll from Visual Basic 6? Any example for this ?
    Any help greatly appreciated :-)

    Basically what i want to do is to call the microchip's dll called "mpusbapi.dll" from VB6. This dll is written in C++. This dll has some basic functions of usb like MPUSBRead() , MPUSBWrite , MPUSBOpen() etc.
    I have made a usb data acquisition card and i want to communicate with this card by means of VB 6. Please tell me or send a tutorial of calling a DLL from VB 6.
    Any help greatly appreciated
    Attachments:
    _mpusbapi.cpp ‏42 KB
    _mpusbapi.h ‏19 KB

  • How to call a labview dll from excel-VBA?

    How to call a simple Labview DLL from Excel VBA?
    I have seen examples of DLL calls from VB but does it work the same way for VBA? I have 2000 excel and Labview 8.5. I created the DLL and tried to call it from VBA using the same type of code as in NI's website example(ofcourse its a bit diff with 8.5)
    http://zone.ni.com/devzone/cda/tut/p/id/...
    BUT it errors out when called from excel
    ERROR: The object invoked has disconnected from its client

    You would need to provide more details about the LabVIEW DLL, such as the prototypes of the functions (VIs) that you're trying to call, and your actual VBA code. Specifically, what object you're trying to create. You should also make sure the Run-Time Enginer is installed, as well as any required libraries such as the VISA Run-Time if you're using VISA. Have you made sure to enable the ActiveX server for the DLL?
    A search yielded the following items that you may wish to peruse:
    http://forums.ni.com/ni/board/message?board.id=170&message.id=261345&requireLogin=False
    http://forums.ni.com/ni/board/message?board.id=170&message.id=45099&requireLogin=False
    http://forums.ni.com/ni/board/message?board.id=170&message.id=299209&requireLogin=False
    http://forums.ni.com/ni/board/message?board.id=170&message.id=195846&requireLogin=False

  • How to call LabVIEW ActiveX dlls into VB6

    I'm jumping in on a project written primarily in VB6. I'd much rather wirte code in LabVIEW so what I am looking for is some example code for calling LabVIEW activeX dlls into VB6. Does anyone have example code? I need to see how the LabVIEW libraries and classes are called and used in VB6.

    Hi Drewdafis,
    Refer to this link for example code on calling a LabVIEW DLL from Visual Basic.
    Hope this helps!
    Best Regards,
    Jonathan N.
    National Instruments

  • How to call the DLL writing in Vb6.0 from testsatnd?

    Hi,
    I want to call a dll writting in VB6.0 from teststand. But as i see from the "Step Setting" in teststand, only the C/C++ Dll can be selected in the "adapter" type. I try to use this one as my adapter to call my VB6.0 dll, in result, there is no function can be seen in the "function" tab in teststand.Anyone know how to call the DLL writing in Vb6.0?
    Solved!
    Go to Solution.

    Hi Ivan,
    Just to be sure that your DLL is not wrong
    you have check if all functions are well and present.
    There is  tool called "Dependency Walker"   You can download it at http://dependencywalker.com/ .
    With it you can look "inside" your dll
    If you will see your functions there, you will see them (in my case !!always!!) in TestStand, too.
    Hope this helps 
    Greetings
    Juergen
    =s=i=g=n=a=t=u=r=e= Click on the Star and see what happens :-) =s=i=g=n=a=t=u=r=e=

  • How to call LabVIEW from TestDirector

    Hai to all,
    I want to call LabVIEW function from TestDirector. That TestDirector using VBScript. is it posible? if posible can you give the procedure.
    thanks for advance!
    reddy

    Hello,
    in this case you have to contact Mercury for more informations. There are no experiences in this way from the LV side.
    Regards
    Thomas D.
    NI Germany
    (SRQ 204139)

  • Call LabVIEW VIs from MATLAB

    Does anybody know of a simple way to call LabVIEW VIs from within a MATLAB m-file?  I would like to be able to write VIs in LabVIEW and then script them (for stochastic analysis, etc.), and think MATLAB would be an awfully convenient way to do this (also useful for data analysis, etc.).  I have looked at LuaVIEW, but it appears to have been largely abandoned.
    Thanks!

    Hello Erik,
    Building it into a DLL as Altenback said is a solid way to do this, and here's a Knowledge Base article that also explains how to transfer data in binary or ASCII format, How do I Transfer Data Between The MathWorks, Inc. MATLAB® Software Development Environment and LabV... 
    Thank you,
    Deborah Y.
    LabVIEW Real-Time Product Marketing Manager
    Certified LabVIEW Architect
    National Instruments

  • How to call a dll which has one VISA name as input

    Hi there,
    The Labview application builder can generate a dll file from a vi which is a simple serial comunication program using VISA name as one control.
    The problem is how to call the dll file in Labview which has a VISA name as INPUT?
    Thanks!
    George

    I would suggest modifying the LabVIEW VI so that the input is a string control instead of a visa control. The LabVIEW application will work the same and there is no need for any casting. All visa VIs can take a string as an input. Then when you recreate the dll make the input a string. Then you can easily pass a string to the dll from any API.
    -Josh

Maybe you are looking for

  • Error message when attempting to export master file?

    I am running Mavericks and have FCP 10.1 When I try to export a master file, I keep receiving the error message "The share operation master file has failed.  An error occurred when creating frame ..... (error -1)." I've turned off background renderin

  • How do you have things organized in iPhoto?

    I'm in the process of organizing everything on my PowerBook. Currently I only use iPhoto for pictures that I want sync'd to my iPod. I really don't want to put all my photos in iPhoto, but I'm not sure. I'd like to hear how you guys use iPhoto. Do yo

  • Changed itunes library to new laptop - wont open!

    Having recently moved home and purchasing a new laptop i have downloaded itunes to my new laptop and copied my library from my old laptop to my external hard drive. after installing itunes on my new laptop i copied the library to the itunes folder in

  • Why can't Premiere Pro CC start?

    It never moves past the loading screen and just crashes. It's run flawlessly in the past, just this night it's being difficult. I've tried rebooting Creative Cloud by logging in and out - and of course the PC. I've also tried running it in compabilit

  • Deleting files on Time Machine HDD

    I have a folder containing 2GB or more of music that I don't need backed up any longer. How can I free up the space on my Time Machine HDD and delete this folder? Does Time Machine just reference this folder once or does it continuously make back ups