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

Similar Messages

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 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 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?
>  
> 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.
>  
>
> 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

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!

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 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

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

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

Calling external dll from oracle 8i pl/sql

Hi
I am facing in calling extrenal dll from pl/sql.
Steps followed by me are
1.
create library crc_lib as
'D:\ORACLE\ORA81\RDBMS\EXTPROC\EXTPROC\my.DLL';
2.
CREATE OR REPLACE FUNCTION check_file_crc (f1 char)
RETURN BOOLEAN AS
EXTERNAL LIBRARY CRC_LIB
NAME "Check_File_CRC"
LANGUAGE C;
3. CREATE OR REPLACE PROCEDURE CRC_TEST (f1 varchar2) AS
     RetValue varchar2(100);
BEGIN
     if check_file_crc(f1) then
          RetValue := '0';
     else
          RetValue := '1';
     end if;
     DBMS_OUTPUT.PUT_LINE(RetValue);
EXCEPTION
     when others then
     DBMS_OUTPUT.PUT_LINE(sqlerrm|| 'I am in exception');
END;
4.ET SERVEROUTPUT ON
SQL> exec crc_test('C:\file.txt');
ORA-28576: lost RPC connection to external procedure agent
I am in exception
I have tsnames.ora as
EXTPROC_CONNECTION_DATA =
(DESCRIPTION =
(ADDRESS_LIST =
(ADDRESS = (PROTOCOL = IPC)(KEY = EXTPROC1))
(CONNECT_DATA =
(SID = PLSExtProc)
(PRESENTATION = RO)
and listner.ora as
SID_LIST_LISTENER =
(SID_LIST =
(SID_DESC =
(SID_NAME = PLSExtProc)
(ORACLE_HOME = D:\Oracle\ora81)
(PROGRAM = extproc)
I am unable to resolve problem please help.
Prashant
Edited by: prashant13 on Jul 23, 2009 11:27 AM

See if MOS note      468404.1 proves helpful here (though not meant for your version of Oracle).

Calling LV DLL from VB

I have a vi that initializes, measures, and releases
an OSA instrument. I want to call this routine from VB.
I used Standard calling convention when making DLL from LV.
Here is my VB declaration:
Private Declare Sub OSAMeasurement Lib "C:\ADE\OSAMeasurement.dll" Alias "OSADFBMeasurement" _
(ByVal GPIB As Long, _
ByVal Serial_Number As String, _
ByVal FileName As String, _
ByVal File_Path As String, _
ByVal Start_Wavelength_nm As Double, _
ByVal Stop_Wavelength_nm As Double, _
ByVal Level_Scale_dB As Double, _
ByVal Res_nm As Double, _
ByVal Peak_Wavelength As Double, _
ByVal Peak_Level As Double, _
ByVal SMSR As Double, _
ByVal FWHM As Double, _
ByVal Mode_Offset As Double, _
ByRef Level_Array() As Double, _
ByRef Wa
velength_Array() As Double, _
ByVal Array_Length As Long)
Here is my VB call:
Call OSAMeasurement(Form1.OSA.PrimaryAddress, _
(strOXM & Form1!txtOPMNumber), _
(CStr(CInt(dblSetVoltage)) & "v_Scan.txt"), _
(txtDataStoragePath & strOXM & " " & Form1!txtOPMNumber & "\"), _
1520, 1620, 5, 1, Peak_Wavelength, Peak_Level, _
SMSR, FWHM, Mode_Offset, _
Level_Array, Wavelength_Array, 1001)
I get RunTime Error "49"
Bad DLL calling convention
What is wrong?
Any suggestions/comments?
Attachments:
OSA.zip ‏703 KB

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

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 can I calling LabView DLL within LabView and pass similar Data Types?

I am trying to use an Instrument Driver, which is created in LabView6.1 as a DLL. At this point I have only LabView to test this DLL. I was wondering, is there easy way to find out what sort of Parameter or Data Type I should be using.
How can I pass the following data with in LabView:
LVRefnum as Type?
LVBoolean as Type?
TD1 (a structure) as Type?
It is funny to see that I am able to create a DLL in labview but having trouble calling it within LabView. I thought, it would be easier to test the DLL within the same environment.
Basically, I am more worried about the VISA calls that are used in the driver to communicate with instrument. Because, there is no link to �VISA32.dll� in
the header file, is that handled by the LV Run-time engine? I guess more details are needed on using the LabView DLL within LabView from National Instrument Technical Support.
Attachments:
RL5000.h ‏1 KB

A LVRefNum seems to be an unsigned long data type (32bit). You can cast it
in LV then use that as a parameter to call the DLL. (an Occurrence type
seems to be a Ulong32)
When you created the DLL what was the resulting type for the LVRefNum?
Happy Holidays
"Enrique" wrote in message
news:[email protected]..
> I see...
>
> After doing some research, it seems to me that there is no easy way to
> find out the type of data, other than looking at the header file and
> have documents like Using External Code in LabVIEW handy. The
> following information is from that document:
>
> LVBoolean is an 8-bit integer. 1 if TRUE, 0 if FALSE.
>
> LabVIEW specifies file refnums using t
he LVRefNum data type, the
> exact structure of which is private to the file manager. To pass
> references to open files into or out of a CIN, convert file refnums to
> file descriptors, and convert file descriptors to file refnums using
> the functions described in Chapter 6, Function Descriptions.
>
> I know you are creating a dll in LabVIEW, but I am pretty sure the
> information applies as well and is useful. For your dll this can be
> interpreted that, rather than passing a LVRefnum, try passing the file
> descriptor.
>
> From the header file, is can be deduced that TD1 is a cluster in
> LabVIEW.
>
> You are right in saying that "more details are needed on using the
> LabView DLL within LabView from National Instrument Technical
> Support.".
>
> Enrique

Calling C# dll from inside of JavaScript

I have a LabView application that uses javascript to call into some database stored procedures. I was wondering if there is a way of calling a .Net dll from inside of the Javascript without having to register the dll as a COM server. Are there any examples out there that I can take a look at?

That certainly seems like a roundabout way of doing things. Why do you need to use Javascript? Is this related to this question? If found this and this via Google.

Can't step into CVI step that calls LabVIEW DLL?

Windows 2000 SP1
TestStand 2.01f
LabWindows CVI 6.0
LabVIEW 6.1 Runtime
We have a framework based on TestStand and CVI. A customer has supplied us
with a DLL written in LabVIEW 6.1 and packaged with the Application Builder
that we need to call from a CVI test library DLL. They say they can't
supply us with a non-LabVIEW implementation. We installed the LabVIEW 6.1
run-time. We added code to the CVI test library to dynamically load and
unload the LabVIEW DLL using LoadLibrary and FreeLibrary. LoadLibrary is
called in a function in the MainSequence Startup step group, FreeLibrary is
called in a function in the MainSequence Cleanup step group.
Things run as expected when the CVI DLL is built as Release or Debug and the
CVI
adapter is configured to run in-process.
However, if we try to debug CVI DLL by building it as Debug and configuring
the CVI adapter to run in an external instance of CVI, things hang the first
time we try to step into, or run, a CVI test library step that calls one of
the functions in the LabVIEW DLL. On the Applications tab in Task Manager,
the item named LabVIEW is marked as 'Not Responding'. The only way to
recover is to kill the LabVIEW process, which takes down CVI and TestStand
with it. If none of the LabVIEW DLL functions are called, no problems are
seen (no hang).
I assume the problem has something to do with the library getting mapped to
the wrong process space (TestStand v. the external CVI instance). Is there
any way to solve this problem? Any ideas or suggestions would be
appreciated.
Joe

> Out of curiousity, what happens if you attempt to debug your DLL from
> CVI? For example, configure TestStand to run its steps 'inProcess'...
> but then close the TestStand application and in CVI, configure it so
> that the Specified External Process dialog points to TestStand's
> SeqEdit.exe (CVI launches TestStand when debugging the project). Once
> TestStand is running, run your test and set your break points as
> usual, you should be able to step into the CVI code if nothing else.
> If not, I would be interested in hearing what problems you encounter.
When 'debugging' SeqEdit from CVI, we experienced no lock up.
Thanks for this suggestion. Debugging from CVI is a workaround for now,
though not highly desirable as it is reverse from normal debug proc
edure
(user can't step into CVI from TestStand). Still would like to know if
'normal' debugging of this problem is possible.
> The nice thing about debugging directly from Labwindows/CVI while
> TestStand runs 'inprocess' is that you can avoid some library linking
> errors, which may be the source of the troubles you are seeing.
The problem appears to be general to LabVIEW DLLs called from an external
instance of CVI under TestStand. We were able to reproduce the problem with
a simple LabVIEW VI compiled to a DLL, then called from a simple CVI DLL
under TestStand. We will package up some sample code and submit it to NI
tonight or tomorrow.
Thanks for you help.
Joe

Calling LabView DLLs from C/C++

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