Creating dll from Labview for use in VB

In this document:
Accessing LabVIEW 6.0 Strings from Microsoft Visual Basic
It mentions you need to input a length for your string inputs. When I create my dll no len is available for string parameters only Arrays. Is this a typo?
Also, In my LV code I have a path input. Can VB work with this? I have already converted my LV code to accept path as string...just wondering if I really have to do that.

Drugar,
Only string outputs (indicators) that are wired on the connector pane will show the length parameter selection when you try to build the dll.
I don't think VB accepts paths, so you should convert the path to string in LabVIEW before building the dll.
Zvezdana S.

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Create dll from labview

Hi all:
I am using labview 8.5 , i want to create dll for spacific vi , to use its output in another program like C++,
can any one help me to learn the steps to create dll from labview
thanks

You need the application builder (which is part of the professional distro).
In general you should every VI that you want as a function set to 'top-level'
If you right click on the builds in your project you have an option to build a DLL (if you have the application builder), from there on the help is available.
Ton
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Create DLL from labview and calling it from other application

I have an application built using Labview. I wanted to create DLL out of it. The application has
two String inputs start and stop buttons and two status indicators.
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Can some one help on this.
Solved!
Go to Solution.

Hi Yuvish,
1) They should be boolean inputs to your VI. But does it makes sense to provide a stop button input at the start of your VI? (THINK DATAFLOW!)
2) Yes, the LV-RTE is needed...
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Trying to create DLL from VI to use in TestStand.

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The controls and indicators are connected to the connectors. Also, answering an earlier post, the prototype information for the inputs and outputs are not automatically displayed. I can manually define the prototypes, but then the question is how does each prototype link to its corresponding parameter (by name?). I've also tied creating just a simple VI that has just one string input and one string output. I built the VI to a DLL and tried calling in TestStand and i get the same results. I've inserted the resulting header file after that build. Which, by the way, looks exactly like my other created DLL's header file. The difference in bold(the name of the VI). Which makes me thik that my build DLL process might be off.
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I have created PDF from hardcopy by using my scanner. After I run OCR option for my PDF by using Acrobat Pro 9. But "Text-to-speech" functionality of the PDF says that an error message comes up that says the page is empty when I turns on the read out loud option in Acrobat. Kindly help me to sortout this problems?

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Calling 64-bit dll from labview 8.2 on Windows7

Hello,
I have tried the LABview driver from the OMNIDRIVER (OceanOptics) package. But when calling functions from the “OmniDriver32.dll” , LABView is crashing and says that the memory is corrupted.
I am using LABVIEW 8.2 (32-bit) running on Windows 7 (64-bit). I have tried some LABView code examples given for LABview 7.1 and 8.0. These example are using the OmniDriver32.dll (not the OmniDriver64.dll).
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Create a DLL with asynchronous calls in LabVIEW for use in another environment.

Hello All,
I need to create a DLL in LabVIEW that is going to be used from inside a Delphi environment.
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Ok, after somem ore searching I found an example called "Building Asynchronous DLLs in LabVIEW".
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Can I create a dll from labview with more that one function name

I know that when I create a dll from C and then call it in labview using the call library function node I can see the different functions on the configuration screen. Is there a way to create a dll in labview to have more than one function name? No matter how many functions happen in my VI it seems to build into a dll under the same function name requiring inputs for every function, can this be avoided somehow?
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Dave

Each function corresponds to a separate VI. When creating the dll, on the Source Files tab of the app builder, click the Add Exported VI for each VI that you want. SubVIs of a main are not automatically exported and will not be available as separate function calls.

How do I call a LabVIEW created DLL from within Microsoft Excel (VBA)?

Hi,
I'm trying to get Microsoft Excel 2003 to call a function stored in a dll that I created using LabVIEW 7.1. The function is very simple and is called "binary_file_to_ascii". Basically it just reads a LabVIEW created binary spreadsheet file and outputs the columns as float arrays.
The function arguments are as follows:
INPUT : String that contains the path to the binary spreadsheet file
OUTPUT : Number of rows in the spreadsheet
OUTPUT : Number of columns in the spreadsheet
OUTPUT : Float array containing the elements in column 1
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I've attached to this post a ZIP file that contains all my code and a sample binary file.
Your help with this will be much appreciated. Thanks!
Richard
P.S. Here is the VBA code I'm using:
Private Declare Function binary_file_to_ascii Lib "C:\temp\binary_file_to_ascii\binary_to_ascii.dll" _
(ByVal binaryFile As String, ByVal nrows As Long, ByVal ncols As Long, ByVal column1 As Variant, _
ByVal column2 As Variant, ByVal column3 As Variant, _
ByVal column4 As Variant, ByVal column5 As Variant, _
ByVal column6 As Variant, ByVal column7 As Variant, _
ByVal column8 As Variant, ByVal column9 As Variant, _
ByVal column10 As Variant, ByVal column11 As Variant)
Private Sub load_binary_spectra()
Dim nrows, ncols As Long
Dim col1(), col2(), col3(), col4(), col5(), col6(), _
      col7(), col8(), col9(), col10(), col11() As Variant
Dim lRetVal As Long
Dim spectra_path As String
    spectra_path = "C:\temp\binary_file_to_ascii\sample_binary_file\sample_binary_file.dat"
    lRetVal = binary_file_to_ascii(spectra_path, nrows, ncols, _
              col1(), col2(), col3(), col4(), col5(), col6(), _
              col7(), col8(), col9(), col10(), col11())
    MsgBox (spectra_path)
End Sub
Message Edited by Richard Ballantyne on 07-25-2007 02:39 PM
Message Edited by Richard Ballantyne on 07-25-2007 02:39 PM
Attachments:
binary_file_to_ascii.zip ‏192 KB

Hi,
I don't know anything about Visual Basic, but here's my guess.
When you load the DLL with this line of code
Private Declare Function binary_file_to_ascii Lib "C:\temp\binary_file_to_ascii\binary_to_ascii.dll" _
(ByVal binaryFile As String, ByVal nrows As Long, ByVal ncols As Long, ByVal column1 As Variant, _
You are defining how the parameters are sent. It seems that all are sent by value (ByVal), but in the DLL header, some of the function's
parameters are defined as pointers(see the function prototype below, look for asterisk(*))
void __stdcall binary_file_to_ascii(PStr binaryFile,
                                                long *numberOfRows,
                                                long *numberOfColumns,
                                                float column1[],
                                                float column2[],
                                                float column3[],
                                              float column4[],
                                                float column5[],
                                                float column6[],
                                                float column7[],
                                                float column8[],
                                                float column9[],
                                                float column10[],
                                                float column11[]);
Can you define in VBA that you want to use pointer instead? Maybe by using ByRef (as by reference).
Hope this helps.

Building a dll with labview for CVI

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Hi,
It's seems that you have no exported function. What function do you have in your header file? did you tryed to create a really simple dll (doing an addition for example ) in LabVIEW only to verify that you are correctly creating the dll?
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Calling Dlls from LabVIEW

LabVIEW Gurus:
I am working with some software engineers who have no experience in LabVIEW. Unfortunately I have little experience in C/C++ to make sense of their inquiry.
Basically we are dealing with “Data Marshalling”. I will call a DLL and issue a command (string) and get back a 2-D array and an integer. So far so good.
The C/C++ programmer requested that I provide them with a pointer/memory address in which they will store data, so I can read it once the dll returns the array and integer. I browsed through the example online http://decibel.ni.com/content/docs/DOC-1690 and thought that if I wanted to read from the dll, the process is a simple as calling the appropriate function and configure the parameter (no pointers needed).
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Thank you,
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That example is pretty simplistic as it only deals with integers. In this case no pointers are required since everything is returned by value. When you're dealing with arrays, however, you need to deal with pointers. If you open the Example Finder (Help -> Find Examples) and search for "dll" you will see the "Call DLL" example. That contains many examples of how to call DLL functions with a wide variety of datatypes. I strongly suggest looking at that example. There is also a chapter in the LabVIEW Help on calling DLLs (Fundamentals -> Calling Code Written in Text-Based Progamming Language).
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You're dealing with arrays - this means you typically need to pre-allocate the memory in LabVIEW, and it sounds like that's what the DLL expects you to do. This amounts to using the Initialize Array function to create your 2D array of the appropriate size and datatype.
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Creating dll from Labview for use in VB

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