When I use the library function node call in real time, is loaded only once for all or load the DLL whenever it is called?

Similar Questions

• Despite indicating to the path, still have manually pointing DLL every time LV works using the library function node call

  I use the node of the library function call in LV 8.6. I checked the path to specify the box diagram and made directly in the DLL file that I use. Whenever I have started with Labview, I have to go to the diagram and physically find the DLL in one of my calls to make it work properly. Once I have do this everything seems to work as expected. Anyone else see this issue? Any suggestion would be appreciated.

  Thank you

  Steckman wrote:

  I use the node of the library function call in LV 8.6. I checked the path to specify the box diagram and made directly in the DLL file that I use. Whenever I have started with Labview, I have to go to the diagram and physically find the DLL in one of my calls to make it work properly. Once I have do this everything seems to work as expected. Anyone else see this issue? Any suggestion would be appreciated.

  Thank you

  Probably that DLL does not depend on other DLLs that reside in the same directory you point to in the configuration node dialog box call library. What is happening is this:

  Without going into this directory:

  LabVIEW applications Windows to load the DLL, Windows detects that it needs to load other DLLs and can not find in its standard search sites:

  (1) already loaded into memory

  (2) in the application directory (where the exe that began the current process resides in the LabVIEW IDE would be where is LabVIEW.exe)

  (3) in the system directory

  (4) in the Windows directory

  (5) any directory in the PATH environment variable contains

  (6) in the directory 'active '.

  Because Windows cannot find a person to load DLL he abandoned the main DLL loading and returns an error to LabVIEW.

  Now, you go to the configuration dialog box and point to the DLL. The dialog box browse file in LabVIEW uses the standard OS dialog box and this dialog box has the behavior obnoxious always update the "current" directory in the directory where a file got selected in. LabVIEW sees now that the path has "changed" and asks again to load the DLL. Yet once, Windows detects that it needs to load other DLLs too for this DLL but this time going over the search order, it will actually hit the DLL in the same directory and that's all fine.

  It is certainly NOT a problem of LabVIEW. LabVIEW does not and should not really need to know that a DLL needs other DLL loaded and more importantly should never try to think he can do better than Windows, it probably could, but is simply not his task of dependency DLL loading.

  It is your responsibility as a programmer and user of this DLL to know its dependencie, and if you did not write the DLL, to hit the original on his head programmer, if it has not documented these dependencies and make sure that these dependencies are actually properly resolved for Windows placing them in one of the places mentioned above

  ((2) is generally the best location for applications applications because it will not pollute the Windows directory or the user of the application system and 5) is the best for the development machine as you can add a directory to your PATH environment variable where you put the dll you need to develop a specific application.

  Rolf Kalbermatter

• Problems using "Appellant library function Node" statements with a DLL compiled by LabWindowsCVI

  I'm calling a simple C routine to a VI by using the node call library feature.  The example of ANSIdouble.vi, found inside the example called DLL.VI given in the help files does not work.

  But when I replace it with the same program (the source code is given in the DLL.VI call) compiled by LabWindowsCVI, it does not work.  In fact, it blocks Labview.

  I use LV 8.2.1.

  In addition, LabWindowsCVI does not compile the example as written code. I had to change the Sub _declspec (dllexport) in front of the function declaration cancel DLLEXPORT DLLSTDCALL and #incude the file "C:\Program NIUninstaller Instruments\CVI81\include\cvidef.h".  The compiler produces errors if not.

  The DLL.VI program to call is:

  #include "extcode.h".

  _declspec (dllexport) void ANSIdouble (double entry, double * output);
  _declspec (dllexport) void ANSIdouble (double entry, double * output)
  {
  * output = entry * entry;
  }

  The program compiled by LabWindowCVI is:

  #include "C:\Program NIUninstaller Instruments\LabVIEW 8.2\cintools\extcode.h".
  #include "C:\Program NIUninstaller Instruments\CVI81\include\cvidef.h".
  #include "TestC.h".

  DLLEXPORT DLLSTDCALL ANSIdouble(double input, double *output) Sub
  {
  * output = entry * entry;
  }

  where TestC.h is the statement:

  Sub DLLEXPORT DLLSTDCALL ANSIdouble(double input, double *output);

  The program has been compiled in a DLL that can be debugged with box of determination of objectives, copied as an attachment.

  Thanks to all those who can help you.

  TJ

  Solved with a call to Al on the help line.

  The correct procedure can be found by searching for "creating DLL" on the Web site of NOR.

  Using the page found by searching for "creating"DLL"helping within the CVI, is TOTALLY FAKE!  At least with my worm 8.1.1.

  Tom J

• Disable the use of structure in a lead time library function node increases

  I found that if I use a stureture disable to disable one of the outputs of a library function node call, the run time will be greatly increased. Can someone explain this?

  

  You can read this thread and benchmarking, I did there.

  Turn off debugging and check if the loss of performance you MENTION (but not quantified) is still there.

• Loading of the DLL string using the Code Library function node

  I experience now with the element of Code Library function node... what I wanted to do are, for example, I have compiled a. DLL file... which has a function that returns the pointer to string... function looks like:

  / * This function returns a pointer to the character string * /.

  char * pchar (int n)

  {

  char * str [] = {"error", "String1" and "Word2", "3"};

  Return ((n! = 1) & (n! = 2) & (n! = 3))? Str [0]: str [n];

  }

  but when I load into LabView DLL, a part of the chain on the screens to Panel frontal trash... any ideas why?

  p.s. when I do even with integer values... say my job is like int x = 5; Return x; and then I load in LabView to the digital indicator... it works great!

  So any ideas?

  thanx

  Cyrax says:

  I experience now with the element of Code Library function node... what I wanted to do are, for example, I have compiled a. DLL file... which has a function that returns the pointer to string... function looks like:

  / * This function returns a pointer to the character string * /.

  char * pchar (int n)

  {

  char * str [] = {"error", "String1" and "Word2", "3"};

  Return ((n! = 1) & (n! = 2) & (n! = 3))? Str [0]: str [n];

  }

  but when I load into LabView DLL, a part of the chain on the screens to Panel frontal trash... any ideas why?

  p.s. when I do even with integer values... say my job is like int x = 5; Return x; and then I load in LabView to the digital indicator... it works great!

  So any ideas?

  thanx

  You cannot return a pointer to the data stored on the stack. At the time when the function returns, the stack is reset to the State before the call to the function and in a multithreaded as LabVIEW environment probably long reused for other things when LabVIEW gets around to actually copy the returned pointer data.

  Since it is a read-only variable, you could create a permanent memory for string storage by declaring your variable static. This will create a memory area allocated globally for the string data (and also cause a compile error when you try to write in this area somewhere in your code, which is a good thing).

• VI Analyzer: the wire under the test object fails with call library function nodes

  Hello

  If I have a knot of function call with an ErrorIn and an ErrorOut library, the VI thread Test Analyzer "Thread under object" always fails with two hits in a library function node call.

  Double click to the salient facts occurrence lines error related to the call... node.

  The test fails, if the error lines are not connected.

  Thank you!

  H

  Sorry, created the CAR number is #208992.

  Kind regards

  Michael

• What is the right way to specify the location of the shared library in an a .lvlib function call library function node?

  I'll have a bit of a problem with how to specify the location of library shared in a call library function node it is a VI that is part of a library of LV. Here's a little background which may help.

  I do a lot of measures using spectrometers photo from several manufacturers.  Someone in my company developed a C DLL library, which provides a simple API for all the different spectrometers. To facilitate this DLL to use in LabVIEW, I wrote a .lvlib that wraps all the functions.  When I want to use the API, I simply include the .lvlib file in my project that allows me to drag and drop the wrapper s VI on my block diagram. When I created the .lvlib of VI, I specified the path in the call library node. /. * so it will always look in the local application to the DLL directory when I run.

  The problem is, when I load demand, LabVIEW you asks for the location of the DLL even if it's just there in the local directory! I tried to put copies of the DLL in the directory with the .lvlib, but he still refuses to find the DLL loading.  What I am doing wrong?

  You should in this simple case enter the full path to the DLL by navigating to it. If the DLL is on the same volume/drive that the VI containing the call library node LabVIEW will be internally store the relative path from the VI to the DLL (but still show the absolute path). If you move the DLL and screw together (so the relative location of the DLL to the VI remains the same) LabVIEW will always find the DLL.

  I don't think that the lvlib would add nothing to that.

• Crash when moving from a structure in a call library function node

  I am trying to use a type of Fortran (which I think is similar to a struct) in a LabVIEW call library function node.  I read a few remedies to this topic, but I'm not quite sure if I need to add the name of the parameter list of the node structure.  Now, when I run my VI it closed just LabVIEW entirely with no message.  I've attached the VI that I use and code source fortran, which compiles in my .dll.

  Any help is appreciated.

  Do you know if Fortran passes parameters by value or by reference?  I never used it.  A very quick search on the internet gives to think that the parameters must be passed by reference.  If this is the case, then you must pass the entire cluster as the parameter single, similar to Fortran statement.  You must also change the order of cluster to match the order in the Fortran statement.  Try the attached VI.

• Call library function node

  When using a call library function node, and the program came out, I get an error "has encountered a problem and needs to close" having to do with ntdll.  It does not stop the program from running properly, but it's annoying.  Any ideas?

  You should NOT specify the full path to a DLL system in the configuration dial the node of the library. This mess something in the newer versions of Windows. Instead just enter the name of the DLL only. It is sort of a bug in LabVIEW not automatically detect the system paths and shorten the path accordingly in itself, but this is how things have been for a long time and you just need to be a little careful.

  Also the return value must be really set up to be an integer of size of pointer, since a HANDFUL is really a pointer under Windows and that the first parameter is also better configured as such. The way you did works very well for LabVIEW 32 Bit but will misbehave in LabVIEW 64 Bit.

• help with call library function node

  I have problem with node function call library that I try to use velleman k8061 dll file to get this working labview

  all I'm trying to get the same problem

  but I chose one to explain it

  SetDigitalChannel
  Syntax
  PROCEDURE SetDigitalChannel (CardAddress: Longint;) Channel: Longint);
  Parameters
  CardAddress: The address of the previously opened card.
  Channel: Value between 1 and 8, which corresponds to the output channel to be resolved.
  Description
  The selected digital output channel is activated.
  Example of
  BEGIN
  SetDigitalChannel (0, 1);

  now, when I try to call the function of library in k8061.dll node and set up 2 a card address and one for the channel

  address of card type: type numeric & statistics: signed 32 bit intger

  channel type: numeric type & data: signed 32 bit intger

  function prototype

  void setdigitalchannel (int32_t, intg32_t channel address);

  I also configure error call library function node checking up

  now that I run it, I get error 1517 produced and tell me this mismatch between the calling conventions?

  problem solved

  thanx

• Connection of several call library function node

  

  First of all, I apologize if some of these issues are pretty basic. For my work, I have been teaching myself LabVIEW (using one of the books) for the last two months, in addition to a course of semesters of C++ software development. I have flowed through a few examples from the book and have searched these forums + google search, but I found the contradictory and confusing information on how to manage the C string data.

  I have attached a photo of the block diagram, the real VI and a manual describing the .dll file I'll call you. My real application is more complicated than what I've built here (I installed a trial version free at home, since I can't bring my lab computers files due to their having no do not have access to the internet...) There install everything for us, but it's a side story!), but deals with execution other than that, as I have the VI wrapped around an imposing event that runs based on which side a user presses the button, messages pop up additional user, etc..

  In the end, I'll implement a program which allows a user presses a single button that sends a bunch of instructions to an instrument, where requested orders have been compiled by the society of the instrument in a couple of .dll files. The instrument itself be held the certain function specifications, so there is not much need to worry to get somewhere, out string parameters to be stored, and there is no reception data of the instrument: it simply distributes liquid charges based on what parameters I pass to it. Given the same internet connection problems, I have to wait a few weeks for my IT team installed a decompiler of .dll file on the computer that has installed LabVIEW so that I hope that I can directly import the header file in the Import Wizard. I worked out of their manual without even being able to look in the .dll file (which may be more documentation), and they do not have the more detailed documentation on their data types (even if maybe these data types are public knowledge, and I'm just missing something). I went ahead and copied + pasted some of their function prototypes + example code pages 16 and 17 of the provided pdf (it looks like to me a C calling convention):

  'Functions of the DLL to talk to the PiezoElectronics.

  Public Function declare bfx_piezo_OpenPort Lib "bfx_piezocontrol.dll" (ByVal portname As String) As Integer

  Public Function declare bfx_piezo_ClosePort Lib "bfx_piezocontrol.dll" () As Integer

  Public Function declare bfx_piezo_ConfigurePiezo Lib "bfx_piezocontrol.dll" (ByVal ability As Double, ByVal VoltagePerStroke As Double) As Integer

  Public Function declare bfx_piezo_SetupPiezo Lib "bfx_piezocontrol.dll" (ByVal StrokeLength As Double, ByVal DownStrokeVelocity As Double, ByVal HoldTime As Integer, ByVal UpStrokeVelocity As Double, ByRef LoadTime As Double, ByRef LoadCurrent As Double, ByRef UnloadTime As Double, ByRef UnloadCurrent As Double) As Integer

  ' Search for electronics

  RC = bfx_autodetect_SearchPiezo (False, PiezoElectronicsPort, PiezoElectronicsDev)

  If rc = 0 then MsgBox("No electronics could be detected", MsgBoxStyle.Critical)"error message LogLabel.Text ="no electronics could be detected.

  On the other

  Action.Enabled = True '

  Device found-> activate the button LogLabel.Text = "Piezoelectronics" found on the Port & PiezoElectronicsPort

  RC = bfx_piezo_OpenPort (PiezoElectronicsDev) ' establish communication

  If rc = 0 Then LogLabel.Text = "open e".

  End If

  End Sub

  Private Sub Action_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Action.Click

  Dim rc As Integer ' to store the return code of the dll

  Dim LoadTime, LoadCurrent, UnloadTime, UnloadCurrent As Double ' to store the values returned by the dll

  RC = bfx_piezo_ConfigurePiezo (PiezoCapacity, PiezoVoltagePerStroke) ' Tell the dll of the distributor of physics

  If rc = 0 Then LogLabel.Text = "Configured distributor" "configure the parameters of dosage

  RC = bfx_piezo_SetupPiezo (stroke, beat down, HoldTime, ascending, UnloadTime, UnloadCurrent, LoadCurrent and LoadTime) rc += bfx_piezo_Repeat (repetitions, RepeatDelay)

  If rc = 0 Then LogLabel.Text = "Setup dosage settings."

  Only four interested features me search piezo, open port, configure piezo and piezo installation, as seen on my block diagram. My questions concern only the setup functions / openport piezo and how I built the library call nodes function, since these would also address how to set up the other two. When running VI, I get the error code is 1517, with installation function highlighted, leading me to believe that I have this feature badly adjusted upward (and Potentially openport, explained in the next paragraph).

  Function to open the port has two string parameters that are passed by reference, and configure the function takes one of the following strings as a call by value. Can I just wire them together as I did, or is it necessary to do something in the sense of adding a sub - VI GetValueAtPointer to dereference firstly, the pointer to the string and then spend the actual string on the second node?

  To specify the data types in the function library call nodes, I have all channels like C strings, double as double, return numeric values as integers signed 32 (each function returns a digital long I think that for debugging purposes), Boolean as an integer 16 bit signed (after that I forced my Boolean constant in an integer) and one of my numbers in Setup as an integer no signed, as I was told in an e-mail from the manufacturer of the instrument. Should we indicate the call launched by numbers as constants value, or not, since they are not explicitly defined as constants in the code provided? Since they have been specified not as long, I am right to assume signed 16-bit integer for the passage by the digits of the value? Is the Boolean value a 8-bit or 16-bit and signed? If the function has a numeric parameter as a value call, I guess by the wiring in a digital constant, that this value is transferred to the function?

  Again, I apoligize if these questions are too simplistic (and many of them), due to my limited experience programming and possibly scarce documentation of the company during the inspection. I look forward comments about the VI as well, if I had nothing at all just illegal/bad practice.

  Thank you for your time!

  First of all, I'm really not familiar with C/C++ dll, but I remember something the DLL must contain the standard C functions to properly accessible from LabVIEW. I don't know if this is the case here, but lets see more will enlighten this part.

  Second, whenever I have the chance to directly use the simple series commands, I go like this, and I create my own live LabVIEW. As I see in the attached pdf doc, it is possible to order the material through the series without using the DLL (on page 18). If these features meet your needs, I would really screw via VISA program, your life will be much easier...

  Edit: http://www.ni.com/tutorial/3702/en/

• [HELP] Call library function node...

  I have a DLL that has a function as follows:

  int GetMessageNameNumber (char * messageName [], const int MessageNumber);
  

   

  The function is used thus:

  char * MessageName = NULL;
  
  int MessageNumber = 0;
  
  ...
  error = HL1553API_GetMessageNumberName (& MessageName, MessageNumber);
  

  MessageName will contain the name of the message as a string.

  I saw the Devils own job trying to wrap this in a Labview module.  I have a knot of library function to call the above function, but I'm not sure what to set the parameter "MessageName" also!  I tried array of integers 8 signed bits, adapted to the Type of pointer to data in the table and then passed in an array of strings.  Whatever I do translates into LabView crash.  I know HL1553API_GetMessageNumberName works, because if I call it directly in TestStand it works fine.  I need LabView well!

  Any ideas?

  C a pointer to a string or an array of strings are completely ambiguous.

  char * something = char * something [].

  You can't tell the two apart from the syntax, but only from the documentation or an example of how the function is called. A C compiler treats the equal in terms of access (but a C++ compiler will do a syntactic differentiation when code syntax checking, with the possible result compile warnings when you are prompted to use a sufficiently high level of warning).

  The example shows that it is not a string array gets allocated by the caller and passed to the function, but a string pointer that is passed by reference. So the function will allocate a pointer and return it (a very atypical C practice at least for strings). This automatically raises the question when and how this pointer will be released? The documentation for this function should document the call from Manager memory allows to allocate this pointer and also point to the function to call to release. Ideally the library (DLL) provides an exported function for this purpose.

  Assume that everything I spoke so far is clear and available you need to cheat a bit LabVIEW. You need to configer a pointer size whole that is passed by reference. Now this whole in the diagram IS actually your channel. If you only need to pass this pointer to other library functions call that you're already doing. Otherwise if you need access to the contents of this string from the diagram LabVIEW, you will need to copy the information from this string to a real string of LabVIEW pointer.

  One way to do that is to use the export of the MoveBlock() C function that LabVIEW exports itself. I have explained this several times here on this forum and the MoveBlock research will no doubt find out these positions.

  Another slightly better way is to use the LStrPrintf() function which also exports of LabVIEW. To do this, you configure a library function call as follows:

  Library name: LabVIEW

  Function name: LStrPrintf

  Calling Convention: C

  Thread: both are possible, but the function is thread safe, so just use environment

  return parameter: int32 (there is a possible LabVIEW Manager error code)

  1st parameter: handle string of LabVIEW, passed by value

  parameter 2: C string pointer

  3rd parameter: integer pointer size, passed by valu

  Wire an empty string in the first parameter constant.

  Wire a constant containing the text '%s' without the quotes on the 2nd.

  The pointer to your thread on the 3rd string

  The function will return 0 as a return value and the content of the string on the side of the exit of the 1st parameter or a zero value indicating that a mistake to return back.

• call library function node to paste files

  Hello, I use the call library function node to paste the text to and from the Clipboard and works well.  Now, I'm trying to figure out how to paste a file from the windows file Explorer.  So if I highlights a file in the Windows File Explorer and press Ctrl-C, how can I use the library function node spit a file path?  It would be even better if I could highlight a bunch of files and then paste a table of paths, but that can wait.  Also, I use a Listbox MC, so I can't use drag-and - event trigger move a control path of the file.

  Also, I use WinXP and LV 7.1.

  Thank you

  Pat

  UPDATE

  I had little time to play with it and really out of curiosity on my part that I have whipped up a simple example to drag and drop from the Explorer in LabVIEW. I wrote the code in 7.1, but I have 7.1 on a virtual machine, and the DragQueryFiles did not work. I don't know if it was due to the fact that I was running on a virtual machine. I did, however, run the code in 8.2 and it works correctly. 8.2, I was able to drag a bunch of files in front of the VI, and the string table fills with file names. I am especially to see if it might work for you. You will need to get the Windows Message Queue library. Simply place the library in the same folder where you unzip the attached file.

• How to change the search engine when you use the functionality of Firefox Home button Search?

  In Firefox itself, I have configured duckduckgo as my default search provider.

  But when I use the host Firefox search button it is always defined on google and I don't see any possibility to change that?

  I love the Firefox Home button Search (or whatever we call it) otherwise, but it's annoying that it does not use the default Firefox.

  I use the Google Launcher now.

  Hi mrt181, it is planned to use the same search engine as in firefox - however, there is a bug at the moment, so it does not apply in all situations.
  usually, it will be enough to change the default engine in firefox back once to work around the problem in the search widget and get the same as set in the browser search provider.

• Firefox does not open with the tabs I had open when I use the renunciation and backup function. Firefox opens on my home page only. How to fix?

  When I use the function "Save and exit" has no effect. The next time I open Firefox it goes to my home page only.

  This has happened

  Each time Firefox opened

  Is 3 days ago

  If you use delete navigation, search and download history on Firefox in Firefox 3.5/6, or clear private data in Firefox 3 to clear the browsing history when Firefox is closed then in restaurant tabs at the last session (for example "save and exit" or "show my windows and tabs from last time ') does not work.