Call library function inside a conditional disable bug

i'm trying to call a function in a dll using the call library function inside a conditional disable structure.
one of the parameters is a pointer to a C structure.
here is the prototype:
short in myfunction(short in DevNum, void *pMetrics);
outside of the conditional disable, LabVIEW allows me to wire the pMetrics parameter to a cluster.
if i put the function inside the conditional disable, LabVIEW doesn't allow me to wire it.
as a workaround, i put the cluster inside the conditional disable as well.
any ideas?

Simply create a constant of the cluster and and put it outside the disable structure. Wire this constant to all inputs (left side terminal) of the Call Library Node. A Call Library Node (CLN) set to Adapt to Type does need a valid datatype to adapt too. This works from the outside side (right side terminal) of the CLN only if the according indicator is inside the same data structure. In older LabVIEW versions you actually had to always define the left side by wiring a constant or a dummy control to it.
This has to do with the algorithme that evaluates datatypes along wires. Making that algorithme go backwards (against the natural dataflow) inside one subdiagram without causing circular references or similar is already a challange. Doing that across diagram boundaries (case, disable, loop, etc. structures) is basically impossible without causing the entire edit operation to get very slow.
Message Edited by rolfk on 10-20-2009 08:28 AM
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Similar Messages

Call Library Function (DLL) Node Configuration

This issue was discussed few times on this forum (see for example http://forums.ni.com/ni/board/message?board.id=170&message.id=182911 ), but I still have a problem.
My question is - how to define the call to DLL without to specify its full path in order to be able to change the directory path without to change all calls to DLL functions within VI.
So, I did:
1. I put my DLL and my VI in the same directory.
2. I defined this directory in VI search path. This directory also defined as enviroment variable.
3. I use only one call to DLL in this specific VI (just as example in order to simplify the problem).
4. I define only DLL name without the path in CLF Node.
But, every time when I close CLF Node configution window, the program search for the DLL, find it and put full DLL path inside.
I will be very thankful if anyone can help me to overcome this problem.
Best regards,
Boris

Hello Boris,
To sum up the previous posts, when you specify the DLL when configuring the Call Library Function
node, internally LabVIEW stores in the VI either 1) the name of the
DLL, or 2) a relative path from the VI to the DLL (including the name
of the DLL). What's displayed in the dialog (in 'Library Name or Path'
field) is either 1) the name of the DLL, or 2) an absolute path that is
formed by appending the DLL's relative path to the VI's absolute path.
In
case 1, LabVIEW uses the Windows system search paths to load the DLL.
That is, it looks for the DLL in \windows\system32 folder, then if not
found there, it uses the folders specified in the PATH environment
variable, etc.
In case 2, LabVIEW tries to load the DLL from the
computed absolute path (VIs current path combined with the relative
path to the DLL that LabVIEW stored internally). And if not found
there, LabVIEW uses the VI Search Path (that can be set from Tools »
Options in the category of Paths).
So even though LabVIEW automatically puts an absolute path to the DLL
in the Call Library Function Node, as long as you will specify the
correct folder for the DLL in the VI Search Path, you should be Ok. However, if you want to
have a fixed location for the DLL, then it is best to keep it in the
\windows\system32 folder, and specify just the name of the DLL when
configuring the Load Library Function node (this way LabVIEW will not
automatically turn it into an absolute path).
Also, these knowledge base articles might be helpful:
Why Does My VI Prompt for My DLL Every Time I Open It?
LabVIEW Searching for a DLL Used in the Call Library Function Node
My Stand-Alone Executable Cannot Find My DLL, Even Though I Have Specified the Path for the DLL
Hope this helps and good luck with your application!
Shakhina P.
NIC

Call library function node with array of clusters using array data pointer

Hello all.
I am writing a LabVIEW wrapper for an existing DLL function.
The function has, as one of its parameters, an array of structs. The struct is very simple, containing two integers. I am using the call library function node to access it.
In Labview I created an array of clusters, where the cluster has two 32-bit integers as its members. So far, so good.
Now I have to pass this in to the Call Library Function Node. Here I am running into trouble.
I have used The topic in LAVA and The topic in the knowledge base as my primary sources of information, though I have read a bunch of forum topics on the subject too.
I do understand that I could write a new function which takes as a parameter a struct with the size as the first member and an array as the second, and I might just do this and have it call the regular function, but I was hoping to do it more simply.
According to the C file which LabVIEW generates for me from the CLFN when I choose "Adapt to Type" and "Array Data Pointer", the prototype it is expecting is:
int32_t myFunc(uint32_t handle, uint16_t channel,
int32_t FIFOnumber, void data[], int32_t numWords, int32_t *actualLoaded,
int32_t *actualStartIndex);
And the prototype of the function in my DLL is
int borland_dll myFunc(DWORD handle, usint channel,
int FIFOnumber, struct mStruct *data, int numWords, int *actualLoaded, int *actualStartIndex);
This looks like a match to me, but it doesn't work (I get garbage in data). From the topic in LAVA referenced above, I understood that it would work. It does not.
If I cast data to the pointer-to-pointer I get when I generate c code by wiring my struct to a CIN and generating, then I seem to get what I expect. But this seems to work when I choose "pointers to handles" too, and I would expect array data pointer to give a different result.
Is there any way to get this to work directly, or will I have to create a wrapper? (I am currently using LabVIEW 2011, but we have customers using 2009 and 2012, if not other versions as well).
Thank you.
Batya
Solved!
Go to Solution.

OK, here is more detailed information.
I have attached the VI.
This is the code from the "C" file created by right-clicking the CLN and creating a "C" file.
When the parameter in the CLN is set to "array data pointer":
/* Call Library source file */
#include "extcode.h"
int32_t Load_Transmit_FIFO_RTx(uint32_t handle, uint16_t channel,
int32_t FIFOnumber, void data[], int32_t numWords, int32_t *actualLoaded,
int32_t *actualStartIndex);
int32_t Load_Transmit_FIFO_RTx(uint32_t handle, uint16_t channel,
int32_t FIFOnumber, void data[], int32_t numWords, int32_t *actualLoaded,
int32_t *actualStartIndex)
/* Insert code here */
When the parameter is "pointers to handles":
/* Call Library source file */
#include "extcode.h"
/* lv_prolog.h and lv_epilog.h set up the correct alignment for LabVIEW data. */
#include "lv_prolog.h"
/* Typedefs */
typedef struct {
int32_t control;
int32_t data;
} TD2;
typedef struct {
int32_t dimSize;
TD2 data[1];
} TD1;
typedef TD1 **TD1Hdl;
#include "lv_epilog.h"
int32_t Load_Transmit_FIFO_RTx(uint32_t handle, uint16_t channel,
int32_t FIFOnumber, TD1Hdl *data, int32_t numWords, int32_t *actualLoaded,
int32_t *actualStartIndex);
int32_t Load_Transmit_FIFO_RTx(uint32_t handle, uint16_t channel,
int32_t FIFOnumber, TD1Hdl *data, int32_t numWords, int32_t *actualLoaded,
int32_t *actualStartIndex)
/* Insert code here */
When the parameter is set to "handles by value":
/* Call Library source file */
#include "extcode.h"
/* lv_prolog.h and lv_epilog.h set up the correct alignment for LabVIEW data. */
#include "lv_prolog.h"
/* Typedefs */
typedef struct {
int32_t control;
int32_t data;
} TD2;
typedef struct {
int32_t dimSize;
TD2 data[1];
} TD1;
typedef TD1 **TD1Hdl;
#include "lv_epilog.h"
int32_t Load_Transmit_FIFO_RTx(uint32_t handle, uint16_t channel,
int32_t FIFOnumber, TD1Hdl *data, int32_t numWords, int32_t *actualLoaded,
int32_t *actualStartIndex);
int32_t Load_Transmit_FIFO_RTx(uint32_t handle, uint16_t channel,
int32_t FIFOnumber, TD1Hdl *data, int32_t numWords, int32_t *actualLoaded,
int32_t *actualStartIndex)
/* Insert code here */
As to the DLL function, it is a bit more complicated than I explained above, in the current case. My VI calls the function by this name in one DLL, and that DLL loads a DLL and calls a function (with the same name) in the second DLL, which does the work. (Thanks Rolfk, for helping me with that one some time back!)
Here is the code in the first ("dispatcher") DLL:
int borland_dll Load_Transmit_FIFO_RTx(DWORD handle, usint channel, int FIFOnumber, struct FIFO_DATA_CONTROL *data, int numWords, int *actualLoaded, int *actualStartIndex)
t_DispatchTable *pDispatchTable = (t_DispatchTable *) handle;
int retStat = 0;
retStat = mCheckDispatchTable(pDispatchTable);
if (retStat < 0)
return retStat;
if (pDispatchTable->pLoad_Transmit_FIFO_RTx == NULL)
return edispatchercantfindfunction;
return pDispatchTable->pLoad_Transmit_FIFO_RTx(pDispatchTable->handlertx, channel, FIFOnumber, data, numWords, actualLoaded, actualStartIndex);
borland_dll is just "__declspec(dllexport)"
The current code in the DLL that does the work is:
// TEMP
typedef struct {
int control;
int data;
} TD2;
typedef struct {
int dimSize;
TD2 data[1];
} TD1;
typedef TD1 **TD1Hdl;
// END TEMP
int borland_dll Load_Transmit_FIFO_RTx(int handlertx, usint channel, int FIFOnumber, struct FIFO_DATA_CONTROL *data, int numWords, int *actualLoaded, int *actualStartIndex){
struct TRANSMIT_FIFO *ptxFIFO; //pointer to transmit FIFO structure
usint *pFIFOlist; //pointer to array of FIFO pointers to FIFO structures
int FIFOentry, numLoaded;
usint *lclData;
usint nextEntryToTransmit;
// TEMP
FILE *pFile;
int i;
TD1** ppTD = (TD1**) data;
TD1 *pTD = *ppTD;
pFile = fopen("LoadFIFOLog.txt", "w");
fprintf(pFile, "Starting Load FIFO with %d data words, data pointer 0x%x, with the following data&colon; \n", numWords, data);
for (i = 0; i < numWords; i++) {
fprintf(pFile, "%d: control--0x%x, data--0x%x \n", i, data[i].control, data[i].data);
fflush(pFile);
fprintf(pFile, "OK, using CIN generated structures: dimSize %d, with the following data&colon; \n", pTD->dimSize);
for (i = 0; i < numWords; i++) {
fprintf(pFile, "%d: control--0x%x, data--0x%x \n", i, pTD->data[i].control, pTD->data[i].data);
fflush(pFile);
// END TEMP
if ((handlertx) <0 || (handlertx >= NUMCARDS)) return ebadhandle;
if (cardrtx[handlertx].allocated != 1) return ebadhandle;
pFIFOlist = (usint *) (cardrtx[handlertx].segaddr + cardrtx[handlertx].glob->dpchn[channel].tr_stk_ptr);
pFIFOlist += FIFOnumber;
ptxFIFO = (struct TRANSMIT_FIFO *)(cardrtx[handlertx].segaddr + *pFIFOlist);
//use local copy of ptxFIFO->nextEntryToTransmit to simplify algorithm
nextEntryToTransmit = ptxFIFO->nextEntryToTransmit;
//on entering this routine nextEntryToLoad is set to the entry following the last entry loaded
//this is what we need to load now unless it's at the end of the FIFO in which case we need to wrap around
if ( ptxFIFO->nextEntryToLoad >= ptxFIFO->numEntries)
*actualStartIndex = 0;
else
*actualStartIndex = ptxFIFO->nextEntryToLoad;
//if nextEntryToLoad points to the last entry in the FIFO and nextEntryToTransmit points to the first, the FIFO is full
//also if nextEntryToLoad == nextEntryToTransmit the FIFO is full and we exit without loading anything
if (( (( ptxFIFO->nextEntryToLoad >= ptxFIFO->numEntries) && (nextEntryToTransmit == 0)) ||
( ptxFIFO->nextEntryToLoad == nextEntryToTransmit)) && (ptxFIFO->nextEntryToLoad != INITIAL_ENTRY)){
*actualLoaded = 0; //FIFO is full already, we can't add anything
return 0; //this is not a failure, we just have nothing to do, this is indicated in actualLoaded
numLoaded = 0;
lclData = (usint *)data; //must use 16 bit writes to the module
//conditions are dealt with inside the for loop rather than in the for statement itself
for (FIFOentry = *actualStartIndex; ; FIFOentry++) {
//if we reached the end of the FIFO
//if the module is about to transmit the first element of the FIFO, the FIFO is full and we're done
//OR if the module is about to transmit the element we're about to fill in, we're done - the
//exception is if this is the first element we're filling in which means the FIFO is empty
if ((( FIFOentry >= ptxFIFO->numEntries) && (nextEntryToTransmit == 0)) ||
((FIFOentry == nextEntryToTransmit) && (FIFOentry != *actualStartIndex) )){
*actualLoaded = numLoaded;
//set nextEntryToLoad to the end of the FIFO, we'll set it to the beginning next time
//this allows us to distinguish between full and empty: nextEntryToLoad == nextEntryToTransmit means empty
ptxFIFO->nextEntryToLoad = FIFOentry;
return 0;
//we reached the end but can continue loading from the top of the FIFO
if ( FIFOentry >= ptxFIFO->numEntries)
FIFOentry = 0;
//load the control word
ptxFIFO->FifoData[FIFOentry * 3] = *lclData++;
//skip the high of the control word, the module only has a 16 bit field for control
lclData++;
//now put in the data
ptxFIFO->FifoData[(FIFOentry * 3) + 2] = *lclData++;
ptxFIFO->FifoData[(FIFOentry * 3) + 1] = *lclData++;
numLoaded++;
//we're done because we loaded everything the user asked for
if (numLoaded >= numWords) {
*actualLoaded = numLoaded;
ptxFIFO->nextEntryToLoad = FIFOentry+1;
return 0;
//if we reached here, we're done because the FIFO is full
*actualLoaded = numLoaded;
ptxFIFO->nextEntryToLoad = FIFOentry;
fclose (pFile);
return 0;
As you can see, I added a temporary diagnostic with the structures that were created in the "Handles by value" case, and print out the data. I see what is expected, whichever of the options I pick in the CLN!
I understood (from the information in the two links I mentioned in my original post, and from the name of the option itself) that "array data pointer" should pass the array of data itself, without the dimSize field. But that does not seem to be what is happening.
Batya
Attachments:
ExcM4k Load Transmit FIFO.vi ‏15 KB

Execution time for Call Library Function Node

I am experimenting with the Call Library Function Node block in LabVIEW and am curious if it should be running faster than what I'm seeing. For testing purposes, I have compiled and transfered to my RT target the .out file from the KB article http://digital.ni.com/public.nsf/allkb/81D1172E3C28A5E4862575CC0076A230 (I'm using the vxworks 6.1 version). The function in the .out file just multiplies two inputs together, adds a constant, and returns the result. I have put this inside a 1 kHz timed loop with a commanded period of 1 ms and via the Ticks(ms) block and shift registers I calculate the amount of time per loop execution. This process is apparently taking 5 ms per cycle and to me that seems slow. Is that roughly the correct execution time for this kind of setup? I will attach my test .vi file.
What I'm using:
Windows 7
LabVIEW 2009 SP1
NI-cRIO 9024 with NI-RIO 3.4.0
Solved!
Go to Solution.
Attachments:
test DLL.vi ‏31 KB

First off, the way you are doing timing isn't necessarily accurate because you don't know when the tick count VI is being called. For example, if it gets called on one iteration after your call library node executes, and the next iteration it gets called before the CLFN it executes, the subtraction doesn't include the call of the CLFN so you aren't seeing the true time it is taking for the dll to be called.
Where it says "error" on the top left hand corner of your loop. left click and choose previous iteration timing. Also, do you have the ability to choose a 1 Mhz clock? Are you sure it's actually being run on the RT and not on your PC? Running it on the PC would definitely make it difficult to execute at a 1 kHz rate.
CLA, LabVIEW Versions 2010-2013

Failed to run parallel path when using call library function node in LV2009

I have a problem with two parallel paths not being run in parallel on LabView 2009.
See the image below.
This code initializes an external device, the upper part contains a call library function node to download my code into the device. When done, the function returns and the "Done" flag is set to True.
The lower part contains a call library function node to check the download status, reporting the percentage of downloaded code.
This updates a progress bar that is referenced by the calling VI module and this works fine in LV 7, 8 and 2011. The lower path of the VI updates the progress bar while the CLFN in the upper part is still downloading code to my device.
Somehow, in LV2009 this does not work when running this inside my application. When running just the calling VI (the window showing the progress bar) it works but not when that VI is called by my application.
Is there some limit on parallel threads that is different in 2009 than in other versions ?
Or is there some other problem in 2009 that might cause this problem ?
My labview version is 9.0f3 (32-bit).
Regards,
Rob

I've just installed the DETT tool and checked what the different versions of LabView do.
In LV2009 the application instance runs in a thread (5) but the modal dialog (the VI above) then drops to thread 0 and stays in thread 0.
In LV2011, stays in the same thread as the application instance and only a trigger event (this could be the progress bar reference?) is executed in thread 0.
So it seems there is a 'feature' in LV2009 where modal dialogs are by default not following the preferred execution system set in the VI properties ...
When I change this from "same as caller" into another thread (I used "other 1") then my progress bar works as expected.
I'm not a LabView thread expert (not even a novice ) so I'm just guessing that "other 1" as a thread is OK. This VI only runs during startup of the application to download the code to my device.
To answer Ben's question: "What thread does a modal VI run in?":
In LV2009, the modal VI runs in thread 0 (UI thread ?). When the preferred execution system is set to another thread, the modal dialog still starts in thread 0 but then switches over to the other thread.
In LV2011, the model VI runs in the caller's thread (preferred execution system set to "follow caller") from start.
Thanks,
Rob

Parameters into Call Library Function Node not being passed

I am trying to configure an instrument using IVI Instrument drivers. In the first vi that does this, the instrument (a sig gen) is being set correctly to the desired frequency and power. In a second vi I try to change the frequency and power, the sig gen does not change.
If I run the second vi stand-alone with the original settings, again there is no change. But if I change the value of frequency or power by any amount, that parameter is now set properly on the sig gen.
When I look at the IVI vi, I can see that the parameters I send in are getting to the Call Library Function Node.
Any idea what the problem is.
Thanks.
p.s., Are there instructions on how to paste a picture or link to a vi into my post. This question would have been a lot easier and clearer to ask.

Hi cgantz,
While it sounds, possibly, like a "state-caching"-related bug in the IVI driver, it certainly would be good to have a look at your code. Look a the bottom-left area of the "Message Body" when replying - there's an "Attachment" tool for this purpose!
Cheers.
"Inside every large program is a small program struggling to get out." (attributed to Tony Hoare)

How to call a C pointer from call library function node

I have a client/server application which the client I am trying to develop using Labview. When I use to communicate the server and the client using the program provided by the manufacter, the system works perfectly.
Now, I am trying to develop a system using labview, because I need to get another things.
I have the DLL provided by the manufacter and the .h too, so I can check the functions parameters. One of these functions needs to be called using a struct element. Probably, the function's DLL instantiates the elements of this struct. I use the call library function node to do it.
When I receive the data, the function returns to me the struct that I passed as a parameter before, and then I can read all the elements of the struct, except the string element that returns nothing. The struct elements that are numerical, I can read them perfectly.
Another thing that is important to say, is that the string data was not returned in fact by the DLL function that the system calls. I have to pass a pointer (I use it as unsigned 16 in Labview, but I tried before as string and unsigned 8) as a parameter, and this pointer will point to the memory location that the string is. When I try to read what is returned by the function, I can read nothing. The same function returns that the size of data that is returning is 17 bytes.
How can I solve it?
Thank you in advance

Did you take a look at the example that ships with LabVIEW that shows how to do all sorts of data passing to DLLs. I believe your situation is one of the examples listed. You can find the example VI in the "<LabVIEW install directory>\examples\dll\data passing" directory.

Passing arrays with Call Library Function does not work after application builder

Calling a DLL with Call Library Function which requires an array of data works correctly in Labview, but after building an exe with application builder, the call no longer works. Dereferecing the pointer in the DLL retuns all 0s and not the actual values.
Solved!
Go to Solution.
Attachments:
TEST.zip ‏28 KB

I did not run your code because it is a little unclear to me what it does.
Two things:
First, is the DLL you are calling the DLL-ified version of PopUpNames.vi? Then the problem is likely that the panel is not being built into the DLL.
When LabView builds an application / dll, it strips the front panel and block diagram from all VIs that it doesn't think need to show a panel at run time. This reduces file size and increases code security. The App Builder's panel inclusion logic can be overridden by Build Specifications -> Source File Settings -> Remove front panel. A better method is to put a property node on a control in a window you want to show marking it "visible"; this is sufficient to tell the App Builder it should keep the panel.
Currently Source File Settings shows "no dependencies" (clearly incorrect---another evil side effect of Express VIs I guess) but if you change the settings as shown below to keep ALL panels, one might hope the App Builder can figure it to keep the panel when it deconstructs the Express VI. (Alternatively convert the Express VI into a regular one.)
A second comment: I am a bit flummoxed at the larger goal here. You are calling LabView DLL from LabView, which doesn't make a lot of sense, so I assume your larger goal is to call LabView from C or vice-versa. In that case be aware that your DLL is x86 (32-bit) but you are passing 64-bit ints as your pointers. In this case it is 32-bit LabView with 32-bit pointers in embedeed in 64-bit containers calling 32-bit LabView with 32-bit pointers in embedeed in 64-bit containers, so it all works, but if your going to call this from C or whatnot you're going to have to follow that same design.
When calling C code the LabView Call Library Function does have a "unsigned pointer-sized integer" data type that always appears to be 64 bits in the dev env but which actually passes a 64 or 32-bit int to the DLL depending on the environment. The "pointer sized int" has to be 64 bits in the "LabView" part of the code because LabView's strong typing requires the data type to be determined at compile time. Casting all pointers to the largest data type in LabView makes it possible to write platform-independent code, but down at the Call Library level you still have to put the right number of bytes on the stack.

Window doesn't close wheh Call Library Function Node set to Run in Any Thread

This is a problem regarding Call Library Function Nodes running in the UI thread or any thread.
I have a camera which has its own API supplied as a dll. I have created a set of VI wrappers which each call a function in the dll through a Call Library Function Node.
Initially each CLFN was set to 'Run in the UI thread' (the default).
To start the camera streaming images I call (through a CLFN)
ICubeSDK_Start(int CamIndex, Hwnd, ImgHandle, bool Preview, bool callback);
If Preview = True then the image is displayed in a preview window.
If ImgHandle = NULL a default preview window
is used.
In the CLFN definition I define:
ImgHandle as a U32
Preview as a I32
To stop the camera streaming images I call
ICubeSDK_Stop(int CamIndex)
In the actual implementation I set ImgHandle = 0 (NULL) and Preview = 1 (true).
This all works fine, and a preview window is opened and images displayed. When I call ICubeSDK_Stop the preview window is closed.
However, I would prefer to set the CLFN to 'Run in any thread' because
a) when run in the UI thread the preview window randomly gets sent to the back when I switch focus between open VI windows (presumably because it is in the same thread as the VIs)
b) I don't want to put unnecessary stuff in the UI thread
c) my (naive?) understanding is that it is safer to run in any thread
So I have set all CLFNs to 'Run in any thread'
When I do this the preview window opens OK, and behaves like any other non LabVIEW controlled window in terms of focus. But when I call ICubeSDK_Stop() the preview window does not get closed properly, it just shows a blank image. I can't close it manually, there is no X in the corner and no option to close it from the taskbar. To get rid of it I have to close the LabVIEW project it is spawned from, which often results in a crash. It does appear as a separate item in task manager but if I 'end process' it, LabVIEW closes (and often crashes) as well.
If I change only the CLFNs that call the Start and Stop functions back to 'Run in the UI thread' then it all works fine again, except that the preview window gets sent to the back randomly as before.
So, what do I have to do to get the preview window to close properly if I set the CLFN to 'Run in any thread'.
Alternatively, is there a way to close the window programmatically (ie force it to close) after I have called ICube_Stop.
Thanks
DAve

Hi Dave,
The "Run In UI Thread" switches from the thread the VIs currently executing in to the user interface thread. If you select "Run in Any Thread", the Call Library Function Node continues in the currently executing thread. By default, all Call Library Function Nodes run in the User Interface thread.
Before you configure the Call Library Function Node to run in any thread, you have to make sure that the code is thread safe. Code is thread safe when it does not store any global data (e.g. global variables, files on disks, etc.), does not access any hardware, does not make calls to any functions, libraries or drivers that are not thread safe.
Unfortunately, since you said that your DLL accesses hardware, it is not recommended to use "Run in Any Thread." This is probably why you are seeing the crash.
If your preview window gets sent to the back you can programmatically bring it forward. Here is an example of how this can be done: http://decibel.ni.com/content/docs/DOC-4551
If you want to completely close the window down you can do so as described in this link: http://digital.ni.com/public.nsf/allkb/81E9C1441900FFCE8625748F0055DBB0?OpenDocument
I also thought you might find this useful: http://zone.ni.com/devzone/cda/tut/p/id/3009
I hope this helps.
Regards,
Mahdieh G
Applications Engineer
National Instruments UK&Ireland

How can I debug the Call Library Function at run-time

I've written a VI using the CLF to call a DLL which was compiled off-site by another engineer using MSVC. Even though the VI runs without flagging any errors, the VI is not doing what I expect. Is there any way of finding out if the DLL is been called correctly? The first function that is called doesn't return any value, but I think that it should. Does this mean that the DLL is not being called correctly? Note also that the DLL works fine with a JAVA GUI.

Make sure that you are specifying the proper function prototype in the call library function. If you are slightly off the call will not work properly. Ask the offsite engineer to provide you with this data. Another tip is to build the dll with the option to show front panel when called. You can actually popup the dll like you would a subvi. If you design it with test indicators showing on the front panel that is a great way to determine if it is working. Hope this helps.
BJD1613
Lead Test Tools Development Engineer
Philips Respironics
Certified LV Architect / Instructor

Problem in call library function

Hi,
I encountered some problems when using call library function node.
After i select the path in configuration of call library function node, an error message is shown as 1st attachment.
After i tick and the specified path on diagram, link the path name to the node, and run the program. Another error message is shown as 2nd attachment.
Is my dll file got problem? Or i have done a wrong setting?
Here i have attached my dll file.
The dll file is built by Microsoft Visual Studio 2008.
Please kindly advise.
Thank you.
Attachments:
picture1.JPG ‏14 KB
picture2.JPG ‏17 KB
CodeUtil.zip ‏152 KB

TanTan wrote:
Hi,
Is my dll file got problem? Or i have done a wrong setting?
It seems to be compiled for WinCE. Assumed that you have Win2000/XP/Vista/7. Check your MSVC build settings.
Andrey.

Calling a function inside a symbol?

Hi there,
I'm one of those flash-devs that are trying to get Edge Animate to do what I usually do in Flash, so I might be doing this the wrong way, but I've got a symbol with a function "inside" on my stage, and I wanna call that function from the stage.
I've been trying to use sym.getComposition().getStage().getSymbol("symbolName").functionName(); but it doesn't work.
I don't have any problems manipulating the symbol itself by calling .play() or .hide() so I know the path works....can anyone show me the right syntax to call a function inside a symbol?
Thx in advance

Hi Abnesher,
An important principle to grasp is that symbols (and the stage is one of them) lies in parallel, despite the fact of instances of different symbols being nested one in another (and all in fine nested in the stage).
The consequence is that from inside your nested symbol you have no direct visibility of the function defined inside the stage symbol !
Inside the Stage symbol, in the document.compositionReady event handler :
sym.yourGlobalFunction = function( firstParameter)
// your stuff
Inside another symbol, in one of its events handlers :
sym.getComposition().getStage().yourGlobalFunction( 5);
Gil

Problem with Call Library Function. Want to pass a string and return a string, but my compiler does not recognize "CStr" and Labview does not recognize my "char *function()" callout

Hi, I'm trying to use a .DLL I wrote in Visual C++ .NET. The Call Library Function generates a function prototype of "CStr Parser(CStr arg_raw)"
but my compiler won't accept this. So I change it to how C normally deals with strings "char *Parser(char *arg_raw). Now the Call Librafy Function does not find "Parser" in my .DLL though it is definitely there!
Help!
-Fong

Hello
You will need to include extcode.h in your C file. You can find this under ..\LabVIEW\cintools folder.
The include has all the defines you will need.
Bilal Durrani
NI
Bilal Durrani
NI

Call library function node in a loop

Hello All,
I am currently using a call library function node in a while loop which calls a third party dll to process and recieve some data.
My question is, if I am using this function in a while loop, what exactly happens?
Does the dll get called in each loop iteration, or does it keep the called dll loaded in memory and just pass the values to it to process data?
Also, if the answer to the above question is that it will make calls to the DLL in each iteration, how can we keep it loaded in memory always? I mean, if the DLL is a .NET application DLL, I believe the main .NET application which uses this DLL won't do multiple calls to the dll, rather it will keep it loaded in memory.
Thanks
FraggerFox!
-FraggerFox!
Certified LabVIEW Architect, Certified TestStand Developer
"What you think today is what you live tomorrow"

Hi,
the DLL will stay in memory as long as there is a program running which has not closed (unloaded) the DLL.
Doing repetitive calls to the DLL is irrelevant in this context. LV opens the DLL as soon as needed and will only unload it when there is no VI in memory which has a CLN to that DLL...
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome

PDA: Calling library functions - seems to link the stubbed .cpp file instead of the DLL

I'm having trouble developing a Lab View PDA module that calls a DLL built using Visual C++. The DLL functions correctly when called in a non-PDA VI. My issues seem to be with porting to the PDA.
My configuration:
- Lab View 8.5 with the PDA 8.5 module
- Visual Studio 8.0 with the Windows Mobile 6.0 SDK
- ASUS 626 PDA with an Intel PXA70 procesor running Windows Mobile 6 Classic
Following the PPCBatt example code provided with the PDA module, I have:
- used extern "C" to prevent name mangling
- placed the DLL built with the Windows Mobile SDK in the \Windows directory on the PDA
- created a stub Win32 DLL and lib
- created a stubbed cpp file whose functions only return zero
- included the stubbed cpp and lib files in the build spec / source files / additional files
- placed Call Library Function nodes on my PDA VI, selected the function names, set the parameter types
- built and deployed the executable, both with and without debug
When I set the library path property of the Call Library Node, the functions appeared in the function name pulldown, but the parameters did not populate. I had to manually add them and set their types. The help page says they would autopopulate when the function was selected.
I've debugged the VI, and the Library Function Call nodes are being called. It seems the build is linking the code from the stub C file provided in the additional files portion of the source files property page, instead of adding hooks to call the DLL on the PDA. As a test, I changed an output parameter in one of the functions in the stubbed cpp file - the changed value showed in the front panel indicator.
What am I doing wrong?
Dan

Hi Dan,
I'm not sure if I understood you problem fully. When calling external code with LabVIEW PDA, the DLL acts as a stub DLL with the correct function prototypes for the C code that you want to call. Here's a Knowledge Base article that might help explain about calling External Code in LabVIEW PDA.
Regards,
Stanley Hu
National Instruments
Applications Engineering
http://www.ni.com/support

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