Using an external DLL with "Call Library Function"

Hi!
I am trying to use an external DLL which is used from Visualbasic & Delphi:
http://www.keb.de/common/tools/KEBCOMDriver.zip
the protKEB.dll accesses the serial port to control an KEB frequency
inverter.
Unfortunatly there is no prototype header file for the DLL (no help on that
from KEB).
I only have a VisualBasic example program which works with the DLL.
(Unfortunatly I am no Visual basic expert)
To initialize the com port I have to use the function: setprotproperties &
getprotproperties
they are declared as:
'Setting the protocol properties
'ctrl is a pointer to a data structure of type tProtProperty
Declare Sub setprotproperties Lib "protkeb.DLL" (ctrl As Any)
'Reading the protocol properties
'ctrl is a pointer to a data structure of type tProtProperty
'the desired protocol is entered in ctrl.prottype before calling
Declare Sub getprotproperties Lib "protkeb.DLL" (ctrl As Any)
and tProtProperty is:
Public Type tProtProperty
ProtType As Long 'Type of Protocol (tProt)
TimeOut As Long 'ALL protocols
Baudrate As Long 'ANSI, HSP5
Comport As Long 'ANSI, HSP5
Flag As Long 'ANSI, HSP5: 01 = Sendslow
/ IP: 01 = UDP
Port As Long 'IPort number
Txtlen As Byte 'IP : length of following
text or 0
txt As String * 100 'IP : IP-Address or name
(maximum length)
End Type
I already tried to use a cluster with tProtProperty entries as an Input for
the function
setprotproperty in a call library function with:
Parameter Type : Adapt to type
Data Format: Pointer to Handle
but I always get an "exception within external code....."
What am I doing wrong?
How does a cluster & a "call library function node" look like that works?
Any help is really appreciated!
thanks
tom
,-Thomas Kerberger Physikalisch-Technische Bundesanstalt-.
| Abbestr.2-12 D-10587 Berlin fon: +49-30-3481338 |
| mailto:[email protected] fax: +49-30-3481386 |
`--------Labor 7.33 Messung thermischer Energie---------'

Thomas,
LabVIEW cannot call a DLL that has structures directly, you will need to create either a wrapper DLL or CIN that will take in all of the data individually construct the structure, and send it to the DLL function.
For more information on what a cluster looks like in native code, I would suggest creating a simple cluster, creating a Call Library Function Node on the block diagram with a cluster input. Then right-click on the Call Library Function Node and choose "Create .c file". This will generate the data structure for the cluster and give you a better feel for it. I would then suggest going to the Using External Code in LabVIEW manual that can be found in the LabVIEW Bookshelf (Start»Programs»National Instruments»LabVIEW 6»LabVIEW Manuals or »LabV
IEW 6.1»Search the LaBVIEW Bookshelf).
There is also the following: Developer Zone: Passing a Variety of Data Types from DLL to LabVIEW.
Randy Hoskin
Applications Engineer
National Instruments
http://www.ni.com/ask

Similar Messages

Call multiple functions from same dll with call library function

hi,
i am working on a project in wich we need to make a UI to read out a sensor network.
the UI should be usable in any project, but every node needs a different piece of code depending on the type of sensor with wich it is equipt.
so i need to be able to call different pieces of code when i need them, and still be able to use the UI in future projects with possibly new types of node we now don't have.
so someone told me to use DLL's, cause then i would be able to call the code i need the moment i need it.
but i have never worked with DLL's (just learned about this option 3 day's ago) so i have a question.
i know i can dynamicly change the DLL i call with the call library function, but can i dynamicly change the function i call from that DLL ?
or do i have to put a new call library function for each function i want to call, even if its from the same DLL ?
kind regards,
stijn

nazarim wrote:
ok so there is no (easy and ubderstandable) way for me to dynamicly change wich function i want to call from a certain DLL.
but now i started wondering, the path on the call library function is not ment to dynamicly change a DLL
but it does work so, if i am carefull, can i use it for that purpose or will labview give me a series of problems once i start using it in larger programs ?
Thepath on the Call Library Node can be used to load a different DLL. Obviously since you can't change the function name your other DLL would have to export exactly the same function name and of course with the same parameters. This is seldom the case so it is not the main use of the path input to the Call Library Node. It's main use is as indicated to load DLLs at runtime rather than at load time of a VI. So that an application can run even when the DLL is missing, until the moment the functionality from that DLL is needed.
If you can make sure that all your DLLs export the same function name with the same parameter you can use the Call Library Node to call into different DLLs through the path input. If however you would need to call different function names you would have to resolve to some DLL which does do the dispatching and invocation using LoadLibrary() and GetProcAddress(). But unless you need to go with DLLs for some reason using the Call By Reference Node can give you an even more flexible approach.
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Crash "DAbort 0x37C03D in MemoryManager.cpp" when calling DLL with "Call Library Function Node"

Hi all,
I would like to work with a LabVIEW program that I did not programm by myself.
In this programm an external DLL needs to be called. in the Momente this dll ist called with the "Call Library Dunction Node" LabVIEW crashes with this Error Message:
DAbort 0x37C03D in MemoryManager.cpp
Attached is the entire Log.
The programm runs on the computer of the original programer.
I have never handeled with DLLs or something like that before, so I have absolutely no idea how to rsolve this problem.
Thanks for your help!
Attachments:
lvlog.txt ‏2 KB

A DLL can be compiled by different compilers. By "generic" C DLL, i refer to ANSI C (so no C++, no Borland C or something else).
My question is raised as parameters, esp. arrays and strings, can lead to this behavior when used in the wrong way (including "Calling Convention").
Also, interfacing with the LV memory manager can lead to crashes like this, but this wouldn't be a "generic" DLL as it binds to LV (due to LV API calls).
Without a better knowledge on the DLL and its functions, there is not much we can help you with.
Where does the DLL come from?
Norbert
CEO: What exactly is stopping us from doing this?
Expert: Geometry
Marketing Manager: Just ignore it.

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.

Probel with call library function: I have a dll based on a complicated struct data type. How can I pass this structure?

The data type is
typedef enum {false, true} bool;
typedef float flt4;
typedef double flt8;
typedef int i32s;
typedef unsigned int i32u;
typedef short int i16s;
typedef unsigned short i16u;
typedef signed char i08s;
typedef unsigned char i08u;
struct t_UnwrapData {
struct {
i08u flags;
i16u unwrap_m;
i08u weight_m;
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flt4 *ph2pi;
flt4 *weight;
flt4 *gamma;
flt4 *phase;
i08u *flags;
i08u *neigh;
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i32s r,c;
i32s x0,y0,xSz,ySz;
flt8 unwTime;
flt4 binCut;
Please Could someone help me suggesting how I pass this dat
a type to call library function?

Hi Setu,
Here is a solution that I have been playing to return back an array of clusters
typedef struct
int32 dimSize;
uInt8 array[1];
} LVU8;
typedef LVU8 **LVU8Hdl;
typedef struct
U32 DeviceId;
U32 VendorId;
U32 BusNumber;
U32 SlotNumber;
LVU8Hdl SerialNumber;
} LVDEVICE_LOCATION;
typedef LVDEVICE_LOCATION **LVDEV_LOC_HANDLE;
typedef struct
int32 dimSize;
LVDEVICE_LOCATION cluster_array[1];
} LVDEV_LOC_ARRAY;
typedef LVDEV_LOC_ARRAY **LVDEV_LOC_ARRAY_HANDLE;
LVPLX_API void GetAllDevices(LVDEV_LOC_ARRAY_HANDLE cluster_array)
int i,j;
int numDevices = 3;
DSSetHandleSize(cluster_array, sizeof(int32)+3*(sizeof(LVDEV_LOC_ARRAY)+(sizeof(int32)+16*sizeof(L
VU8))));
(*cluster_array)->dimSize = 3;
(*((*cluster_array)->cluster_array[0]).SerialNumber)->dimSize =16;
(*((*cluster_array)->cluster_array[1]).SerialNumber)->dimSize =16;
(*((*cluster_array)->cluster_array[2]).SerialNumber)->dimSize =16;
for(i=0; i<3; i++)
((*cluster_array)->cluster_array[i]).BusNumber = i;
((*cluster_array)->cluster_array[i]).VendorId = i*5;
for(j=0;j<16;j++)
(*((*cluster_array)->cluster_array[i]).SerialNumber)->array[j] = (10*j)+i;
The code doesnt do much but returns back 3*cluster which the array in my cluster is sized for 16. The problem I've been having , was ensuring I have allocated enough memory to handle the complete structure. This works for me, now all I have to do is put the real code in which get my array of data from the instruments.
Hope it helps
Regards
Ray Farmer
Regards
Ray Farmer

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
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Bilal Durrani
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VI analyzer: Wire under object test fails with Call Library Function Nodes

Hi,
If I wire a Call Library Function Node with an ErrorIn and an ErrorOut, the VI Analyzer Test "Wire under Object" fails always with two occurrences per Call Library Function Node.
A double click to the occurrence highlights the error lines connected with the call... node.
The test does not fail, if the error lines are not connected.
Thanks!
H
Solved!
Go to Solution.

This became a problem when Call Library Nodes got error terminals (and optional path terminals) in LabVIEW 8.20. I should be able to get a fix in to VI Analyzer Toolkit 2010.
Thanks for taking the time to report the bug.
Darren Nattinger, CLA
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How to use structure pointer with Â« Call Library Function node Â» in LabVIEW

I use GetTimeZoneInformation from kernel32.dll. It definition is :
DWORD GetTimeZoneInformation( LPTIME_ZONE_INFORMATION lpTimeZoneInformation );
Where
lpTimeZoneInformation
[out] Pointer to a TIME_ZONE_INFORMATION structure to receive the current time-zone parameters.
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/base/gettimezoneinformation...
I don't know how to set this parameter with my cluster based on the TIME_ZONE_INFORMATION structure.
Your help will be appreciate
Thanks
INKSPEC

INKSPEC wrote:
I use GetTimeZoneInformation from kernel32.dll. It definition is :
DWORD GetTimeZoneInformation( LPTIME_ZONE_INFORMATION lpTimeZoneInformation );
Where
lpTimeZoneInformation
[out] Pointer to a TIME_ZONE_INFORMATION structure to receive the current time-zone parameters.
http://msdn.microsoft.com/library/default.asp?url=/library/en-us/sysinfo/base/gettimezoneinformation...
I don't know how to set this parameter with my cluster based on the TIME_ZONE_INFORMATION structure.
Your help will be appreciate
Thanks
INKSPEC
If creating a wrapper DLL which does the conversion for you is not an option (I think it won't since that would require C programming and if you knew C programming you wouldn't ask this here) then you will have to create a byte array of appropriate length and just configure the Call Library Node to pass this array as an Array of unsigned bytes and as C pointer.
On return you will have to copy out the interesting data at the right position.
First the length of this structure would be:
typedef struct _TIME_ZONE_INFORMATION {
LONG Bias; 4
WCHAR StandardName[32]; 32 * 2
SYSTEMTIME StandardDate; 8 * 2
LONG StandardBias; 4
WCHAR DaylightName[32]; 32 * 2
SYSTEMTIME DaylightDate; 8 * 2
LONG DaylightBias; 4
} TIME_ZONE_INFORMATION
Total 172 bytes
Now the fun part will be to actually get out the information. There are a number of difficulties.
First the strings are 16 bit Unicode so if you are interested in them you will have to call a different Windows API function WideCharToMultiByte function to convert the 16bit Unicode string into an ASCII string. For this part there has been a post here:
http://forums.ni.com/ni/board/message?board.id=170&message.id=123821&requireLogin=False
For the LONG values you would pick 4 bytes at the appropriate offset from the array through the Array Subset function and then typecast it into an int32 and pass that through the Swap Bytes and Swap Words functions to reverse the LabVIEW Big Endian byte swapping in the Typecast function.
The SYSTEMTIME is a structure with eight 2 byte integers so it would be best to use Array Subset again to extract 16 bytes at the correct offset, typecast this into a cluster with eight int16 numerics and pass it through Swap Bytes too.
You see accessing such API functions in LabVIEW directly can get easily quite a mess and that is the reason why creating a wrapper DLL to convert properly between LabVIEW datatypes and C datatypes gets soon the easier solution if you need to interface with more than one or two functions taking such complicated data structures.
Rolf Kalbermatter
Rolf Kalbermatter
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a division of Test & Measurement Solutions

Problem configuring dll in call library function node

Hi all,
I need help on configuring an external dll into labview. I used import shared library wizard with dll’s header file and got almost all functions (tested, works OK.) except ones with pointer arguments. And I am trying to configure the rest myself. dll belongs to a laser unit to configure, read and save data etc. Definition for one of the functions in the dll is below.
GetCurState(HANDLE hDev, SLOTSELECT SlotSelector, pPOS pposLaser,pPOS pposLsrRes,pPOS pposEncoder,PFLOAT pulBeamStren,PULONG
pulSamples,PTRIGSTAT pTrigstat);
And from documentation
typedef union {
    DOUBLE dPosition;
    LONGLONG llPosition;
    LONG lRawPos;
    } POS, *pPOS;
typedef WORD TRIGSTAT, *PTRIGSTAT;
typedef FLOAT *PFLOAT;
typedef ULONG *PULONG;
I acquire device handle hDev from other function in the dll (and also used them with function with no pointer arguments).
I tried Adapt to Type or Numeric 8-byte double for function parameters and tried wiring numeric, numeric array control and indicator for above parameters in trhe union with no success. Function returns no error but sometimes labview crash.
I read about using union in labview and it was saying to use largest element in size in a union, so I guess the question is what do I wire to a pointer type argument/parameter. For example do I connect a numeric control and indicator to both a pass by Value and pass by Pointer to Value?
Thanks,

Yes, for a union you'd use a datatype that corresponds to the largest element in the union. In you case you had a DOUBLE (64-bits), LONGLONG (64-bits), and LONG (32-bits). Thus, you'd use a 64-bit value, such as DBL control. For the pointer you'd need to use the size of the pointer that the compiler was using. If your DLL is a 32-bit DLL then you'd use a 32-bit integer. If your DLL is a 64-bit DLL then you'd use a 64-bit integer. Note that just because your union has a LONGLONG, it does not necessarily mean you have a 64-bit DLL. For instance, LabVIEW has 64-bit integers, even in the 32-bit version.

LabVIEW PDA reports COREDLL.DLL error when using Call Library Function Node

I'm trying to build a LV PDA app that calls an external DLL file built using embedded visual C. When configuring the Call Library Function node I select the stub DLL, configure the I/O parameters and select OK. When the configuration dialog closes I get the following error:
LabVIEW: LabVIEW.exe - Unable to Locate Component
This application has failed to start because COREDLL.DLL was not found. Re-installing the application may fix this problem.
I do not get this error when using the configuration dialog in the example VIs.
Any suggestions as to the cause and/or the solution?
Thanks,
Ryan

Hello -
When you create a PDA VI that calls a DLL, you must include the .c or .lib file that corresponds to the DLL. Take a look at these documents:
LabVIEW PDA Module Build Errors with VIs that Call DLLs
Why Do I Receive Errors When Calling a C++ DLL from a Call Library Node Using the LabVIEW PDA Module...
How To Call External Code in LabVIEW PDA for Palm OS
H
ow To Call External Code in LabVIEW PDA for Pocket PC
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S Vences
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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

Call a special function in the dll using Call Library Function Node????

Dear all,
I am calling a special function in the dll using call library function node. There is a input parameter that it is a enum type in this function. I don't know how to deal this parameter for calling this function.Has anybody solved this problem?Please advise!
I am appreciated of you anytime.

Most of the times an enum is just a U8/U16/U32, internally so probably you can call it with just a U8/U16/U32 or something. For the correct value you have to look at the definition.
Ton
Free Code Capture Tool! Version 2.1.3 with comments, web-upload, back-save and snippets!
Nederlandse LabVIEW user groep www.lvug.nl
My LabVIEW Ideas
LabVIEW, programming like it should be!

Calling DLL using "Call library function"

I am trying to combine labview with my previous fortran functions using Intel Visual Fortran 12.1 and labview 2012 by below steps.
1. Compile Fortran functions as DLL file.
2. Call Fortran function from LabView via "Call library function"
In step 2, DLL file without linker option "/DLL delayimp.lib" cannot be loaded. That is "delay load" is needed for DLL file.
Are there any limitation or constraint in Call library function?

Hi Vishnu,
There's no problem using the Malloc function in C and call it as a DLL in LabVIEW.
But LabVIEW has a different memory management than C.
It is probably not recommended to allocate array memory in C for labVIEW arrays
You can use initialize array in LabVIEW instead.
Good luck
Van L
NI Applications Engineer

When I use Call Library Function Node in real time, is the DLL loaded once for all or load every time it is called?

When I use Call Library Function Node in real time, is the DLL loaded once for all or load every time when it is called?
I have a time critical real time application, in which I use a piece of DLL function developed by C++. It is OK? Could any senior developer assure me?
Thank you in advance.
Solved!
Go to Solution.

qing_shan61 wrote:
When I use Call Library Function Node in real time, is the DLL loaded once for all or load every time when it is called?
Once
qing_shan61 wrote:
I have a time critical real time application, in which I use a piece of DLL function developed by C++. It is OK?
OK
Be sure that all DLL calls are thread safe (do not perform calls in UI thread).
Also for real-time application you need real-time OS.
Andrey.

Passing Variant to dll using call library function node

Hi,
Using LV2012
I have a dll that the following prototype:
SetTestResult(LPCTSTR Serial, int Test, int Result, VARIANT measuredValue);
How can I pass the Variant to this node when my variant can be either int or float.
I have tried "ToVariant" function but it is not sending data and gets error 1517 on LabView. For configuration parameters for variant I have used ActiveX type and datatype as activeX Variant Pointer.
So for call library function node my prototype looks like this:
int32_t SetTestResult(CStr Serial, int32_t Test, int32_t Result, VARIANT *measuredValue);
Can someone help me understanding What am I doing wrong here please?
Thank you,
Hiren
Hiren Patel

Hello Hiren,
Posting your code (even without the DLL) would definitely make it easier for people to point out potential issues. Here is an example that demonstrates passing an ActiveX variant to a DLL built in CVI, I would suggest cross-checking the way the Call Library Function Node has been configured.
Example:Transferring an ActiveX Reference Pointer to a CVI DLL
http://zone.ni.com/devzone/cda/epd/p/id/3343
Regards,
Tom L.

Using an external DLL with "Call Library Function"

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