For Experts: Why does LabView cause System reboot while accessing hardware with driver?

[ACiDuser]

Hello NI Developers!

I use LabView 7.1 under Windows XP

I have a programm console application which accesses through Jungo Windriver PCI-E board.

This program works fine - and performs DMA data transfer between PC and Board's memory.

In order to implement this console application work together with LabView I did following:

1) Added this function inside the source:

 _declspec(dllexport) void LVMainFunction(uInt32 *IntValue);

_declspec(dllexport) void LVMainFunction(uInt32 *IntValue)
    {

    AllocConsole();                   //Open new console window
    SetConsoleTitle(L"Debug Window"); //Set a title for console window

    freopen("CONOUT$","a+",stdout); //redirec standard output stream to current window so

                                    // so we are able to see "printf" outputs

   freopen("CONIN$","a+",stdin);    //redirec standard input stream to current window so
                                    // so we are able pass inputs from keyboard

   main();                          //Call applications main function which does all the work
}

2) Compiled this new source as DLL library

3) Call  LVMainFunction(...) function from LabView using Call Library Node

In the result: Executing VI - opens new console window, shows debug outputs and receives keyboard inputs.

It works fine till the last function, which perform DMA data transfer - and reboots PC.

1) Why does this happen?

2) I understand that opening console from Call Library Node, attaches together this console window and running VI. So If I close one of them - both windows closes.

     So does LabView have somekind of restrictions of accessing Hardware's functions? 

I can read Board's resource information and view size of memory on board, interrupt functions and other information about device, but when I try to reach

DMA my system reboots. And I understand that this should be some kind of LabView problem, cause I tried different implementations, even without use of

console window - and the result is the same.

3) Should I split the program in to two separate processes and perform data exchange using Sockets or Pipes techology?

Thank you in advance!

ACiDUser

Message Edited by ACiDuser on 11-13-2008 09:37 AM

[ACiDuser]

Hello!

At LAST!!!

I solved this problem!

From the beginning I was following National Instruments manual on how to build DLL with external IDE:

  http://zone.ni.com/reference/en-XX/help/371361A-01/lvhowto/building_library_project/ 

• Set the Struct member alignment control to 1 Byte.
•  
•  
• Now this option caused my PC to reboot!
•  
• So could someone explain  why this happened? and If it is a bad tip, so it's better to remove from manual. Then other people will not have such problems as I did
• - wasting 2 monthes of time determining the problem. 
•  
• I changed it to  Set the Struct member alignment control to DEFAULT.
• and now everything works fine.
•  
• Regards

Message Edited by ACiDuser on 11-13-2008 11:14 AM

[Andrey_Dmitriev]

Hi, ACiDuser,

you wrote:

>So could someone explain  why this happened? and If it is a bad tip, so it's better to remove from manual.

Please take a look to this topic:

http://forums.ni.com/ni/board/message?board.id=170&message.id=363889#M363889

Here explained why and where alignment should be set to 1 byte

another example with good explanation:

http://forums.lavag.org/LV-to-DLL-endian-conversion-question-t12229.html&p=53440#entry53440

best regards,

Andrey. 

[ACiDuser]

Hi!

I have read those topics, but It is still unclear for me.

I did not use any arrays in my code. The VC++ parameter Struct Member alignment was set to 1. It is a recommendation from NI manual.

In those topics were described situataions, when User forgot to set  Struct Member alignment to 1 and recommended to use #pragma pack(1) before and #pragma pack()

after declaration of LabView typedefs. I think my case is different.

Thank you.

[Andrey_Dmitriev]

Hi, ACiDuser,

As you can see, alignment to 1 byte boundary required when you need to pass structures from DLL to LabVIEW (refer to LV memory organization). So, such alignment required not for every DLL. I guess, that NI wrote "Set the Struct member alignment control to 1 Byte" for some kind of "safety" - so this guaranteed that all structures will be passed correctly. But this alignment may affect other parts of code, of course (what exactly happened in your case).

Personally I always using "local" alignment changes with #pragma pack instead of "global" changes with compiler settings.

Andrey.