Calling Change Detection Timing event

[Andy_458233]

Hi

Im using LabWindows CVI v8 and Im having problems with calling a function which contains the following standard CVI functions:

DAQmxCfgChangeDetectionTiming

DAQmxRegisterSignalEvent

The problem is I have put these in my own function of type    void functionname (); as shown below:

int CVICALLBACK starttestbutton_callback (int panel, int control, int event,
  void *callbackData, int eventData1, int eventData2)
{  

     switch (event)
      {     case EVENT_LEFT_CLICK:

            function1();

            function2();

            etc
            functioname()

            function3();

            function4();
            break;
 }
 return 0;
}
  

When the function is called by my code, the function is executed but it doesn't work properly as the DAQmxRegisterSignalEvent callback function doesn't get called. However, if I call this function directly from a user interface command button as shown below, it executes fine.

int CVICALLBACK StartCallback(int panel, int control, int event, void *callbackData, int eventData1, int eventData2)
{ 
      if (event==EVENT_LEFT_CLICK)
      {     functionname();
      }
      return 0;
}

Are there some restrictions as to how these standard CVI functions are called?

Any help would be appreciated.

Thanks Andy

Message Edited by Andy_458233 on 03-29-2006 05:02 AM

Message Edited by Andy_458233 on 03-29-2006 05:05 AM

Message Edited by Andy_458233 on 03-29-2006 05:07 AM

[Andy_458233]

I have found a way round the problem by calling my function from within the following if statement which is in the same place as the original function call:

if (event==EVENT_COMMIT)
  {   
        functionname();
  }
  return 0;

It seems like the CVI functions require the return value or to be called by an event before they execute properly.

Message Edited by Andy_458233 on 03-29-2006 06:00 AM