SetAsyncTimerAttribute(..... ASYNC_ATTR_INTERVAL....) does not work in CVI 8.5, returns error=-2

Question

Using WindowsCVI version 8.5,  trying to set the time interval ( between 20 to 25sec.) in an ascynchronous timer.  IT DOES NOT WORK!
The following code snippet is from asynctmr.c:
            case ASYNC_ATTR_INTERVAL :
                double doubleInterval = va_arg(parmInfo,double);
                if (doubleInterval >= 0)
                    double      doubleResolution = GetResolution ();
                    CVIUSTEtime interval;
                    if (doubleInterval < doubleResolution)
                        doubleInterval = doubleResolution;
                    ConvertDoubleToTime (doubleInterval, &interval);
                    if (CVIUSTEsettimer (asyncTimerPtr->timer, &interval))    <---this function call always returns a {0}.  Causing...
                        asyncTimerPtr->interval = interval;
                    else
                        error = ASYNC_TIMER_FAIL_ERR;    <-----this error to be returned to the caller.
                else
                    error = ASYNC_INVALID_PARAMETER_ERR;
                break;
The timer is created with an interval of 10.0seconds, which works just fine.  But any attempt to change the original value will not work!
Solved!
Go to Solution.

Answer 1

Thanks again for your help.   I used your suggestion to just create the async timer(s) only as needed, embedding the current interval time in the parameter NewAsyncTimer() call.  This seems to work.  Attached is a code snippet of the Timer creation and Callback.  Notice that the instance of the timer self destructs when its timeout event occurs.  I hope this is OK to do this. 
          if ( ( action == OUTPUT ) || ( action == BOTH ) )
             LaunchOutputTerminals( sys.channel[cidx].output );
             NewTimerID = NewAsyncTimer( TimerPeriod, -1, 0, Output_Timer, NULL );            
             sys.channel[cidx].tmr_id = NewTimerID;
             SetAsyncTimerAttribute( NewTimerID, ASYNC_ATTR_ENABLED, TRUE );
       sys.channel[cidx].saved_state = PresentInputState;  //..save new state
    return( 0 );
int CVICALLBACK Output_Timer( int panel, int control, int event,
                              void *callbackData, int eventData1, int eventData2)
   i32 cidx = 1;
   DebugPrintf( "Output_Timer Callback\n" );
   do
      if ( control == sys.channel[cidx].tmr_id ) break;
   while( ++cidx < 17 );
   switch (event)
      SetAsyncTimerAttribute( control, ASYNC_ATTR_ENABLED, FALSE );
      case EVENT_DISCARD:
         sys.channel[cidx].tmr_id = 0;
         break;
      case EVENT_TIMER_TICK:
         KillOutputTerminals( sys.channel[cidx].output );
         DiscardAsyncTimer( control );
         break;
   return( 0 );