Solution: VAR itfAlarmConfig: AlarmManager.IAlarmConfiguration; itfAlarmConfig7: AlarmManager.IAlarmConfiguration7; SCRIPT itfAlarmConfig := AlarmGlobals.g_AlarmHandler.GetAlarmConfiguration(0); IF __QUERYINTERFACE(itfAlarmConfig, itfAlarmConfig7) THEN itfAlarmConfig7.ClearHistory(FALSE); END_IF Works perfectly for me.