detecting DIO task finished

Hi 

How do I know that the externally triggered DIO output of finite samples have finished the execution? 

I see there is a "DAQmx Is Task Done?", but it means I need to constantly monitor the task. Is there a way to generate an event or notifier that the task has finished? 

Aslo, if I use the "Start.Reftrggerable" properly and the task arms iteself after it fires, how do I know how many times the task has finished, i.e. the same question as above, how to know exactly if the task is done and not miss any of the events?

thank you