Hi,
I think this link with an example VI can solve your problem.
http://digital.ni.com/public.nsf/websearch/3FBC5856A4BAACB886256D270001A91F?OpenDocument
Example:
http://sine.ni.com/apps/we/niepd_web_display.DISPLAY_EPD4?p_guid=B123AE0CBA5B111EE034080020E74861&p_node=DZ52054&p_submitted=N&p_rank=&p_answer=&p_source=External
TN