gns,
Your question is addressed in the thread found through the link below,
http://forums.ni.com/ni/board/message?board.id=110&message.id=1872&requireLogin=False
In the link above there is a link to the tutorial below...
http://zone.ni.com/devzone/conceptd.nsf/webmain/CE87CAF65D7DC07286256B4A006F9641?opendocument
If those links do not solve your problem, these links below might help.
http://digital.ni.com/public.nsf/3efedde4322fef19862567740067f3cc/d400b408d9e2d4aa86256bc3007faa55?OpenDocument
http://digital.ni.com/public.nsf/websearch/7A764019957F0EE886256C730000A188?OpenDocument
If I am completely off base, and the links I provided do not answer
your question, please do not hesistate to reply and I will get you an
answer.
I hope this helps,
Lorne Hengst
Application Engineer
National Instruments