Hi,
There are good examples that show your need.
This is a link to one of them.
http://zone.ni.com/devzone/explprog.nsf/6c163603265406328625682a006ed37d/2c74990a028ccab286256935005d47fc?OpenDocument
I searched in www.ni.com/zone
and typed on the search window.
+analog +output +labview +multiple +channel
I hope you get the solution from this example
Regards,
Blasioz Valenzuela
National Instruments