Check out the following document
herehttp://zone.ni.com/devzone/conceptd.nsf/webmain/C83E9B93DE714DB08625686600704DB1?OpenDocument
There is a similar reference
herehttp://zone.ni.com/devzone%5Cconceptd.nsf/webmain/2D5849B3108E416B86256DA2007A8E7B?opendocument