I suggest you to look at this discussion on CRC:
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=506500000008000000C72B0000&UCATEGORY_0=_46_%24_7_&UCATEGORY_S=0&USEARCHCONTEXT_TIER_0=0&USEARCHCONTEXT_TIER_S=0&USEARCHCONTEXT_QUESTION_0=crc&USEARCHCONTEXT_QUESTION_S=0
Hope this helps
Roberto