Hello RS232 Question, Thank you for contacting National Instruments.
You have a similar post with a different answer at the following link: http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=506500000008000000C0C10000&UCATEGORY_0=_49_%24_6_&UCATEGORY_S=0 Have a great day. Sean C. Applications Engineer National Instruments