Hello Jose,
Thank you for contacting National Instruments.
The following link leads to a discussion thread about hex to ASCII serial communication.
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RNAME=ViewQuestion&HOID=506500000008000000F5440000&ECategory=Instrument+Connectivity.Serial+Interfaces
Please reply to this post if you have some more specific questions.
I hope this helps,
Sean C.
Applications Engineer
National Instruments