Some other program (gps software?) already use port 14. That is why it's not available for it to take.
I have a bu-353 using the usb to seria program that ships with it. It works just fine and is set to port 14. I downloaded Xport and set up up but it only allows me to use port 2,3,15,16,17 and up as inputs. It will not accept port 14 as my input port. Is there an easy fix for that?