Thanks for your comment, yes, you are right about it, it also gives you 2 USB ports, (so from 6 to 8 pins must be for the USB from the existing 18).
In this PDF, http://www.dtresearch.com/support/manuals/WebDT366%20Basic%20Operation%20Guide.pdf
, in page 5 it says it also has Network connectivity (I don't think it means Network using an USB network adapter).
But In my case, I just want to build a surface in which I can leave it charging, I don't find USB ports of any use as orbiter.
Any of you two have a cradle and a polimeter?