The cable required for D-RATS for most radios is the ICOM OPC-1529, or equivalent.  The ID-800H requires a different cable with a mini-DIN connector on the end.  NOTE: the OPC-478 cable is for programming and will not work for data transfers.

The data cables for all the radios are easy to build yourself by following these schematics:

http://www.n5zpr.com/Media/icom_cables.pdf

A ferrite bead on the data cable is recommended, especially for handhelds to prevent RF from corrupting the serial data stream.