Danny,
Could you send me a direct e-mail with what you ordered and how you want this all to work? To be able to use the US2 sonar transducer with the 360 Imaging transducer or use the 2D/Si/Di sonar from the HDSi transducer you will need a switch but I don’t know where the y-cable comes into the connections.

Unless you ordered it; you will need one of the AS-EC-QDE Ethernet Adapter Cables to go from the 1199ci HD Si unit and the Ethernet Cable.