SPX5 communicating to ST70

I discovered from reading threads that is not 100% useable until hooked up properly. Right now it is directly connected and provides depth, tiller control and incorrect heading. Not that I can find no means of doing the commissioning.

I purchased the backbone kit and that is not what I needed. I would like to know precisely what I need to buy to make this work completely together.

Thank you in advance. Deb