HDS Gen 2 touch 7 and 9

I'm mounting another HDS7 gen2 in front of my boat already have one, I have a HDS 9 at the drivers seat, I want to read the structure scan transducer from the HDS 9 on the new HDS7, I have the network cable installed, what is if anything to I need to install. Also have point one gps puck mounted and networked to all three units.
Thanks in advance for any suggestions.
onthelakefishin

If you have them hooked together with a Ethernet cable you're good on the structure scan. NMEA 2000 for the external antenna.