Is the Helix 7 G3N or G3 it must have the N to be able to network. The Helix series requires an Ethernet adapter, the Ethernet cable will go directly on the 1197. If all 3 are connected it will require the 5 port Ethernet Switch and Ethernet cables for each unit.
https://humminbird.johnsonoutdoors.c...thernet-switch
https://humminbird.johnsonoutdoors.c...-adapter-cable