I have a HDS7 GEN1& LSS1& HDS8 GEN2& LMS520C all linked together w nema 2000 & eathernet they work good together ,they share weigh points , the 8 shares sonar w the 520 and the structure scan works w/ both HDS,S if I have both units in share I can see either the front sonar or back sonar. I like my set up and need to learn more that I can do ,mesure things and distance ect. Stan