The 1197 does have Ethernet but an earlier version of it so it has some limitations but connecting to another unit is not one of them.

If the 1197c Si and the 859ci HD are Ethernet connected together, the 859 will not be able to display the Si or DI sonar from the 1197 but it can display the 2D sonar from the 1197 unit: http://www.humminbird.com/Category/S...tSonarSharing/

Now, if you had a 1199ci HD Si unit you would be able to display the Si and Di sonar from the 1199 unit to the 859ci HD unit. Part of the difference between the 1199 and the 1197 (and 1198) units is that you can share more sonar types between units whose model name ends in a “9”.

All 859 units are “HD”.