Originally Posted by
yupitsme
On the Gen3 [Settings]-->[Network]-->[Data Source][Sonar]-->[Temp]-->Data Source. Select Gen3 Transducer temp as source. Of course this assumes that the transducer connected to the Gen3 does in fact have a temp probe. You actually gave us very little info. "I've played with settings for over an hour...." doesn't tell a whole lot.
This also assumes you understand how to add data overlays to a panel.... But it doesn't really sound like you do. Temp data source has nothing to do with networking a transducer that is directly connected to the MFD. Nor does single/multi source.