E80 and E120 conflict

[TickMan]

Hello Chuck
Did sime reaserchon my boat yesterday. Look like E80 is Master, bellow all wires description

E-80
1) Power
2) NMEA 0183
4) Seatalk High Speed
5) VGA out
6) Seatalk Alarm Out

Map Chart is inserted in this Display


E-120
1) Power
2) Seatalk High Speed
3) Seatalk Alarm Out


E-120 has alarm code, want to be a master and I can't switch it to secondary display.

Both dispaly was resetted to factory settings. How to find a problem ?