Raymarine Autohelm ST 30 - Manual (Page 19)

ST30 Compass Installation and Operation Handbook 16
2.7 Power supply & Data Transfer (SeaTalk system)
When the ST30 Compass is part of a SeaTalk system, power and data is
transmitted via the daisy-chain cable or one of the Standard Autohelm
SeaTalk Extension or Interface Cables.
LOCK
COMPASS
LOCK
HEADING
AVERAGE
N
D1808-1
LOCK
COMPASS
LOCK
HEADING
AVERAGE
N
–
+
12v Supply
SeaTalk cable