Understanding 2-wire decoder systems
Dave Shoup · Irrigation Australia: The Official Journal of Irrigation Australia · 2014
Decoders are electronic devices that are connected to a wire path from an irrigation controller. They operate irrigation valve solenoids by receiving both signal and power from the same wire path. This allows the installation of many irrigation stations (or valves) down the same wire run, rather than requiring a separate power wire for each solenoid.