Irritrol TW-D-2 Rain Master Twice 2-Wire 2 Station AC Decoder. Unlike other two-wire systems, Irritrol TW-D-2 Rain Master Twice 2-Wire 2 Station AC Decoder provides a two-way communication link between the controller, decoders and valves. This provides the means for testing and diagnostic capabilities within the two-wire path. The simplicity of the two-wire field installation, coupled with the enhanced capability of Rain Master’s ‘E’ series controllers, sets a new precedent for "Two-Wire" control within the irrigation industry.