Irritrol TW-D-1 Rain Master Twice 1 Station 2-Wire Decoder. Unlike other two-wire systems, Irritrol TW-D-1 Rain Master Twice 1 Station 2-Wire 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.