A two conductor hard wired communications link accepts an actual value of at least one parameter of interest from an environmental sensor in the form of data encoded on the conductors via current modulation. The sensor is mounted in a location remote from an irrigation controller. A circuit connected to the sensor transmits an RF signal representing an actual value of a parameter of interest detected by the sensor. A data relay is connected to the hard wired communication link of the irrigation controller. The data relay includes a receiver that receives the RF signal, and circuitry configured to extract the actual value of the parameter of interest and emulate a predetermined set of physical and protocol properties of the hard wired communication link of the irrigation controller.