Introduction
The SRF06 is a low cost ultrasonic ranger with a 4-20mA current output. The SRF06 is powered from the 4-20mA current loop and requires no other power. Measurement range is from 2cm  to 5.1mtrs. Current output is from 4mA at zero range to 20mA at 5.1mtrs (510cm), which gives a nominal current of 4mA + 31.37uA/cm. The SRF06 requires a loop driving voltage of 9v to 24v. The SRF06 automatically performs continuous ranging every 70-100mS. 

Connections
The SRF06 has only two connections, the positive and negative current loop. An on-board diode protects the module in case of reversed connections.

Converting to a voltage output
Unless you are connecting to a PLC or similar controller with a 4-20mA interface, you are likely to prefer a voltage output. This is very easy to do by sending the current through a resistor. A 250 ohm resistor will have a voltage of 5v across it when 20mA is flowing (at the maximum range of 510cm). If you cannot find a 250 ohm resistor, just put two or more lower values in series to make up 250 ohm. For instance a 100 ohm and 150 ohm, as indicated below. This will give you 1v to 5v for a 4mA to 20mA input.