I use same type (4 -20 ma) ultrasonic sensor,simply connect the sensor output series to a 250 ohm resistor and the output to micro-controller directly...why 250 ohm? because
4 ma x 250 ohm =1 v
20 ma x 250 ohm =5v
so u get a 0 to 5 volt analog signal to your controller,but make sure that both the sensor and the controller has common power supply ie powering 24 volt and 5 volt s derived from a single power source,thats what i do and i works for me.hope it helps