See test result at link:
RS-485 Analog I/O Digital I/O works properly coupled to resistors, however when sensors 4-20mA are coupled didn’t work
A Digital IO adapter does not accept 4 - 20mA Analog signals. You need to use the Analog Adapter for that.
I must have spelled it wrong because we’re using the analog adpatador (XA-Z14-CS5PH-A XBee Analog IO adapter external RPSMA). As the description of this equipment on link (http://www.digi.com/products/wireless-modems-peripherals/wireless-range-extenders-peripherals/xbee-zb-adapters#models)
it could do the conversion but it can not.