thanks guys for the info
i will power the device using 12v
so basically i can put a 220 ohm resistor between the plus and minus and then read into an arduino pin on the plus
will the 12v overload the arduino pin ?
No that doesn't sound correct. You wire from negative of 12 (or 24) volt PS to 250 ohm resistor, other end of resistor to negative of transmitter, then from + on transmitter to positive 12vdc on power supply. Then wire arduino ground to power supply ground and finally from the ungrounded end of 250 ohm resistor to an arduino analog input pin.
This creates a current loop for the transmitter to operate and the resistor senses the value of the current loop to measure as a 1-5vdc input voltage for the arduino.