Hello Paulo ,
In DE4 user Manual link below : 71/159 section : power measurement provide the explanation how to measure the power via FPFA stratix V GX FPGA via ADC converter. Here resistor is the sense reistor , low ohm value R connected series via each power rail nad Voltage across the R sense is equal to current flow through the Rsense . This voltage is read by the ADC and convert to digital data to feed to FPGA.
In the FPGA RTL you can read the Digital data and convert into the voltage value using transfer function given in the ADC part used in the board.
For more details , Kindly go through the schematic of the board.
hope helps ,
Thank you ,