Simple Arduino program:

Arduino:
Analog to Digital:
- Test an analog signal on A0
- Read the sensor value(0-1023)
- Map the sensor range (0-1023) to a range of 1-100
- Print the mapped value to the serial port

Unreal Engine: 

- Copy the BP_Arduino_Comm.uasset inside the "Content" folder of your UE Project.
- Change the "Port" number to the correspondent Port of your Arduino Board.
- Play: The values from 0 to 100 will print on your screen.