You don't need two full arduino boards, two barebones atmega328p work just as well if your up for a little soldering on a perfboard
Dependingg on the noise of the enviroment regular ttl serial should work If not rs485/232 will definetly work
You don't need two full arduino boards, two barebones atmega328p work just as well if your up for a little soldering on a perfboard
Dependingg on the noise of the enviroment regular ttl serial should work If not rs485/232 will definetly work