Long Distance Wired Serial Communication with Arduino using RS485 and CAT Cables

This project establishes reliable long-distance serial communication between two Arduino Nano boards using the RS485 protocol and CAT-6E Ethernet cables. At the heart of the setup are two MAX485 converter modules, which translate standard TTL serial signals from the Arduino Nano into differential voltage signals suitable for long cable runs. Because RS485 uses differential signaling across twisted-pair wires inside the Cat-6E cable, it effectively cancels out electromagnetic interference, allowing data to travel up to 1200 meters. On each end of the communication link, an Arduino Nano processes the incoming or outgoing data. The transmitting Arduino sends messages over serial, which the MAX485 module drives down the Ethernet cable. At the receiving end, the second MAX485 module converts the differential signals back into TTL levels for the receiving Arduino Nano. To display the transmitted or received messages locally, each circuit includes a 16x2 alphanumeric LCD paired with a 10k wiper potentiometer to adjust screen contrast. Breadboards and jumper wires are used to neatly connect all components together. Programming is handled via the Arduino IDE using the LiquidCrystal Library to manage the character displays, while the built-in hardware serial communication handles data transfer between the microcontrollers and their respective transceiver modules.