You MUST connect the RX input to the AVR ICP pin which on an Arduino UNO is digital pin 8. The TX output can be any Arduino pin, but the LocoNet library defaults to digital pin 6 for TX ...
This is a Marklin 6040 Keyboard converted to Loconet. - The original i2c PCB is removed and replaced with an Arduino's and a 16bit i2c MCP23016 port expander. - The PCA9685 handles all the LED's. The ...