Software serial option - will need 2nd USB/Serial adapter, use 2nd serial monitor program on the PC with different COM port (2nd instance of the IDE even).
Connect Gnd, Rx, Tx. Board should get power from PC.
Software serial option - will need 2nd USB/Serial adapter, use 2nd serial monitor program on the PC with different COM port (2nd instance of the IDE even).
Connect Gnd, Rx, Tx. Board should get power from PC.