OK, to answer my own question....
The code that runs in the second Nano actually *reads* using *Hardware serial* and *writes* using the slimmed down *Software Serial* in the file uart_forward.cpp. The "ah ha!" moment was the seeing in the function "ForwardData (in i2cmeter1.ino) where instead of using SWSerial_Available()>0 he uses Serial.available()>0. And then proceeds to do a recvChar=Serial.read(); (and *not* a SWSerial_Read).? In fact the function SWSerial_Read is never used....? However, SWSerial_Write and SWSerial_Print are used to write the data to the Nextion screen. The definition of the RX_PIN is just an artifact of the slimmed down SoftwareSerial (in uart_forward.cpp) where the SWSerial_Begin initializes both a read and write pin...
I speculate that things were done this way because the hardware serial port on the Nano is shared with the USB? This allows debugging to go out over the Serial console and as long as you don't put anything in the input side of the console, you can use it for Hardware Serial RX and all is well...
Whew!? Learn something new everyday....
73
Mark
AJ6CU
