Upload sketch without USB

I use the code from this project. There are lines

digitalWrite (EnTxPin, HIGH ); //enable to transmit

which indicate that the Tx pin needs to be enabled\ disabled.

got it

i have a rs485-sniffer (link). Is it possible to use it for development purposes?

In the afternoon I have time to test a few setups. Currently I only connected three Nanos via RS485 and the RS485-Sniffer and made a simple protocol to verifiy communication.

I will report back with my attempts.