@msmacs
Thanks a lot. This is it.
I tried pins 10, 11, 12 (RX / TX / DE-RE) and it worked.
Problem solved.

@kimot
I rejected AltSoftSerial library because:

1. My shields operate on pins 0 to 5. AltSoftSerial has fixed pins 8,9 for Uno and 46,48 for Mega.
2. I want to keep pins 0 and 1 for debug/controller communication
3. I want to use two RS485 shields on my Mega: one using pins 2,3, and second pins 4,5.

Here you can see the setup I'm talking about:
Zihatec RS485 Multiple busses

@mfalkvidd
I tried removing "define MY_RS485_HWSERIAL" but it didn't help.
My code compiles correctly, but there is no communication.
Hardware setup is identical for both examples, except for the rx/tx pins used.
This is very simple setup: a button connected to Nano+Max485 module, and Mega+Max485 gateway, connected via RS485.

@kimot
I have node_id assigned in my Nano node's code.

@kduino @hek maybe you can help here?

Re: How to use SoftwareSerial Library?

Hi.

Anyone managed to run SoftwareSerial on RS485 gateway?
I tried to do everything according to what is said in the link above, but with no success.

This works (using hardware serial1 of my Mega):

#define MY_RS485
#define MY_RS485_DE_PIN 3
#define MY_RS485_BAUD_RATE 9600
#define MY_RS485_HWSERIAL Serial1
#define MY_GATEWAY_SERIAL
#include <MySensors.h>

void setup(){}

void presentation(){}

void loop(){}

and this one doesn't work (trying to use SoftwareSerial pins 4 and 2)

#define MY_RS485
#define MY_RS485_DE_PIN 3
#define MY_RS485_BAUD_RATE 9600

#include <SoftwareSerial.h>
SoftwareSerial mySerial(4,2); //rx, tx
#define MY_RS485_HWSERIAL 
#define MY_RS485_SWSERIAL mySerial

#define MY_GATEWAY_SERIAL
#include <MySensors.h>

void setup(){}

void presentation(){}

void loop(){}

I also made a change in MyTransportRS485.cpp

before:

#if defined(__linux__)
SerialPort _dev = SerialPort(MY_RS485_HWSERIAL);
#elif defined(MY_RS485_HWSERIAL)
HardwareSerial& _dev = MY_RS485_HWSERIAL;
#else
AltSoftSerial _dev;
#endif

and after:

#if defined(MY_RS485_SWSERIAL)
SoftwareSerial& _dev = MY_RS485_SWSERIAL;
#elif defined(__linux__)
SerialPort _dev = SerialPort(MY_RS485_HWSERIAL);
#elif defined(MY_RS485_HWSERIAL)
HardwareSerial& _dev = MY_RS485_HWSERIAL;
#else
AltSoftSerial _dev;
#endif

What am I doing wrong?
I'm using MySensors 2.3.1 library.