modbus with CONTROLLINO mega after modifying a modbus library, see here https://github.com/CONTROLLINO-PLC/CONTROLLINO_Library/issues/36

modbus_controllino_rs485.ino

#include <Controllino.h> 

#include <modbus.h>
#include <modbusDevice.h>
#include <modbusRegBank.h>
#include <modbusSlave.h>

modbusDevice regBank;
modbusSlave slave;

void setup() {
  regBank.setId(1);
 
 pinMode(CONTROLLINO_RS485_TX, OUTPUT);
 pinMode(CONTROLLINO_RS485_RX, INPUT);
 
 pinMode(CONTROLLINO_RS485_nRE, OUTPUT);
 pinMode(CONTROLLINO_RS485_DE, OUTPUT);

  regBank.add(1);
  regBank.add(2);
  regBank.add(3);

  slave._device = &regBank;
  slave.setBaud(19200); 
}

void loop() {

  regBank.set(1, digitalRead(CONTROLLINO_A10));
  regBank.set(2, digitalRead(CONTROLLINO_A11));  

  digitalWrite(CONTROLLINO_D0,regBank.get(3));
  
  slave.run();  

}