ArduinoModbus : Modbus RTU Client class
Start the Modbus RTU client with the specified parameters.
ModbusRTUClient.begin(baudrate);
ModbusRTUClient.begin(baudrate, config);
baudrate - Baud rate to use for serial
config - Config to use for serial (see Serial.begin(...) for more info.) defaults to SERIAL_8N1 if not provided
1 on success, 0 on failure