How to use the Default function for processing actuator commands from the Cayenne Dashboard

Sending MQTT messages to the broker/dashboard works.
But I have no idea how to use the Default function for processing actuator commands from the Cayenne Dashboard.
I want to set an level in my Arduino sketch by a slider from dashboard.

Can you post the code you have so far?

I have uploaded the file ControllinoLight-R.txt (had to change .ino to .txt for download).
Sending works.

Another point: I see the MQTT client in in the WebGUI on my PC but not on my Android.
Second question: How can I subscribe the MQTT messages sent to Cayenne from another Linux device by mosquitto for example. I do not know the topics

So the WebGUI should look like and work.

  Switching Power Plugs dependent of ambient light by CONTROLLINO
  Light Sensor is a photo resitor connected to A1.     |--/\/\/\--|--/\/\/\--- VCC
  Power Plugs are switched by Relais_00 and _01                    A1
  Created by: Claus Kühnel 2017-02-08
#include <Controllino.h>
#include <Wire.h>
#include "Arduino.h"

#define CAYENNE_PRINT Serial
#include <CayenneMQTTEthernet.h>

// Cayenne authentication info. This should be obtained from the Cayenne Dashboard (BYOD).
char username[] = "";
char password[] = "";
char clientID[] = "";

int SWITCH_ON = 200;  // higher values mean more light
int light = 0;
boolean state = false; // false means R0 off

void setup() 
  /* Here we prepare D0, R0, and R1 as output, A1 as input */

  /* Here we initialize serial at 115200 baudrate for reporting */
  while (!Serial); // wait for conecting monitor
  Serial.println("\n\nLight Control MQTT");

  /* If we are using Controllino MEGA, we want to try using non arduino supported pins, so we initialize them */
    /* We need to set direction of all pins to output (1). We are going to use pins PD4(D20), PD5 (D21), PD6(D22) and PJ4(D23) and set them to low*/
    DDRD |= B01110000;
    DDRJ |= B00010000;$
    PORTD &= B10001111;
    PORTJ &= B11101111;
  /* When using Controllino MEGA or MAXI we have access to /OVL pin and RS458 /RE DE pins */
  #if defined(CONTROLLINO_MAXI) || defined(CONTROLLINO_MEGA)
    /* Direction for /RE (PJ5) DE (PJ6) pins is output (1). For /OLV (PE7) its input (0) */
    DDRJ |= B01100000;
    DDRE &= B01111111;
    PORTJ &= B10011111;
    Serial.print("/OVL: "); Serial.println(PINE >> 7);
  // Connect to Cayenne MQTT broker
  Cayenne.begin(username, password, clientID);
  /* Now we report start of application */
  Serial.println("Starting CONTROLLINO application now");

void loop() 
   /* We set digital output D0 to low voltage */
  digitalWrite(CONTROLLINO_D0, HIGH);

  float volt = (5.0 * analogRead(A1) * 100.0) / 1024;
  Serial.print("Res:   "); Serial.println(volt);
  Serial.print("State: "); Serial.println(state);

  if (state == false)
    if (volt < SWITCH_ON) 
      state = !state;
      digitalWrite(CONTROLLINO_RELAY_00, HIGH);
      Serial.println("Lamps on");
      Cayenne.virtualWrite(0, state);
      Cayenne.virtualWrite(1, volt);
  if (state == true)
    if (volt > SWITCH_OFF) 
      state = !state;
      digitalWrite(CONTROLLINO_RELAY_00, LOW);
      Serial.println("Lamps off");
      Cayenne.virtualWrite(0, state);
      Cayenne.virtualWrite(1, volt);
  digitalWrite(CONTROLLINO_D0, LOW);

//Default function for processing actuator commands from the Cayenne Dashboard.
//You can also use functions for specific channels, e.g CAYENNE_IN(1) for channel 1 commands.
  CAYENNE_LOG("CAYENNE_IN_DEFAULT(%u) - %s, %s",, getValue.getId(), getValue.asString());
  //Process message here. If there is an error set an error message using getValue.setError(), e.g getValue.setError("Error message");

I’m try to get a Controllino MAXI to work with Cayenne MQTT but not having any luck with the sample code or yours or ANY ethernet code for that matter! Did you have to modify anything library wise to make it work?