无法连接到MQTT服务器

Question

I am using knolleary library to connect the Arduino UNO board to MQTT server. For broker I am using test.mosquitto.org (85.119.83.194) but I am not able to connect.

Here is my code:

    /*
 Basic MQTT example 

  - connects to an MQTT server
  - publishes "hello world" to the topic "outTopic"
  - subscribes to the topic "inTopic"
*/

#include <SPI.h>
#include <Ethernet.h>
#include <PubSubClient.h>

// Update these with values suitable for your network.
byte mac[]    = {  0xDE, 0xED, 0xBA, 0xFE, 0xFE, 0xED };
byte server[] = { 10, 2, 63, 123};
byte ip[]     = { 85, 119, 83, 194 };

void callback(char* topic, byte* payload, unsigned int length) {
  // handle message arrived
  Serial.println("Message received");
}

EthernetClient ethClient;
PubSubClient client(server, 1883, callback, ethClient);

void setup()
{
   Ethernet.begin(mac, ip);
   Serial.begin(9600);
   Serial.println("Ethernet Begin");

   if (client.connect("arduinoClient")) {
        Serial.println("Client connected");
        client.subscribe("/notification/turnlighton");
   }
   else{
          Serial.println("Client not connected"); 
   }
}

void loop()
{
  client.loop();
}

client.connect("arduinoClient") return false and "Client not connected" message is printed Serial Monitor.

I am not sure what should be the value of

byte server[] = { 10, 2, 63, 123};

As an alternate I also tried to connect to the Really Simple Message Broker (RSMB) in intranet. Still I get same message.

Can any one help in here?

Thanks in advance

SRS

Answer 1

You have it around the wrong way;

byte server[] is your mqtt server's ip address, in your case test.mosquitto.org (85.119.83.194)

byte ip[] is the static ip address you want the arduino to have on your network.

The other thing to check is that you can connect using a cli client to test.mosquitto.org as it is sometimes down I find.

Have a look at my temperature publishing code, https://github.com/matbor/arduinoTemps2mqtt it might give you a few hints as it was modified from that original example that comes with PubSubClient. In my one I just have the arduino running off DHCP.