Hi Syrine,

Looking at your screenshot, $Topic and $Payload are microflow parameters, not variables that automatically read from the console.

The question is: how is this microflow being called?

In the MQTT Connector, when a message arrives on a subscribed topic, the connector typically invokes a message handler microflow and passes:

Topic (String)

Payload (String)

as input parameters.

So:

$Topic

contains the MQTT topic that received the message, e.g.

sensors/temperature

and

$Payload

contains the message body, e.g.

{"value":25.3}

Your log message:

topic {1} - message {2}

with parameters:

{1} = $Topic

{2} = $Payload

should write something like:

topic sensors/temperature - message {"value":25.3}

to the Mendix Console.

A few things to check:

1. Log node level
   • Set the log node MqttConnector.LogNode (or your custom log node) to Info or Trace in the Console.
2. MQTT subscription
   • Verify that the broker connection is successful.
   • Verify that you subscribed to the correct topic.
3. Message handler microflow
   • Ensure this microflow is actually configured as the callback/action for incoming MQTT messages.
4. Test with MQTT Explorer
   • Publish a test message:
   • Topic: test/topic
   • Payload: Hello Mendix
   • Then see whether your microflow is triggered.

If you can share the Subscribe activity configuration (or the full MQTT microflow), I can tell exactly where $Topic and $Payload are being populated and why nothing is appearing in the console.