Display the latest value of a subscribed MQTT topic directly on the panadapter, so you can monitor station telemetry (e.g. antenna temperature, rotor position, weather data) while operating.
Open the MQTT applet by clicking the MQTT tray button on the right sidebar.
Click the Enable (Off/On) toggle button to connect to the broker. The button reads "On" and the status label turns green when connected.
Ensure the subscribed topic appears in the message log. A line like antennaTemp: 28.4 confirms data is arriving.
The panadapter overlay updates automatically as messages arrive. Only topics with Display on panadapter checked in their subscription configuration are overlaid.
Connects or disconnects from the broker using settings from MqttSettings. Emits connectRequested / disconnectRequested and saves connection enabled state. Password is loaded from system keychain on first enable. If keychain password is not yet loaded, shows 'Waiting for keychain' status.
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Settings... button
Opens the MQTT Settings dialog (MqttSettingsDialog) for broker connection, subscriptions, and publish button configuration. New in v26.5.3. Replaces the inline Host/Port/User/Pass/TLS/Topics fields.
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Message log
Displays received messages as topic: value lines. Also displays transmitted messages as TX topic: payload lines. Processes antenna alias updates from MQTT.
Capped to 50 entries.
Publish buttons
Click publishes the configured payload to the configured topic via MqttClient::publish. Buttons are configured in the MQTT Settings dialog. Only active while connected. Configured via MqttSettingsDialog Publish Buttons tab.
Only the last value of each display-enabled topic is overlaid. The overlay shows the short topic name (last segment) and the value.
To clear the overlay, disconnect the MQTT client (toggle Enable (Off/On) to "Off").
Transmitted messages appear in the message log with a TX prefix, showing the short topic name and first 80 characters of the payload. This helps confirm that publish buttons are working correctly.
Message log is capped at 50 entries. Older entries are removed automatically when the limit is reached.
Nothing appears on the panadapter — Verify the topic subscription has Display on panadapter enabled in Settings > MQTT... > Subscriptions. Check that the message log shows the topic receiving values.
"Waiting for keychain" status — The MQTT password is stored in your system keychain. If it hasn't been loaded, the connection is deferred. Enter the password in the keychain prompt, or configure the broker connection without a password.