Publish a canned message with a button (e.g. rotator preset)¶
This page shows how to add a publish button to the MQTT applet and use it to send a fixed message to your broker — for example, sending a rotator preset command with a single click.
Open the MQTT applet by clicking the MQTT tray button on the right sidebar.
If you are not already connected, click Settings... to open the MQTT Settings dialog. Configure the broker connection details (Host, Port, User, Password), subscription topics, and publish buttons. Click OK to save.
Click Enable to set it to "On". Wait for the status label to read "Connected".
Click any publish button to send its configured payload to its configured topic immediately. The button is only active while connected.
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.
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.
Message log
Displays received and sent messages. Incoming messages shown as 'topic: value'. Outgoing published messages shown with 'TX' prefix. Capped to 50 entries.
Capped to 50 entries. New in v26.6.3: shows sent messages as 'TX topic: payload'.
Enable (Off/On)
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.
The MQTT applet now uses the application theme manager for its visual appearance. Button text, labels, and the message log automatically follow the current theme's colours instead of using hardcoded colours.
Password is stored in the system keychain and loaded automatically when you first enable the connection. If the keychain password is not yet loaded, the status shows "Waiting for keychain".
Broker connection settings (host, port, credentials, TLS, and subscriptions) are configured in the MQTT Settings dialog (Settings > MQTT...) rather than inline in the applet.
Published button definitions are stored as JSON under MqttButtons and persist across restarts.
Hovering over a button in normal mode shows a tooltip with the configured topic and payload so you can confirm what will be sent before clicking.
Starting in v26.6.3, the message log shows both received and sent published messages. Sent messages appear with a "TX" prefix (e.g., "TX rotator/preset: 45") to distinguish them from incoming messages.
Clicking a publish button does nothing — The applet is not connected. Check that Enable reads "On" and the status label reads "Connected". If it shows an error, verify your broker settings and click Enable to reconnect.
Button is missing after restart — Settings are saved when you confirm the MQTT Settings dialog. If AetherSDR was force-closed, the MqttButtons key may not have been written. Reconfigure the button.
Status shows "Waiting for keychain" — The system keychain has not yet provided the stored password. This usually resolves automatically after a few seconds. If it persists, check your system keychain configuration.