Subscribe to rotator / antenna switch topics

Use the MQTT applet to subscribe to topics published by your rotator controller or antenna switch. Incoming values appear in the message log and, if you prefix a topic with *, as an overlay on the panadapter.

Before you start

• The MQTT applet must be visible. If you do not see it, click the MQTT tray button on the right sidebar to show it.
• Your station MQTT broker must be running and reachable from the machine running AetherSDR.
• If you have not yet configured broker credentials, complete Connect to a station MQTT broker first.

Steps

1. Open the MQTT applet by clicking the MQTT tray button on the right sidebar.
2. In the Host field, confirm the broker hostname or IP address. Default: localhost.
3. In the Port field, confirm the broker port. Default: 1883.
4. If your broker requires authentication, enter values in the User and Pass fields.
5. In the Topics field, enter a comma-separated list of the topics you want to subscribe to. To also show a topic's value as a panadapter overlay, prefix it with *. Example:

   *rotator/pos, *ant/selected, station/log
   

6. If your broker uses TLS, check TLS. The port switches automatically to 8883. If you need a custom CA certificate, enter the file path in CA cert; leave it blank to use the system CA bundle.
7. Click Enable to connect. The button label changes to On and the status label reads Connected in green. All settings are saved at this point.

What each control does

Control	Default	Valid range / notes	Setting key
Host	localhost	Broker hostname or IP	MqttHost
Port	1883	1–65535; auto-switches to 8883 when TLS is enabled	MqttPort
User	(empty)	Optional broker username	MqttUser
Pass	(empty)	Optional broker password; masked	MqttPass
Topics	(empty)	Comma-separated topic list; prefix with * to overlay on panadapter	MqttTopics
TLS	Off	Shows/hides CA cert row; auto-flips port between 1883 and 8883	MqttTls
CA cert	(empty)	Path to CA certificate file; blank uses system CA bundle; visible only when TLS is checked	MqttCaFile
Enable	Off	Connects (On) or disconnects (Off); saves all settings on connect	—
Message log	—	Displays up to the last 50 received messages as topic: value lines	—

Tips

• A topic must be entered without the * prefix to be subscribed to; the * only controls whether the value appears on the panadapter overlay. The subscription itself is always active once you click Enable.
• The message log shows only the last segment of the topic path (after the final /) next to the value, so rotator/pos appears as pos: 180.
• Settings are written to disk only when you click Enable to connect. If you edit the fields and close the applet without connecting, your changes are not saved.

Troubleshooting

• Status label shows an error message instead of "Connected" — The broker is unreachable or credentials are incorrect. Verify the Host, Port, User, and Pass values, then click Enable again.
• Topics field accepts your entries but no messages appear in the log — Confirm that the broker is publishing on exactly those topic strings. MQTT topic matching is case-sensitive.
• TLS checkbox is checked but the CA cert row is not visible — Toggle TLS off and on again to force the row to refresh.
• Port did not switch to 8883 when I checked TLS — The auto-switch only applies when the current port value is exactly 1883. If you entered a custom port, it is preserved.

Related

• Connect to a station MQTT broker
• Overlay an MQTT value on the panadapter (prefix topic with *)
• Enable TLS with a custom CA certificate
• Publish a canned message with a button (e.g. rotator preset)