Azure topic and sending message over MQTT

Question

Is it possible to send messages to azure to any custom topic via mqtt. All example that I've found so far work with standard topics

'devices/' + hubName + '/messages/events/'
'devices/' + hubName + '/messages/devicebound/#'

Btw, I tried to send/subscribe on the topic/subscription above with MQTT.fx application and never received messages, although the connection was successful.

Answer 1

The topic filter of devices/{device_id}/messages/devicebound/# is to subscribe receiving message from IoT Hub(Cloud-To-Device message), it think you need to understand the difference about device-to-cloud message and cloud-to-device message from here. The topic of devices/{device_id}/messages/events/ is for sending a device-to-cloud message from device.

You can use Device Explorer to test this issue. When you send a message to device with the tool, MQTT.fx will receive the message.

Answer 2

Did you have a look on these ??

Azure IoT Hub - Send message (C2D) to one device on 2 topics instead of devicebound/#

Can I send a message to a group of Azure IoT Hub Devices connected via MQTT WebSocket?

https://docs.microsoft.com/en-us/azure/iot-hub/iot-hub-devguide-c2d-guidance