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I have been trying to make a simple MQTT pub sub communication on my device using node-red. I have published and subscribed to the topic: telemetry. the server and port used are : mqtt.bosch-iot-hub.com:8883 . For the TLS configuration, the iot hub certificate provided by bosch is being used(https://docs.bosch-iot-hub.com/cert/iothub.crt). I am able to successfully publish the data on the topic and receive it using a HONO receiver. But when I directly subscribe to that topic using node-red mqtt-in node or mosquitto_sub, it doesn't receive the data.

Can someone please help me understand why is it happening and what could be the possible solution to it?

sakshi gupta
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  • May I ask what you are trying to achieve by subscribing to the "telemetry" topic? – Kai Hudalla Dec 19 '19 at 07:21
  • I just wanted to send and receive telemetry data using Bosch Iot Suite using an API. But because i dont have it ready right now that is why i am using node-red. Also I dont have a particular use case in mind. I am exploring the IoT Suite right now so as to understand its working and then work on some use case. – sakshi gupta Dec 19 '19 at 10:06

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There is no point in devices subscribing to the telemetry topic. In Hono (and thus the Bosch IoT Hub) devices only publish telemetry data and/or events. Such data is consumed by downstream applications using Hono's north bound, AMQP 1.0 based Telemetry and Event APIs. Applications can use Hono's AMQP 1.0 based Command & Control API to send commands to (connected) devices. In order to receive commands, MQTT based devices need to subscribe to the command topic.

Kai Hudalla
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