MQTT and the O3

The O3 currently supports the MQTT v3.1.1 specification.

The MQTT topics associated with the can be used to subscribe to data from the O3's internal Eclipse Mosquitto™ broker and send commands to change the O3's setpoints and outputs.

Topic Format

The O3's sensor and device properties are represented by BACnet objects, which are mapped to MQTT topics through an internal BACnet-to-MQTT bridge. The MQTT topics are divided into "events" topics and "commands" topics, indicating the direction of the message. "Events" topics (events/object/SUBTOPIC) are used to report BACnet object values (from sensors, outputs, etc.), while "commands" topics (commands/object/SUBTOPIC) are used to set BACnet object values.

To learn more about the BACnet objects associated with the O3, refer to the BACnet Application Guide.

Setting up EnOcean Devices

The O3 supports up to 32 EnOcean wireless devices. To access EnOcean objects, you must first create a device SV object for each EnOcean device you want to configure. After which you can set EnOcean as your gateway mapping for each device, and then associate a mapping file with each SV object. For more information on setting up EnOcean devices using enteliWEB, refer to the O3 Edge EnOcean Application Guide.

After you've configured your objects in enteliWEB, you can then use MQTT to read and write EnOcean objects. For more information, refer to Using MQTT With EnOcean Devices.

Message Format

The O3 supports key-value content in JSON (JavaScript Object Notation) format as follows:

{"key1": "value1"}

The key is always a string, while the value can be either a string, number, boolean, object, array, or null. Spaces before or after the colon are optional, as JSON ignores whitespace between elements.

For example, the events/object/occupantTemperature topic looks like this:

{"Present_Value": 24.51,"Units": "°C","updated": "31-08-2021 23:09:26.21","status": 0}

Frequently Asked Questions

What MQTT Brokers can be used with the O3? Can I use Google Cloud, AWS or Azure?

Out of the box, the O3 does not directly integrate with external MQTT brokers. Its internal MQTT broker can be used to allow other systems to directly communicate with the O3. Additionally, Node-RED can be used to establish a connection to an external MQTT broker and configure how the O3 data should be transmitted. 

I’m not using MQTT, how do I turn it off?

Starting in firmware 2.0, the MQTT broker will be disabled by default. Refer to Provisioning using Proviso and Provisioning using enteliWEB/enteliCLOUD for details on enabling access.

Can I create my own MQTT topics?

You can register additional objects, but custom topics are otherwise not supported.