4.2.8 MQTT
MQTT is a standard messaging ISO protocol studied for conditions where a low power consumption is
required, and bandwidth is limited.
Protocol implements a mechanism of publication and subscription for messages exchange through a message
broker. Sender publishes the messages about a certain topic on the message broker. The recipient interested
in receiving those messages subscribes to the topics they’re interested to. Every time a new message is
published on that topic, the message broker delivers it to all the recipients.
To enable MQTT on Alpha-Log use the program 3DOM.
First, configure the protocol in the Connectivity section (§4.1.3). In addition to the broker parameters,
activate the publication of the desired messages (instant values, processed values, diagnostic data, alarms).
Then, enable the additional information that will be included in the messages (instrument S/N, latitude,
longitude, altitude, etc.) in the Elaboration Parameters (§4.1.7).
Possible topics to subscribe to are the following:
where:
- <model> is the instrument code (ALP001 or ALP002, §6.1.1).
- <serial> is the instrument serial number (§6.1.1). If 3DOM’s parameters Alternative serial code and
Use an alternative serial code del Registry are set, serial number is set by the user (§4.1.1).
Messages are published with the following logics:
- Instant values: based on MQTT parameter Inst. values publishing time rate (§2.2.6.4).
- Processed data: based on the Elaboration data delivery time rate parameter (§4.1.7).
- Header files: sent before each dispatch of n consecutive Processed data messages.
- Diagnostic data: topic to be implemented.
- Alarms: based on the occurrence of an event.
- Configuration: when a new configuration is applied to the instrument.
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