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MQTT Engine provides a mechanism for publishing MQTT Messages from an Ignition script.  This can be useful for general messaging outside of Sparkplug.  For example, one may want to interface to another system that uses MQTT such as when using Custom Namespaces at MQTT Engine. This method allows arbitrary MQTT messages to be published based on events that exist in Ignition.

Note

MQTT Engine must have a client connection to a broker to use the publish mechanism. This is configured here

If MQTT Engine client connection is configured to use Primary Host ID, the client will include an MQTT Will message in its connect message with a topic in the format "spBv1.0/STATE/primary_host_id" and a payload {"online" : false, "timestamp" : 1668114759262}.
When the MQTT Engine client goes off-line, the broker will publish the MQTT Will message LWT on behalf of the client for any non Sparkplug B clients subscribing on this topic.



MQTT Message Publishing via Ignition Script:

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