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Configuring history on tags indirectly referencing MQTT Engine tags will work properly if the referencing tag is a Reference tag only. Derived, Expression and OPC tags (expose MQTT Engine tag provider through OPCUA server) will not properly store history when MQTT Engine tags are updated with historical data at a high rate of speed. This is a limitation within the Ignition platform and may be addressed in a future release.

If using an Ignition release before v8.1.4 - In order for historical tag changes at the MQTT Engine tag to propagate to the referencing tag, MQTT Engine must be configured to write historical data directly to its tags and MQTT Transmission must be configured to flush history in-order. See this section above for more details on these configuration requirements.

If using an Ignition v8.1.4 or later - Historical back-fill support was added which allows Reference Tags in Ignition to be updated even if history arrives out of order. See the following document for details: MQTT History Back-Fill with Reference Tags

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