This feature allows the control of the MQTT Engine client connect and STATE message publish based on the state of one or more Ignition tags. This can be useful if you have multiple services at a Central Gateway, such as MQTT Engine and Cloud Injectors, that all need to online before any Edge data should be sent. 

The configuration for the Primary Host Control utilizes Primary Host Control Tags. MQTT Engine will "scan" these control tags every two seconds and if they have a good Quality and their value matches the defined value configured, the MQTT Engine client will then connect to its defined MQTT Server(s) and publish its STATE message.

If the Primary Host control tag evaluation fails, the MQTT Engine client will not connect to its defined MQTT Server(s) or will disconnect from its defined MQTT Server(s) if already connected.

Available in MQTT Engine module version 4.0.11+


The configuration is available under the General tab in the Main section.

  • Primary Host Control Tags
    • A semicolon separated list of comma separated Primary Host Control tags triples (e.g., tagPath1,tagDataType1,tagValue1;tagPath2,tagDataType2,tagValue2).
    • Supported tag DataTypes are: Byte, Short, Integer, Long, Float, Double, Boolean and String

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