Publishing State

Associated with: Sparkplug Publisher database items

This status attribute indicates the state of the backlog of historic data that the Sparkplug Publisher is to publish to the Primary Host Application.

Possible states:

• Not Publishing / Caching new values—The Sparkplug Publisher is unable to publish historic data to the Primary Host Application. The most likely reason is due to the Primary Host Application being offline. Other possible reasons include the MQTT driver not running, or the Publisher's broker being disconnected from the MQTT broker.

  This state indicates that the Publisher is caching historic data until a healthy connection can be established with the Primary Host Application.

• Publishing Disabled / Caching new values—The Sparkplug Publisher is not publishing historic data to the Primary Host Application because the Historic Data Publishing Enabled check box on the configuration Form of the Sparkplug Publisher is not selected. The check box is clear by default when you create a Sparkplug Publisher database item (see Configure the Properties on the Sparkplug Publisher Tab).

  This state indicates that the Primary Host Application is online and the Sparkplug Publisher has sent birth messages to that Primary Host Application. However, the Publisher is storing (rather than publishing) the historic data. You should enable the Historic Data Publishing Enabled check box on the configuration form of the Sparkplug Publisher once the client database is set up and you want the Publisher to start publishing data.

• Publishing - Backlog still to be published—The Sparkplug Publisher is active, and is in the process of publishing the backlog of historic data to the Primary Host Application.

• Publishing - Up to date—The Sparkplug Publisher is active, and has finished publishing the backlog of historic data to the Primary Host Application. In this state, the Sparkplug Publisher immediately publishes any new historic data values that it receives.