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AVEVA Enterprise SCADA

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PubSub inputs that have no publisher

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  • Last UpdatedApr 24, 2025
  • 2 minute read

The Application Calculation Engine (ACE) keeps the ACE Configuration (aceconfig) records with PubSub inputs that have no publishers enabled because it is not predictable when a PubSub topic will be published to. Similarly, if a PubSub topic has no publisher, the record remains enabled because information can be published at any minute; however, execution of an ACE code (acecode) will not happen until data arrives.

When a PubSub input is used, the record is Enabled. However, even though records are enabled, they may not be ready to run. Some reasons the PubSub input can be missing information are:

  • No publisher exists for the topic.

  • The publisher is temporarily lost.

  • PubSub topic has not been recently published to.

Although an aceconfig record with a PubSub input could currently be missing data, the topic can be published to at any time. The record is left enabled, and the ACE waits for the topic to be published to. Acecode will not execute if there is not sufficient information, but the aceconfig records resume execution whenever the information for the PubSub input arrives.

When you are looking at the ACE Summary in easy eXtended Operator Station (ezXOS), the default color of the record will remain green because the record is enabled. However, you will know if the aceconfig record is waiting to execute because a PubSub input is missing data because:

  • The aceconfig record will have a Stale icon on the left side of the display, and the colors will be inverted (green writing on black).

  • The output point will have an Error icon.

    Note: The Stale icon overrides the Error icon. If the aceconfig record has been configured to Update Fresh, the output point will show up as stale.

Alarms are not generated because of missing PubSub input data. However, events are generated for the following circumstances:

  • A publisher that previously existed has been lost for at least one PubSub input.

  • All inputs now have publishers when previously this data was missing for at least one PubSub input.