Configure buffered data (maximum queued updates)

Buffered data is data captured and stored locally on a remote or a local device for later transfer to a supervisory system for processing, analysis, and long-term storage. The buffered data feature enables efficient accumulation and propagation of VTQ (Value, Time, and Quality) data updates, without folding and data loss. Communication Drivers, such as MQTT, can acquire buffered data from a remote data source.

The Buffered Data (Maximum Queued Updates) sets the maximum number of buffered values that the Communication Driver can accumulate without folding. The minimum value of this parameter is 1, and the maximum value is 1,000. As the unit of Buffered Data (Maximum Queued Updates) is in thousands, if the value of the Buffered Data (Maximum Queued Updates) is 1, then up to 1000 data updates can be buffered per tag. If the value of the Buffered Data (Maximum Queued Updates) is 1000, then up to 1,000,000 data updates can be buffered per tag. When the queued data updates exceed this limit, the newest value replaces the oldest value.

For example:

• Example1: Consider you have set the value of Buffered Data (Maximum Queued Updates) to 1, which is 1000 data updates. If there is a buffered data of 1100 updates that are received by the Communication Driver, then the last 1000 data updates of buffered data will be sent to System Platform for processing and historization, the first 100 data updates of the buffered data will be lost.

• Example2: Consider you have set the value of Buffered Data (Maximum Queued Updates) to 2, which is 2000 data updates. If there is a buffered data of 1100 updates that are received by the Communication Driver, then all the 1100 updates of buffered data will be forwarded to System Platform for processing and historization. There will be no data loss because 1100 updates are below the maximum queued updates value.

For more information on buffered data, refer to the Working with Buffered Data section in the AVEVA™ Application Server User Guide.

Note: The default value of the Buffered Data (Maximum Queued Updates) parameter is 1 (that is, 1000 maximum buffered values) for most Communication Drivers. Some individual Communication Drivers impose a different value that has been documented in the respective section of the Communication Driver.