Enable buffered data

Buffered data is data captured and stored locally on a remote device for later transfer to a supervisory system for processing, analysis, and long-term storage. The Buffer property is input-only.

Enabling buffered data alters the run-time behavior of some Application Server features such as History and Alarms. Buffering is essential if the Telemetry Server is installed.

Application Server includes the option to enable buffered data for the entire Galaxy by setting the enable auto-buffering configuration option. See Auto-buffering for additional information.

The buffered data feature works identically for both Galaxy-wide and individually-enabled buffering for attributes. In other words, if you have enabled auto-buffering for the Galaxy, the feature works the same as it does when you enable data buffering for individual attributes.

The buffered data feature enables efficient accumulation and propagation of VTQ (Value, Time, and Quality) data updates, without folding and data loss, to data consumers such as objects, alarms, the Historian, and scripts from field devices that support buffering. If the Telemetry Server is used with Application Server, buffering must be enabled to ensure that all data from the Telemetry Server is received by Application Server, and then sent to the Historian in its entirety.

Enabling the buffered data feature preserves all intermediate data values. Thus, if an attribute receives different values during a single scan cycle, the data is not folded or compressed. Data folding occurs when an attribute value changes multiple times within a single scan, and only the latest value is stored. With buffered data enabled, the entire subset of values is propagated to data subscribers such as the alarm subsystem and the Historian, if the attribute is configured to be alarmed or historized. Scripts can also take advantage of processing buffered data. Since the Telemetry Server only sends a data request periodically, and often only once per day, enabling buffered data ensures that Application Server preserves all intermediate data values.

Note: If multiple attributes with I/O enabled are configured for buffered data from the same data point in the Telemetry Server, only one attribute will receive the buffered data at run time.