Buffered data and late data support

As of Communication Drivers Pack 2023, data acquired by the Communication Drivers are buffered based on the received order until they are drained either by the OPC, SuiteLink, or PCS IData client of the Communication Driver. The size of the buffer is determined on a per item basis by the configuration parameter "Buffered Data" in the Global Parameters. Since the memory associated with the buffer is only allocated on a per-demand basis, any spike in memory consumption only occurs temporarily until the buffer is drained by either the OPC, SuiteLink, or PCS IData client of the Communication Driver. Refer to Configure buffered data (maximum queued updates) for configuration details.

If the acquired data in the Communication Driver are out of time sequence consecutively, the quality of subsequent data (that is, late data) will be indicated with the 0x0100 mask.

Consider two consecutive data values received by a Communication Driver:

The value of the first received value chronologically has VTQ:

value 1.0, timestamp 2022-02-28 11:00:00, quality 0x00C0

and the next received value has VTQ:

value 2.0, timestamp 2022-02-28 10:59:00, quality 0x00C0

The first received VTQ will be dispatched to SuiteLink/OPC/PCS IData clients as is but the second received value will be dispatched to SuiteLink/OPC/PCS IData clients with the data quality 0x01C0 since its timestamp (2022-02-28 10:59:00), is earlier than the timestamp of the VTQ immediately preceding it (2022-02-28 11:00:00). This will facilitate System Platform in recognizing and processing late data so that they can be reconstituted in the System Platform Historian in the proper time order in the VTQ.