Slowest OPC UA Rate That Preserves Process Behavior Is Right
Global – October 27, 2026 -- The right OPC UA collection rate is the slowest configuration that still preserves the process behavior needed for operations and historical analysis, and it is set across five separate stages rather than one "scan rate." Device updates, server sampling, subscription publishing, filtering and historian storage each have their own timing. Treating them as one setting can add load without adding information, or hide a pressure transient the historian was expected to explain.
Server sampling cannot beat the source update rate
A PLC may update a temperature every 500 milliseconds while the OPC UA server refreshes its internal value once per second. A client request to sample every 100 milliseconds then re-reads the same value or detects changes no sooner than the server exposes them.