OPC-HDA

OPC Classic Historian historical access.

Definition

OPC HDA functions: ReadRaw (raw historic values), ReadProcessed (aggregated: avg, max, min, total), ReadAtTime (specific timestamp), ReadModified (modified values), Inserts (insert new historical), Updates (modify historical), Annotations. Standard aggregations: 16 types ASYNC (TimeAverage, IntegralOverTime, Min, Max, Total, etc.). Successor: OPC UA Historical Access spec part of OPC UA Companion Specifications.

Origin

OPC HDA 1.0 published 2001 by OPC Foundation ; OPC HDA 1.20 published 2003 ; deprecated in favour of OPC UA Historical Access.

Example in context

A process engineer consults 30-day flow sensor history via OPC HDA ReadProcessed with TimeAverage 1h aggregation, returning 720 points for trending analysis.

Related terms

• OPC DA — other OPC Classic.