What is a Historian?
Technical definition
Process historian – a time-series database optimised for collecting, compressing and storing large volumes of process data (measurements, alarms, events) from control systems, with fast access for trends, analysis and reporting.
In brief
The historian is the facility’s memory. Without it, every disturbance is a mystery and every optimisation a guess.
The Challenge
Process data is often collected – but without structure. Tags are logged under cryptic names without units or context, the storage resolution is wrong for the analysis need and the history is locked in a proprietary format at the SCADA supplier. When the energy or AI project later needs three years of hourly data, it turns out the data either does not exist, cannot be understood or cannot be exported.
HubMind’s Methodology
The historian is a central part of the Engine – but the value is created by the Map: tags must follow the facility’s naming convention and carry metadata (unit, location, function) so the data is self-explanatory. We define the collection strategy per signal type: resolution, compression and retention based on real analysis needs.
Architecturally we advocate open interfaces (OPC UA, MQTT, SQL/REST access) so historical data can be consumed by analytics tools, MES and AI – without being locked to one brand.
Warnings & Pitfalls
The log-everything trap: Storing every tag at full resolution forever is expensive and pointless. Collection strategy before installation.
Locked-in history: If the data can only be read with the supplier’s tools, your operational history is part of their business model – vendor lock-in.
Tags without context: A trend named AI4711 without unit and location is archaeology, not analysis.
💡Our Recommendation
Structure the tags: Naming convention and metadata before collection starts.
Collection strategy per signal type: Resolution and retention based on analysis needs – not defaults.
Require open access: The history must be consumable via standard interfaces and exportable in open formats.
Own your memory: Operational history is an asset that belongs to you – write it into the contract.
FAQ
Historian or a general time-series database (InfluxDB, TimescaleDB)? Classic historians offer ready-made control system connectors and proven compression; open time-series databases give flexibility and lower licence cost. The choice depends on integration needs and internal skills – the structural requirements are the same.
Where does a historian sit in the architecture? Classically at level 3 (production-near), often with aggregation upwards. In modern architectures it is complemented by a UNS for real-time sharing.
Can your facility remember what happened last week?
HubMind helps you build structured process history with open interfaces – the foundation for analysis, optimisation and AI.