What are Data Historians?
A data historian is a type of time-series database designed to efficiently collect and store process data from a Supervisory Control and Data Acquisition (SCADA) or automation system. SCADA is a computer-based system for gathering and analyzing real-time data to monitor and control equipment that deals with critical and time-sensitive materials or events. The stored data can then be used to display trends of process data on charts, create reports, or perform data analysis.
Data points are configured for each measured item and assigned a tag name and other attributes. Historians log the data records for these points with a timestamp, a value, and a data quality indicator. The records are stored in a series of secure binary files that allow for fast retrieval of the records1. Organizations use data historians to gather information about the operation of programs to diagnose failures when reliability and uptime are critical. Data historians are most common in data centers and industrial control systems. Data historians can be integrated with a variety of software and solutions such as:
- SCADA systems
- ERP platforms
- Manufacturing process control systems
- CMMS (computerized maintenance management system) solutions
- Manufacturing execution software
- Company information management systems
- ISA100 wireless systems
Data historian records may include2:
- Analog data. Examples of analog data include CPU temperature, fan, and other equipment RPMs, flow rates, fluid levels, and pressure levels.
- Digital readings. Examples of digital readings include valve positions, limit switches, discrete level sensors, and motor status.
- Quality assurance data. Quality assurance data many include process, product, and custom limits.
- Alerts. Alerts may include out-of-limit and return-to-normal signals.
- Aggregate data. Examples of aggregate data include average, standard deviation, process capability, and moving average.
The following are the standard components of a historian system:
- Data collectors. Data collectors interface with data sources such as a PLC, networked devices, OPC servers, files, and other data sources.
- Server software. Server software processes the data from the data collectors, stores the data, and serves the data to client applications. The server software components can also provide other services such as a calculation engine, alarm management, and subsystems to provide context for the data.
- Client applications. Client applications are required for data reporting, charting, and analysis.
1 Comeau, 2021, “Introduction and Optimization of Data Historians”
2 C3.ai, 2023, “Data Historian”