Glossary · HMI, SCADA and operations
Archive tag
Also known as: Logging tag, Archived tag, Historized tag
German: Archivvariable
In HMI and SCADA systems, an archive tag is a tag whose values are recorded in a data archive at a defined acquisition cycle or on change, so they can be displayed in trends, reported or analyzed later.
- HMI and SCADA
In one sentence
An archive tag is a process tag whose values are recorded in an archive for trends, reports and later analysis.
Example
The oven temperature is configured as an archive tag logged every 5 seconds, so the quality department can review the temperature profile of every batch.
How it applies
- Engineering: Configure acquisition mode (cyclic, on change, with deadband), cycle time, retention period and storage size. Archiving every tag at a high rate fills storage and slows queries; archiving too little leaves gaps for troubleshooting.
- Operation: Trend display screens and reports read from archive tags. Missing values after a restart or communication loss should be visible, not interpolated silently.
- Compliance: In regulated production, archived data can be GMP records; they then need protection against change, a reliable Timestamp and backups (see Data integrity (GxP)).
- Documentation: List archive tags with cycle, deadband, unit and retention in the system documentation; users of the data need to know how it was sampled.
Archive tag vs. historian
An archive tag is one recorded variable within an HMI or SCADA project. A Historian is a dedicated system that stores and serves time-series data from many sources, often at plant or enterprise level.