Glossary · System coordination, integration and orchestration
Hierarchical control
Also known as: hierarchical control architecture, layered control
German: Hierarchische Steuerung
In automation architecture, hierarchical control is an approach in which control functions are arranged in levels, such as enterprise, site, area, line or cell and device, where each level coordinates the level below it and reports to the level above, as reflected in the ISA-95 / IEC 62264 models.
- System integration
- Standards
In one sentence
Hierarchical control arranges control in levels, each coordinating the level below it and reporting upward, as reflected in ISA-95.
Example
The MES sends orders to the area controller, the area controller distributes them to line controllers, and each line controller commands its machine PLCs.
How it applies
- Architecture: Hierarchies structure responsibilities and time scales: upper levels plan in hours or days, lower levels react in milliseconds. ISA-95 / IEC 62264 describes the functional levels and the information exchanged between business and manufacturing operations.
- Engineering: Each level must be able to keep the process in a defined state if the level above fails. Commands should flow down and status up; bypassing levels makes behavior hard to reason about.
- Documentation: An overview diagram of the control hierarchy helps every reader, from integrators to operators. Use the same level and equipment names across documents.
Hierarchical control vs. distributed control
Hierarchical control describes vertical levels of authority. Distributed control describes how control is spread horizontally across controllers. Most plants combine both.