Glossary · Automation fundamentals, platforms and components
Control hierarchy
Also known as: Hierarchical control
German: Steuerungshierarchie
In industrial automation, a control hierarchy is the arrangement of control functions in levels, where higher levels set goals, recipes or setpoints and lower levels execute them in real time.
- Automation components
In one sentence
A control hierarchy arranges control functions in levels: higher levels set goals and setpoints, lower levels execute them in real time.
Example
An MES sends a production order to the line controller, which starts the machine sequences, while each drive's controller keeps its axis on position.
How it applies
- Engineering: Hierarchies define which level owns which decision, which reduces conflicts. ISA-88 describes a physical hierarchy from enterprise to control module for batch control; ISA-95 describes functional levels from the process to business planning.
- Operation: Commands flow down and status flows up. When a higher level fails, lower levels must continue safely or reach a defined state.
- Documentation: Describe the hierarchy in the system description, including which level has priority in local and remote operation. This helps operators understand why a command from the HMI may be blocked.
Control hierarchy vs. automation pyramid
The Automation pyramid is a common illustration of IT/OT layers. The control hierarchy describes authority and command flow, which may exist inside a single machine too (line, unit, module, device).