Glossary · System coordination, integration and orchestration
Supervisory controller
Also known as: Supervisory control system, Master controller
German: Übergeordnete Steuerung
In industrial automation, a supervisory controller is a controller at a higher level of the control hierarchy that sets targets, modes, recipes or commands for subordinate controllers and monitors them, instead of controlling actuators directly.
- System integration
In one sentence
A supervisory controller sets targets, modes or commands for subordinate controllers and monitors them, rather than controlling actuators directly.
Example
A supervisory controller in a water treatment plant sets flow setpoints for the pump station controllers based on tank levels and demand forecasts.
How it applies
- Engineering: Keep the division of labor clear: subordinate controllers remain responsible for their local control loops, sequences and interlocks and must stay in a defined state if the supervisory controller fails.
- Communication: Supervisory commands usually travel over non-deterministic networks. Design subordinate controllers to validate commands and handle communication loss.
- Safety: Safety functions stay at the local level in safety-rated systems; a supervisory controller should not be relied on to perform them.
- Documentation: Describe the control hierarchy, which level decides what, and the behavior on loss of supervision. Operators need to know what continues to work locally when the supervisory level is down.
Supervisory controller vs. SCADA
SCADA (supervisory control and data acquisition) is primarily a system for operators to monitor and command a plant. A supervisory controller may be an automated controller without an operator interface. In practice, SCADA systems often include supervisory control functions.