Glossary · Automation fundamentals, platforms and components
Setpoint
Also known as: SP, Reference value, Command value
German: Sollwert
In control engineering, a setpoint (SP) is the desired value of a process variable that a controller tries to reach and maintain. The difference between setpoint and measured process variable is the control error.
- Automation components
In one sentence
A setpoint (SP) is the desired value of a process variable that a controller tries to reach and maintain, such as 80 °C or 1,500 rpm.
Example
The operator raises the oven setpoint from 180 °C to 200 °C, and the temperature controller increases heating power until the PV matches.
How it applies
- Engineering: Setpoints come from operators, recipes or higher-level controllers (cascade). Limits and ramps prevent setpoints that the process cannot follow safely.
- Operation: HMI faceplates show setpoint, Process variable and output together. Changes to critical setpoints are often logged with user and time.
- Documentation: Specify permitted setpoint ranges, units, who may change them and where they are stored (recipe, controller, HMI). Operating manuals should explain what happens if a setpoint is out of range. In GMP environments, setpoint changes can be part of the audit trail.
Setpoint vs. limit
A setpoint is the target value the loop controls to. An alarm or trip limit is a boundary that triggers a warning or protective action when exceeded; it is not a control target.