Glossary · PID
What is PID controller?
A control algorithm that computes its output from the difference between the setpoint (SP) and the measured value (PV), in three parts: proportional, integral and derivative.
P reacts to the size of the current error, I removes the remaining offset over time, and D anticipates the trend and damps overshoot.
The loop on this site’s home page runs a real PI controller: change the setpoint and watch the valve and the level respond.
Related terms
- Programmable logic controller (PLC)
- An industrial computer built to control machines and processes: it reads sensors and switches, runs the control program, and drives motors and valves, repeatedly and reliably.
- 4-20 mA signal
- The most widely used analogue signal in industrial measurement: 4 mA is the bottom of the range and 20 mA the top, and current, unlike voltage, is not affected by cable length.