PID Control

Calculates PID feedback control. PID stands for Proportional, Integral, and Derivative; the three terms are combined to minimize the error between the setpoint and the measured value. Controllers and their control direction (direct or reverse) are registered in Settings > PID Control (Part 6).

PID Control

Select the PID controller to use.

Commands

• Compute (default): Performs one PID calculation. This command must be repeated at a regular interval.
• Stop: Stops the PID calculation.

Fields

All of the following fields are displayed only when Command is Compute.

Proportional Gain (Kp), Integral Gain (Ki), Derivative Gain (Kd)

Enter the three gains. The default of each is 0.

Setpoint (SP)

Enter the target value the system should reach (for example, the set temperature in temperature control).

Process Variable (PV)

Select the Number variable that holds the measured value (for example, the measured temperature in temperature control).

Control Output (CV)

Select a Number variable to store the calculated control value, the quantity the system must adjust to reach the setpoint (for example, the opening of a boiler valve in temperature control).