PID loop configuration

The LoopPoint component implements a simple PID (Proportional, Integral, Derivative) control loop.

The following terms are used when describing the operation of the LoopPoint component.

Process variable (PV): the controlled process, in other words, the value at the setpoint input, your starting point.
Setpoint (setpt): the target for the process variable. In other words, the value at the setpoint output, your goal.
Setpoint error(ES): the difference between the process variable and the setpoint acted upon by the loop algorithm.
Loop output: the correction signal produced by the loop algorithm. This value should be linked directly or indirectly to the NumericWritable component used to position a proportionally-modulated device, such as a valve or damper, that controls the process variable.
Proportional gain (KP): the value of the property Proportional Constant sets the overall gain of the loop as in this ratio:
KP = Output range / affected process range (sometimes called throttling range)
Throttling range: the amount of process variable change expected as a result of throttling the system between the Minimum Output and Maximum Output.
Bias: the algorithm typically adds this value to the output to correct any offset error in proportional calculations and only as a control pivot output value for when PV = setpt.
Action: defines the direction of the output relative to any setpoint error, where:
- Direct means that the loop output increases when PV increases.
- Reverse means that the loop output increases with PV decreases.
Integral gain (KI): is the value of the property Integral Constant used to set or reset the gain of the loop expressed in repeats per minute. This value reacts to the duration of the setpoint error.
Derivative gain: is the value of the property Derivative Constant used to set the derivative or rate gain of the loop expressed in repeats per minute. This value reacts to the rate of change of the setpoint error providing a dampening effect.

PID loop configuration

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