mod_pid

From Sohatex CRIISTAL Wiki
Jump to: navigation, search

This module provides PID control capabilities.

Description

PIDConfig.png

This is the configuration window for the module, which can be opened by clicking the Control > PID Control Configuration menu item.

The left listbox [1] lists all currently defined PID controllers. It is possible to add [2] or remove [3] controllers. Every controller is identified by its name [4], which can be changed using the rename button [5].

This PID control module uses the academic PID control transfer function. This transfer function has the following time-domain form:

PIDFormula.png

Additionally, the controller implements an integrator anti-windup.

Process Variable, Setpoint and PID Control Output Variable can be set at [6], [7] and [15], respectively. Both the current PV value, SP value and Output Value are displayed at [8], [9] and [14], respectively.

The configuration window also offers the possibility to switch between manual and automatic mode [10]. This means, that in manual mode, only the manual output value [12] is used for the control output, while in automatic mode the PID gains and the spcified controller rate [11] are used to calculate the control output. The output of the controller is limited to minimum/maximum values [13].

[19] shows the currently measured maximum deviations of the process variable from the setpoint and can be reset using the reset button [20].

The graphs on the right show the process variable/setpoint values [16], the difference between them [17] and the resulting control output [18].

Changes are applied and saved immediately.

Please be aware, that changing the PV [6] or SP [7] variable, or changing the PID parameters [11] results in a controller reset (meaning that after such an action the integral and derivative action of the controller are reset to zero).