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CODESYS ControlElement Libraries

Introduction

CODESYS ControlElement Libraries includes the ControlLoopLibrary library which provides parameters for controls, filters, and transfer functions for process control and signal processing.

Product description

The ControlLoopLibrary library includes function blocks for process control. It consists of different elements that are assembled flexibly into a control structure. These include various differentiators and integrators, for which various anti-windup strategies are available. In this way, the structure of the created control can be derived from the selected components. Some transfer functions are also achieved according to this scheme. This library also provides an example for the use of nested object-oriented function blocks.

The library also contains several digital filters that can be used for signal processing. For this purpose, it is necessary to determine the rating parameters yourself.

The following function blocks are included in the library:

. Controls

  • Controller_Base: Abstract base function block for creating individual controls

  • Controller_P: Function block for implementing a P control

  • Controller_PD: Function block for implementing a PD control

  • Controller_PI: Function block for implementing a PI control

  • Controller_PID: Function block for implementing a PID control

. Integrator approximation

  • Integrator_Base: Base function block for creating individual integral approximations

  • Integrator_ParabolicApproximation: Function block for approximating the integral by means of a parabola using the last values

  • Integrator_RectangleApproximation: Function block for approximating the integral by means of a rectangle

  • Integrator_TrapezoidApproximation: Function block for approximating the integral by means of a trapezoid

. Anti-windup strategy

These functions blocks provide different strategies to avoid an overflow of the integrator in case of a prolonged control variance.

  • AntiWindUp_Base: Abstract base function block for creating individual anti-windup strategies

  • AntiWindUp_Clamping: Function block for using an anti-windup strategy that fixes the integrator value to the set maximum

  • AntiWindUp_BackCalculation: Function block for using an anti-windup strategy that decreases the integrator value over time

. Differentiator approximation

  • Differentiator_Base: Abstract base function block for creating individual differentiator approximations

  • Differentiator_BackwardDifference: Function block for linear approximation of the integral using the last value

  • Differentiator_LinearAverageApproximation: Function block for linear approximation of the integral using the last values

  • Differentiator_LinearFourPointApproximation: Function block for linear approximation of the integral using the last values

  • Integrator_ParabolicApproximation: Function block for approximating the differential by means of a parabola using the last values

. Two-point controls

  • BangBangController: Function block for implementing a two-point control

  • BangBangControllerWithTimeHysteresis: Function block for implementing a two-point control with time-based hysteresis

  • BangBangControllerWithValueHysteresis: Function block for implementing a two-point control with value-based hysteresis

. Three-point controls

  • ThreePointController: Function block for implementing a three-point control

  • ThreePointControllerWithValueHysteresis: Function block for implementing a three-point control with value-based modulation

. Filters

  • Controller_Base: Abstract base function block for creating individual filters

  • Filter_FIR: Function block for implementing a finite impulse response filter

  • Filter_IIR: Function block for implementing an infinite impulse response filter

  • Filter_SOS: Function block for implementing a second-order section filter

. PWM generation

  • PWM_CreatorBase: Base function block for creating individual PWM signals

  • PWM_Creator: Function block for creating a PWM signal

  • PWM_Creator_FixedCycle: Function block for creating a PWM signal whose cycle time may differ from the task cycle time

. Transfer functions

  • DT1: Function block for writing a DT1 transfer member. For easier application, a configuration using the Differentiator_LinearAverageApproximation is set as default: DT1_LinearAverage

  • IT1: Function block for writing a IT1 transfer member. For easier application, a configuration using the Integrator_TrapezoidApproximation is set as default: IT1_Trapezoid

  • PT1: Function block for writing a PT1 transfer member. For easier application, a configuration using the Integrator_TrapezoidApproximation is set as default: PT1_Trapezoid

  • PT2: Function block for writing a PT2 transfer member. For easier application, a configuration using two Integrator_TrapezoidApproximation is set as default: PT2_Trapezoid

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