PidAutotuner.xml

<?xml version="1.0" encoding="utf-8"?>
<project xmlns="http://www.plcopen.org/xml/tc6_0200">
  <fileHeader companyName="Beckhoff Automation GmbH" productName="TwinCAT PLC Control" productVersion="3.5.10.30" creationDateTime="2019-01-29T12:52:46.8644598" />
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  <types>
    <dataTypes>
      <dataType name="E_PIDOptimizationStage">
        <baseType>
          <enum>
            <values>
              <value name="Init" />
              <value name="RampingUp" />
              <value name="RampingDown" />
              <value name="Done" />
            </values>
          </enum>
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{attribute 'strict'}
TYPE E_PIDOptimizationStage :
(
	Init,
	RampingUp,
	RampingDown,
	Done
);
END_TYPE
</xhtml>
            </InterfaceAsPlainText>
          </data>
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      </dataType>
      <dataType name="E_PIDOptimizationType">
        <baseType>
          <enum>
            <values>
              <value name="NoOvershoot" />
              <value name="SomeOvershoot" />
              <value name="PessenIntegralRule" />
            </values>
          </enum>
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{attribute 'strict'}
TYPE E_PIDOptimizationType :
(
	NoOvershoot,
	SomeOvershoot,
	PessenIntegralRule
);
END_TYPE
</xhtml>
            </InterfaceAsPlainText>
          </data>
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    <pous>
      <pou name="FB_MovingAverageReal" pouType="functionBlock">
        <interface>
          <inputVars>
            <variable name="ValueToAdd">
              <type>
                <LREAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Value to add to the moving average.</xhtml>
              </documentation>
            </variable>
            <variable name="NumValuesToUse">
              <type>
                <UINT />
              </type>
              <initialValue>
                <simpleValue value="ANY_TO_UINT(((UPPER_BOUND(AverageArray, 1) - LOWER_BOUND(AverageArray, 1)) + 1))" />
              </initialValue>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> The number of values to store in the array.</xhtml>
              </documentation>
            </variable>
            <variable name="AverageArray">
              <type>
                <pointer>
                  <baseType>
                    <LREAL />
                  </baseType>
                </pointer>
              </type>
              <addData>
                <data name="http://www.3s-software.com/plcopenxml/attributes" handleUnknown="implementation">
                  <Attributes>
                    <Attribute Name="variable_length_array" />
                    <Attribute Name="Dimensions" Value="1" />
                  </Attributes>
                </data>
              </addData>
            </variable>
          </inputVars>
          <outputVars>
            <variable name="CurrentValue">
              <type>
                <LREAL />
              </type>
            </variable>
          </outputVars>
          <localVars>
            <variable name="CurrentIndex">
              <type>
                <UINT />
              </type>
            </variable>
            <variable name="NumValuesAdded">
              <type>
                <UINT />
              </type>
            </variable>
          </localVars>
          <tempVars>
            <variable name="Counted">
              <type>
                <UINT />
              </type>
            </variable>
            <variable name="I">
              <type>
                <DINT />
              </type>
            </variable>
            <variable name="Sum">
              <type>
                <LREAL />
              </type>
            </variable>
            <variable name="ArrayLength">
              <type>
                <UINT />
              </type>
              <initialValue>
                <simpleValue value="ANY_TO_UINT(((UPPER_BOUND(AverageArray, 1) - LOWER_BOUND(AverageArray, 1)) + 1))" />
              </initialValue>
            </variable>
          </tempVars>
        </interface>
        <body>
          <ST>
            <xhtml xmlns="http://www.w3.org/1999/xhtml">// Compute average over array.
// The order of this addition and MOD are important to avoid going out of bounds.
NumValuesToUse := MIN(ArrayLength, NumValuesToUse);
AverageArray[CurrentIndex] := ValueToAdd;
CurrentIndex := CurrentIndex + 1;
CurrentIndex := CurrentIndex MOD NumValuesToUse;
NumValuesAdded := MIN(NumValuesAdded + 1 , NumValuesToUse);
IF NumValuesAdded &gt; 0 THEN
	FOR I := LOWER_BOUND(AverageArray, 1) TO UPPER_BOUND(AverageArray, 1) BY 1 DO
		Sum := Sum + AverageArray[I];
		Counted := Counted + 1;
		// Don't count more than the number of values.
		IF Counted &gt; NumValuesAdded THEN
			EXIT;
		END_IF
	END_FOR
END_IF
CurrentValue := TO_REAL(Sum / NumValuesAdded);</xhtml>
          </ST>
        </body>
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              <xhtml xmlns="http://www.w3.org/1999/xhtml">FUNCTION_BLOCK FB_MovingAverageReal
VAR_INPUT
	// Value to add to the moving average.
	ValueToAdd : LREAL;
	// The number of values to store in the array.
	NumValuesToUse : UINT := TO_UINT(UPPER_BOUND(AverageArray, 1) - LOWER_BOUND(AverageArray, 1) + 1);
END_VAR
VAR_IN_OUT
	AverageArray  : ARRAY [*] OF LREAL;
END_VAR
VAR_OUTPUT
	CurrentValue : LREAL;
END_VAR
VAR
	CurrentIndex : UINT;
	NumValuesAdded: UINT;
END_VAR
VAR_TEMP
	Counted : UINT;
	I: DINT;
	Sum: LREAL;
	ArrayLength : UINT := TO_UINT(UPPER_BOUND(AverageArray, 1) - LOWER_BOUND(AverageArray, 1) + 1);
END_VAR</xhtml>
            </InterfaceAsPlainText>
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            <ObjectId>fda7e211-5c6c-492f-ac36-81cea3ee5c49</ObjectId>
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      </pou>
      <pou name="FB_FreqMeasure" pouType="functionBlock">
        <interface>
          <inputVars>
            <variable name="IN">
              <type>
                <BOOL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Input signal</xhtml>
              </documentation>
            </variable>
            <variable name="PERIODS">
              <type>
                <UINT />
              </type>
              <initialValue>
                <simpleValue value="1" />
              </initialValue>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Number of periods to average the frequency over.
 Must be between 1 and 100</xhtml>
              </documentation>
            </variable>
            <variable name="RESET">
              <type>
                <BOOL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Reset all parameters to 0</xhtml>
              </documentation>
            </variable>
          </inputVars>
          <outputVars>
            <variable name="OUT">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Frequency in HZ</xhtml>
              </documentation>
            </variable>
            <variable name="VALID">
              <type>
                <BOOL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> FALSE until we've measured at least PERIODS periods, or if distance between two rising edges is &gt; 3 * OUT</xhtml>
              </documentation>
            </variable>
          </outputVars>
          <localVars>
            <variable name="RisingEnableEdge">
              <type>
                <derived name="R_TRIG" />
              </type>
            </variable>
            <variable name="FallingEnableEdge">
              <type>
                <derived name="F_TRIG" />
              </type>
            </variable>
            <variable name="STARTED">
              <type>
                <BOOL />
              </type>
            </variable>
            <variable name="RISETIME">
              <type>
                <TIME />
              </type>
            </variable>
            <variable name="AveragePeriod">
              <type>
                <derived name="FB_MovingAverageReal" />
              </type>
            </variable>
            <variable name="DIFF">
              <type>
                <DINT />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Difference in time between current and last rising edge</xhtml>
              </documentation>
            </variable>
            <variable name="TIMEDIFF">
              <type>
                <array>
                  <dimension lower="0" upper="99" />
                  <baseType>
                    <LREAL />
                  </baseType>
                </array>
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Array of time differences for each period</xhtml>
              </documentation>
            </variable>
            <variable name="COUNT">
              <type>
                <UINT />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> How many periods we have counted so far</xhtml>
              </documentation>
            </variable>
            <variable name="SYSTIMEMS">
              <type>
                <TIME />
              </type>
            </variable>
          </localVars>
          <tempVars>
            <variable name="OutTemp">
              <type>
                <LREAL />
              </type>
            </variable>
          </tempVars>
          <documentation>
            <xhtml xmlns="http://www.w3.org/1999/xhtml"> This function is the equivalent of FREQ_MEASURE from codesys's utility library.
   It emulates their wacky API that tries to auto-detect specific errors </xhtml>
          </documentation>
        </interface>
        <body>
          <ST>
            <xhtml xmlns="http://www.w3.org/1999/xhtml">
IF Reset THEN
    VALID := FALSE;
    COUNT := 0;
    STARTED := FALSE;
    OUT := 0;
    RETURN;
END_IF

RisingEnableEdge(CLK := IN);
FallingEnableEdge(CLK := IN);

(* We care only about whether we are the beginning or the end of the signal.
   If we are at the beginning, we store the current time the signal rose.
   If we are the end, we look at the current time, subtract the rise time,
   and add the signal time period to the period array.
   Once we have collected the requested number of periods, we start averaging
   and mark ourselves valid. *)
IF RisingEnableEdge.Q OR FallingEnableEdge.Q THEN
	// The tming mechanism depends on the PLC. What we expect is something that produces milliseconds.
	// The only requirement is that the difference between the two times represent the signal period in millliseconds
	SYSTIMEMS := ULINT_TO_TIME(F_GetTaskTime() / TC2_Utilities.SYSTEMTIME_TICKSPERMSEC64);
    IF FallingEnableEdge.Q AND STARTED THEN
		DIFF := TIME_TO_DINT(SYSTIMEMS - RISETIME);
		// We assume time never goes backwards for real. Unfortunately, the API of this call does
		// not give us a way to express errors easily.
        IF Diff &gt; 0 THEN
			// Emulate the weird behavior of CODESYS FREQ_MEASURE
			IF VALID AND Diff &gt; 3000 * REAL_TO_DINT(OUT) THEN
				VALID := FALSE;
				COUNT := 0;
				RETURN;
			END_IF
			// Compute moving average over periods
			AveragePeriod(ValueToAdd := DINT_TO_REAL(DIFF),
						  AverageArray := TIMEDIFF,
						  NumValuesToUse := PERIODS,
						  CurrentValue =&gt; OutTemp);
			Out := LREAL_TO_REAL (OutTemp); 
            COUNT := MIN(COUNT + 1, PERIODS);
			// Go valid once we have the minimum number of periods to average over.
            VALID := COUNT = PERIODS;
        END_IF
		STARTED := FALSE;
		RETURN;
    END_IF
    STARTED := TRUE;
    RISETIME := SYSTIMEMS;
END_IF

</xhtml>
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              <xhtml xmlns="http://www.w3.org/1999/xhtml">(* This function is the equivalent of FREQ_MEASURE from codesys's utility library.
   It emulates their wacky API that tries to auto-detect specific errors *)
FUNCTION_BLOCK FB_FreqMeasure
VAR_INPUT
	// Input signal
    IN: BOOL;
	// Number of periods to average the frequency over.
	// Must be between 1 and 100
    PERIODS: UINT := 1;
	// Reset all parameters to 0
    RESET: BOOL;
END_VAR
VAR_OUTPUT
	// Frequency in HZ
    OUT: REAL;
	// FALSE until we've measured at least PERIODS periods, or if distance between two rising edges is &gt; 3 * OUT
    VALID: BOOL;
END_VAR
VAR
	RisingEnableEdge: R_TRIG;
	FallingEnableEdge : F_TRIG;
    STARTED: BOOL;
    RISETIME: TIME;
	AveragePeriod : FB_MovingAverageReal;
	// Difference in time between current and last rising edge
    DIFF: DINT;
	// Array of time differences for each period
    TIMEDIFF: ARRAY[0..99] OF LREAL;
	// How many periods we have counted so far
    COUNT: UINT;
	SYSTIMEMS : TIME;          
END_VAR
VAR_TEMP
	OutTemp : LREAL;
END_VAR</xhtml>
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            <ObjectId>3d6d3d65-e18a-4fc3-a773-f23be8247d43</ObjectId>
          </data>
        </addData>
      </pou>
      <pou name="FB_OptimizePID" pouType="functionBlock">
        <interface>
          <inputVars>
            <variable name="Enable">
              <type>
                <BOOL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Starts the sequence on the rising edge</xhtml>
              </documentation>
            </variable>
            <variable name="ProcessSetpoint">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Set point </xhtml>
              </documentation>
            </variable>
            <variable name="ProcessValue">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Process measurement </xhtml>
              </documentation>
            </variable>
            <variable name="NumCycles">
              <type>
                <INT />
              </type>
              <initialValue>
                <simpleValue value="2" />
              </initialValue>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Number of automatic adjustment cycles (minimum 2) </xhtml>
              </documentation>
            </variable>
            <variable name="Reset">
              <type>
                <BOOL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Reset</xhtml>
              </documentation>
            </variable>
            <variable name="ControlLowVal">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Low value for the square wave output</xhtml>
              </documentation>
            </variable>
            <variable name="ControlHighVal">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> High value for the square wave output</xhtml>
              </documentation>
            </variable>
            <variable name="PIDType">
              <type>
                <derived name="E_PIDOptimizationType" />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> PID constants to use</xhtml>
              </documentation>
            </variable>
          </inputVars>
          <outputVars>
            <variable name="TuningDone">
              <type>
                <BOOL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> End sequence</xhtml>
              </documentation>
            </variable>
            <variable name="ControlValue">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Square wave output for the exitation of the process</xhtml>
              </documentation>
            </variable>
            <variable name="Kp">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Proportional gain</xhtml>
              </documentation>
            </variable>
            <variable name="Ki">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Integral time in S</xhtml>
              </documentation>
            </variable>
            <variable name="Kd">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Derivative time in s</xhtml>
              </documentation>
            </variable>
            <variable name="Ku">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Ultimate Gain </xhtml>
              </documentation>
            </variable>
            <variable name="Tu">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Ultimate Period</xhtml>
              </documentation>
            </variable>
          </outputVars>
          <localVars>
            <variable name="rTrigEnable">
              <type>
                <derived name="R_TRIG" />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Enable trigger</xhtml>
              </documentation>
            </variable>
            <variable name="b">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Amplitude of process variable</xhtml>
              </documentation>
            </variable>
            <variable name="a">
              <type>
                <REAL />
              </type>
              <documentation>
                <xhtml xmlns="http://www.w3.org/1999/xhtml"> Amplitude of control variable</xhtml>
              </documentation>
            </variable>
            <variable name="TuFreq">
              <type>
                <derived name="FB_FreqMeasure" />
              </type>
            </variable>
            <variable name="b_Min">
              <type>
                <REAL />
              </type>
            </variable>
            <variable name="b_Max">
              <type>
                <REAL />
              </type>
            </variable>
            <variable name="EndTrigger">
              <type>
                <derived name="R_TRIG" />
              </type>
            </variable>
            <variable name="TuningSequence">
              <type>
                <derived name="E_PIDOptimizationStage" />
              </type>
            </variable>
            <variable name="CycleNumber">
              <type>
                <INT />
              </type>
            </variable>
          </localVars>
          <localVars constant="true">
            <variable name="PI">
              <type>
                <REAL />
              </type>
              <initialValue>
                <simpleValue value="REAL#3.1415926535897931" />
              </initialValue>
            </variable>
            <variable name="REAL_MAX">
              <type>
                <REAL />
              </type>
              <initialValue>
                <simpleValue value="3.402823E+38" />
              </initialValue>
            </variable>
            <variable name="REAL_MIN">
              <type>
                <REAL />
              </type>
              <initialValue>
                <simpleValue value="-3.402823E+38" />
              </initialValue>
            </variable>
          </localVars>
        </interface>
        <body>
          <ST>
            <xhtml xmlns="http://www.w3.org/1999/xhtml">
IF Reset THEN
    TuningSequence := E_PIDOptimizationStage.Init;
	TuningDone := FALSE;
END_IF;
IF TuningDone THEN
	RETURN;
END_IF

CASE TuningSequence OF
	// Startup - initialize and set to ramp up to setpoint
	E_PIDOptimizationStage.Init: 
		ControlValue := ControlLowVal;
		IF rTrigEnable.Q THEN
			TuFreq(
				IN := FALSE,
				PERIODS := NumCycles,
				RESET := TRUE); 
			b_Min := REAL_MAX ;
			b_Max := REAL_MIN ;
			KP := 0;
			Ki := 0;
			Kd := 0;
			CycleNumber := 0;
			TuningSequence := E_PIDOptimizationStage.RampingUp;
		END_IF;

	// Ramp to setpoint
	E_PIDOptimizationStage.RampingUp:
		ControlValue := ControlHighVal;
		// If we hit the setpoint, transition to ramping down
		IF ProcessValue &gt; ProcessSetpoint THEN
			ControlValue := ControlLowVal;
			CycleNumber := CycleNumber + 1;
			TuningSequence := E_PIDOptimizationStage.RampingDown;
		END_IF;
		
	// Wait for process value to fall below setpoint
	E_PIDOptimizationStage.RampingDown:
		// Once process value falls, either we are done if we hit the cycle count,
		// or we need to start the next cycle.
		IF ProcessValue &lt; ProcessSetpoint THEN
			IF CycleNumber &gt; NumCycles THEN
				TuningSequence := E_PIDOptimizationStage.Done;
			ELSE
				TuningSequence := E_PIDOptimizationStage.RampingUp;
			END_IF;
		END_IF;

END_CASE;


(*Only Start Measuring Min/Max once we've crossed setpoint once this is to make sure we don't take 0 as value*)
IF CycleNumber  &gt; 0  THEN
	b_Min := MIN(b_Min, ProcessValue);
	b_Max := MAX(b_Max, ProcessValue);
	
	
	TuFreq(
		IN := ProcessValue &gt; ProcessSetpoint,
		PERIODS := NumCycles,
		RESET := FALSE); 
	// We don't check the error becuase i'm lazy. In a real system, if the TuFreq goes invalid, it means the data is screwed up and you need to do something.

END_IF
EndTrigger(CLK := TuningSequence = E_PIDOptimizationStage.Done AND TuFreq.OUT &lt;&gt; 0);
IF EndTrigger.Q THEN
    // Calculate amplitude of control variable
    a := ControlHighVal - ControlLowVal;

	// Calculate amplitude of process variable
    b := b_Max - b_Min;

    // Calculate ultimate period and gain
    Ku := (4 * b)/(PI * a);
    Tu := 1 / TuFreq.OUT;

    CASE PIDType OF
    E_PIDOptimizationType.PessenIntegralRule:
        Kp := 0.7 * Ku;
        Ki := (1.75 * Kp) / Tu;
        Kd := 3* Kp * (Tu/20.0);

    E_PIDOptimizationType.SomeOvershoot:
        Kp := Ku /3.0;
        Ki := (2/3.0) * Ku / Tu ;
        Kd := Ku * Tu  / 10.0;

    E_PIDOptimizationType.NoOvershoot:
        Kp := 0.2 * Ku ;
        Ki := 2 * Ku / Tu  / 5.0;
        Kd := 2* Ku * Tu / 3.0;
    END_CASE;
    
    TuningDone := TRUE;
    TuningSequence := E_PIDOptimizationStage.Init;

END_IF;
rTrigEnable(CLK := Enable);
</xhtml>
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            <InterfaceAsPlainText>
              <xhtml xmlns="http://www.w3.org/1999/xhtml">FUNCTION_BLOCK FB_OptimizePID

VAR_INPUT
	// Starts the sequence on the rising edge
	Enable : BOOL; 
	// Set point 
	ProcessSetpoint : REAL; 
	// Process measurement 
	ProcessValue : REAL;
	// Number of automatic adjustment cycles (minimum 2) 
	NumCycles : INT := 2; 
	// Reset
	Reset : BOOL;
	// Low value for the square wave output
	ControlLowVal : REAL;
	// High value for the square wave output
	ControlHighVal: REAL;
	// PID constants to use
	PIDType: E_PIDOptimizationType;
END_VAR
VAR_OUTPUT
	// End sequence
	TuningDone: BOOL;
	// Square wave output for the exitation of the process
	ControlValue: REAL; 
	// Proportional gain
	Kp: REAL;
	// Integral time in S
	Ki: REAL;
	// Derivative time in s
	Kd: REAL;
	// Ultimate Gain 
	Ku: REAL;
	// Ultimate Period
	Tu: REAL;
END_VAR
VAR
	// Enable trigger
	rTrigEnable : R_TRIG;
	// Amplitude of process variable
	b: REAL;
	// Amplitude of control variable
	a: REAL;
    TuFreq: FB_FreqMeasure;      
    b_Min: REAL;
    b_Max: REAL;
	EndTrigger : R_TRIG;    
    TuningSequence: E_PIDOptimizationStage;
    CycleNumber: INT;
END_VAR
VAR CONSTANT
    PI : REAL := REAL#3.14159265358979323846264338327950288;
	REAL_MAX : REAL :=  3.402823E+38;
	REAL_MIN : REAL :=-3.402823E+38;
END_VAR 

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