49 lines
1.2 KiB
Plaintext
49 lines
1.2 KiB
Plaintext
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#More recent samples have higher weight. Better step response than SMA.
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FUNCTION_BLOCK FB_WMA
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VAR_INPUT
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xEnable : BOOL;
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rInput : REAL;
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iWindowSize : INT := 8; // Max 16
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END_VAR
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VAR_OUTPUT
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rOutput : REAL;
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END_VAR
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VAR
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arBuffer : ARRAY[0..15] OF REAL;
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iIndex : INT := 0;
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iCount : INT := 0;
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iWin : INT;
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rWeightSum : REAL;
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rValSum : REAL;
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i : INT;
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iPos : INT;
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rWeight : REAL;
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END_VAR
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IF NOT xEnable THEN
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iIndex := 0; iCount := 0; rOutput := rInput;
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RETURN;
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END_IF;
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iWin := MIN(MAX(iWindowSize, 1), 16);
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// Store newest sample
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arBuffer[iIndex] := rInput;
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iIndex := (iIndex + 1) MOD iWin;
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IF iCount < iWin THEN iCount := iCount + 1; END_IF;
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// Calculate weighted sum (weight = position, newest = highest)
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rWeightSum := 0.0;
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rValSum := 0.0;
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FOR i := 0 TO iCount - 1 DO
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// Most recent sample is at (iIndex - 1), going back
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iPos := (iIndex - 1 - i + iWin * 2) MOD iWin;
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rWeight := INT_TO_REAL(iCount - i); // Newest gets weight=iCount, oldest=1
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rValSum := rValSum + arBuffer[iPos] * rWeight;
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rWeightSum := rWeightSum + rWeight;
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END_FOR;
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IF rWeightSum > 0.0 THEN
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rOutput := rValSum / rWeightSum;
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END_IF;
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