FB_PMA_Spectrum_Quantiles_1Ph
The function block FB_PMA_Spectrum_Quantiles_1Ph calculates the magnitude spectra of the current and voltage values like the function block FB_PMA_Spectrum_1Ph. In addition, p-quantiles of the spectrum distribution can be calculated. The quantiles and their number can be configured individually.
The input buffer is provided via the function block FB_PMA_Source_1Ph. The size of the input buffer is half the window length.
By way of example, possible FFT and window lengths are shown in the following table:
FFT length | Window length | Buffer length | |
|---|---|---|---|
512 | 29 | 400 | 200 |
1024 | 210 | 800 | 400 |
2048 | 211 | 1600 | 800 |
4096 | 212 | 3200 | 1600 |
8192 | 213 | 6400 | 3200 |
16384 | 214 | 12800 | 6400 |
Memory properties
The function block takes into account all input values since the instantiation. If the Reset method has been called since the start, all input values since its last call will be taken into account.
Syntax
Definition:
FUNCTION BLOCK FB_PMA_Spectrum_Quantiles_1Ph
VAR_INPUT
nOwnID : UDINT;
tTransferTimeout : LTIME := LTIME#500US;
stInitPars : ST_PMA_Spectrum_Quantiles_InitPars;
END_VAR
VAR_OUTPUT
bError : BOOL;
ipResultMessage : I_TcMessage;
bNewResult : BOOL;
nCntResults : ULINT;
END_VAR
Inputs
The input parameters of this function block represent initialization parameters and have to be assigned during the declaration of the function block instance (alternatively: Init method). They may only be assigned once. A change at runtime is not possible.
Name | Type | Description |
|---|---|---|
nOwnID | UDINT | Identifies the function block instance with a unique ID. This must always be greater than zero. A proven approach is to define an enumeration for this purpose. |
tTransferTimeout | LTIME | Setting of the synchronous timeout for internal multi-array forwardings. See Parallel Processing in Transfer Tray. |
stInitPars | Function block-specific structure with initialization parameters. The parameters must match the definition of the input and output buffers. |
Outputs
Name | Type | Description |
|---|---|---|
bError | BOOL | TRUE if an error occurs. |
ipResultMessage | I_TcMessage | The interface offers detailed information about the return value. |
bNewResult | BOOL | TRUE once new results have been calculated. |
nCntResults | ULINT | Count value is incremented with new output data. |
Methods
Name | Description |
|---|---|
The method is called in each cycle to execute the calculations from the input buffer when new data is present. | |
To minimize CPU usage, it may be necessary to use the CallEx method. In contrast to the Call method, the quantiles are not calculated after each spectrum calculation, but only after a configurable number of calculations. | |
Alternative to the function block initialization | |
As an alternative to the Call method, the method can be called in each cycle if no calculation is to take place. The incoming input buffer is then forwarded accordingly. | |
The method is called in order to reconfigure the function block during the runtime. | |
This method deletes all the data sets already added. Alternatively, automatic resetting can be used on the CallEx method. |
Sample
VAR CONSTANT
cOversamples : UDINT := 10;
cFFT_Length : UDINT := 4096;
cWindowLength : UDINT := 3200;
cSourceInitPars: ST_PMA_Source_InitPars := (
nBufferLength := cWindowLength/2);
cSpectrumQuantilesInitPars : ST_PMA_Spectrum_Quantiles_InitPars := (
nFFT_Length := cFFT_Length,
nWindowLength := cWindowLength,
fSampleRate := cOversamples * 1000,
eScalingType := E_PMA_ScalingType.PeakAmplitude,
eWindowType := E_PMA_WindowType.HannWindow,
bTransformToDecibel := FALSE,
fDecibelThreshold := GVL_PMA.cMinArgLog10,
fMinBinnedVoltage := 0.0,
fMaxBinnedVoltage := 300,
fMinBinnedCurrent := 0.0,
fMaxBinnedCurrent := 2,
nBins := 10,
nNumQuantiles := 2,
aQuantiles := [0.5, 0.9]);
END_VAR
VAR
aVoltage AT%I* : ARRAY[1..cOversamples] OF LREAL;
aCurrent AT%I* : ARRAY[1..cOversamples] OF LREAL;
fbSource : FB_PMA_Source_1Ph := (nOwnID := 1, aDestIDs := [2], stInitPars := cSourceInitPars);
fbSpectrumQuantiles : FB_PMA_Spectrum_Quantiles_1Ph := (nOwnID := 2, stInitPars := cSpectrumQuantilesInitPars);
aSpectrumVoltage : ARRAY[1..cFFT_Length/2 + 1] OF LREAL;
aSpectrumCurrent : ARRAY[1..cFFT_Length/2 + 1] OF LREAL;
aSpectrumQuantilesVoltage : ARRAY[1..cFFT_Length/2 + 1, 1..2] OF LREAL;
aSpectrumQuantilesCurrent : ARRAY[1..cFFT_Length/2 + 1, 1..2] OF LREAL;
bNewResult_Spectrum : BOOL;
bNewResult_Quantiles : BOOL;
END_VAR
// Call source
fbSource.Call(ADR(aVoltage), ADR(aCurrent), SIZEOF(aVoltage), 0);
// Call algorithm
fbSpectrumQuantiles.CallEx(
5,
FALSE,
ADR(aSpectrumVoltage),
ADR(aSpectrumCurrent),
SIZEOF(aSpectrumVoltage),
ADR(aSpectrumQuantilesVoltage),
ADR(aSpectrumQuantilesCurrent),
SIZEOF(aSpectrumQuantilesVoltage),
ADR(bNewResult_Spectrum),
ADR(bNewResult_Quantiles));
Requirements
Development environment | Target platform | PLC libraries to include |
|---|---|---|
TwinCAT v3.1.4024.0 | PC or CX (x86, x64) | Tc3_PowerMonitoring |