Download Latest Version StFFT.zip (24.2 kB)
Email in envelope

Get an email when there's a new version of StFFT

Home / StFFT
Name Modified Size InfoDownloads / Week
Parent folder
StFFT.zip 2013-07-31 24.2 kB
0
Symbols.pdf 2013-07-31 19.1 kB
1 1 weekly downloads
StFFT_Omron_FB.cxf 2013-07-31 1.7 kB
1 1 weekly downloads
StFFT.txt 2013-07-31 3.4 kB
0
README.txt 2013-07-31 2.6 kB
0
LICENCE.txt 2013-07-31 7.8 kB
0
Totals: 6 Items   58.9 kB 2 
StFFT - Fast fourier transform on Structured text
------------------------------------------------------------------------------

StFFT is FFT implementation on PLC environment
written with IEC-61131-3 Structured text programming language.
StFFT uses iteration (loops) contrary to more commong recursion,
because PLCs don't support recursion in Function block calls.
For the same reason dependencies have been kept minimum,
only sine and cosine functions are required from the PLC.


FILES
------------------------------------------------------------------------------
README.txt - This file
LICENCE.txt - LGPL licence file
StFFT.txt - Program code for StFFT
Symbols.pdf - Omron PLC style symbol table
StFFT_Omron_FB - Complete function block for Omron PLCs


INSTALLING on Omron PLC
------------------------------------------------------------------------------
Complete function block is provided for Omron PLCs. To use the function block,
open your project, left-click on 'Function Blocks' on project tree and select
'Insert Function Block' -> 'From File...'


INSTALLING on other PLCs
------------------------------------------------------------------------------
1. Create new function block
2. Define symbols (variable) defined in Symbols.pdf
3. Copy-Paste program code from StFFT.txt to your ST editor
4. Anything else your PLC environment might need...


USAGE
------------------------------------------------------------------------------
To use your freshly installed function block in structured text program, just
call the function block like this
StFFT( L, x_real, x_imaginary )
where L is length of data vectors, x_real is array (pointer) containing real
components of data, x_imagianry is array (pointer) containing imaginary
components of data. StFFT transforms original data arrays to frequncy domain
without returning anything!

You can also use StFFT to compute inverse FFT, since inverse FFT (IFFT) is
IFFT = 1/L*StFFT( L, x_real, -x_imaginary ),
so to get back to time domain:
1. Multiply imaginary data with -1 (complex conjugate)
2. Call StFFT for complex conjugate
3. Divide all elements by data length (L)


LICENCE
------------------------------------------------------------------------------
StFFT is licenced under LGPLv3 and Commercial licence
for commrecial licencing contact tamitech@tamitech.fi
Copyright:
Tamitech Automation Oy - 2013
tamitech@tamitech.fi


AUTHOR
------------------------------------------------------------------------------
Jaakko Pasanen
jaakko.pasanen@tamitech.fi, jaakko.o.pasanen@gmail.com
Source: README.txt, updated 2013-07-31