[SciPy-User] dtype of LabView binary files

Christoph Gohlke cgohlke@uci....
Tue Nov 9 22:08:55 CST 2010



On 11/9/2010 2:34 PM, Xunchen Liu wrote:
>
> Hello,
>
> It seems there is only one web page here talking about the dtype of the
> binary file saved from Labview:
>
> http://www.shocksolution.com/2008/06/25/reading-labview-binary-files-with-python/
>
> I followed Travis' suggestion on that page to convert one of my Labview
> binary file using
>
> data=numpy.fromfile('name',dtype='>d')
>
> but this gives a array doubled the shape of my recorded data and also
> the value of the data are not right.
>
> For example, the attached is the text file and binary file saved by Labview.
>
> the text file reads:
>
> array([-2332., -2420., -2460., ...,  1660.,  1788.,  1804.])
>
> while the binary file reads (with dtype='>d')
>
> array([-3.30078125,  0.        , -3.30297852, ...,  0. ,
> -2.6953125 ,  0.        ])
>
> Anyone knows what dtype I should use, or how should I build the correct
> dtype for it?
>
> Thanks a lot!
>
> Xunchen Liu
>

Those data are big Endian, 80-bit IEEE extended-precision numbers, 
flattened to 128-bit extended-precision in the binary file. Not sure 
if/how such data can be read into numpy without bit manipulations.

<http://zone.ni.com/reference/en-XX/help/371361B-01/lvconcepts/how_labview_stores_data_in_memory/>
<http://zone.ni.com/reference/en-XX/help/371361E-01/lvconcepts/flattened_data/>

Christoph


More information about the SciPy-User mailing list