Data clipping when using SGL file write

[oxygen28]

Hi all,

I am using buffered data acquisition with Binary save. I have done buffered data acqusition but when i try to record data in Binary format and view it later with my software axoscope or clampex. The data is clipped. I use the vi write to SGL file. I have also attached my VI. Please look at it and tell me if i have to make any changes.

Thanks,
Srikanth

[altenbach]

It is not clear to me why you multiply your data by 2^32 before saving! SGL has only about 6 decimal digits of resolution so your data is probably truncated.

Just remove the multiplication by 2^32 and you will save exactly the same data as you see on your indicators. 🙂

(It is also possible that your data looks "distorted" because your other software packages expects the binary data to be in little-endian format. Remember, LabVIEW is big endian on all platforms. There are many simple solutions to this issue, but let's first see if this is even the problem. What OS are you using?).

Message Edited by altenbach on 02-26-2005 02:29 PM

[oxygen28]

Hi altenbach,
Thanks for helping me out. I tried removing the factor of 2^32 but it is not working. The software which i use is freely available for download "Axoscope" or "Clampex" Both these softwares have an option to check whether the data is in Litten Endian or Big endian format. I tried changing the way the software reads ie., bigendian to little endian and so on. But it does not work still. Is theere an alternative which u could propse as I am trying on this for the last 2 months. I use WINDOWS XP as my OS.

Thanks,
Srikanth

[Johnner]

Srikanth,

Why not just use "Write to Spreadsheet File" instead of going with the binary format? That's often the most foolproof way to transfer datasets between applications.

I actually played around with AxoScope a little bit and found that I could read in integer binary datasets, but not floating-point datasets, from LabVIEW. Maybe that's why you were scaling the data before saving it? I found that I could scale SGL data by a factor of (2^15/max value), convert to I16, save to binary file, and then successfully read it into AxoScope, though it seemed irritating that AxoScope didn't provide for arbitrary range conversion and forced me to choose between +-10V, +-5V, etc.

It wasn't clear why the program wouldn't read in SGL datasets. Perhaps the datatype somehow differs from LabVIEW's SGL? But go with the Spreadsheet File method and you don't have to worry about this problem.

One additional question is: why are you analyzing your data in AxoScope if you have LabVIEW at your disposal? LabVIEW seems more flexible from an analysis and presentation perspective, so why not just do any data manipulation and display there?

Hope it helps,
John

[oxygen28]

Hi Johnner,

Thanks for helping me out. It worked I had to convert it to SGL before i write it to a file. The reason i dont want to write it to excel sheet is because i have other software that work on this binary data. Thanks for your help!!!!

Srikanth