Retrieving datalog files

[greg@sontek]

I have a log file created with an old version of a VI. I do not have a backup of the VI before the front panel was modified, so I cannot access the log file. There are a lot of fields on the front panel, so it is not something that can easily be re-created (I don't even know exactly which ones were on this version). Is there any way to easily retrieve this old data?

[SVences]

Hello �

From the problem description you provided, I understand that you have a LabVIEW datalog file that was created with a VI that you don�t have any more. You want to access the datalog file but you don�t know how the data was written to it (you don�t know the datalog type).

If this is correct, then I will have to say that unfortunately in this case there is no way of accessing the datalog file. To read the record of information from the datalog file, you must wire an input to the datalog type of the Open File function that exactly matches the data type of the records stored in the file, including numeric data types and cluster order. So, if you don�t know the way the information was saved, you won�t be able to read it.

If I misunderstood y
our question, please let me know.

S Vences
Applications Engineer
National Instruments

[greg@sontek]

This sounds like exactly my problem. Is there any way that I can submit this as a feature request? This does not seem like an unreasonable/uncommon thing to have happen and basically makes a lot of data trash. It seems to me that there should be some way to easily exactly front panel information from the file. Is there a format definition of the datalog file published anywhere, or is this held internally at NI?

Thanks,
Greg

[rolfk]

greg@sontek wrote:

> This sounds like exactly my problem. Is there any way that I can
> submit this as a feature request? This does not seem like an
> unreasonable/uncommon thing to have happen and basically makes a lot
> of data trash. It seems to me that there should be some way to easily
> exactly front panel information from the file. Is there a format
> definition of the datalog file published anywhere, or is this held
> internally at NI?

I don't think it was ever published and there are modifications to the
format with most major LabVIEW versions. However I'm pretty sure that
part of the header in a datalog file corresponds with the "type string"
returned from the "Flatten to String" function from a cluster with the
same control typ
es and their order as the controls on the front panel.

The contents of this "type string" is documented in an Application Note
on the NI site so it shouldn't be to difficult to get the original
format back with the help of a Hex Editor.

Rolf Kalbermatter

[SVences]

Hello �

The idea of needing to know the exact data type of the records stored in the datalog file is to be able to create �confidential files�.

For example, say that you own a company dedicated to teaching classes. The instructors travel all over the country to teach. And you need a way of evaluating the class and the instructor.
Having the students fill out a paper survey and give it to the instructor might not be very reliable, because the students know that the instructor would be seeing the information and they might not express their opinions freely.
Same thing would happen if you had an electronic survey saved in a file that can be accessed by the instructor.
With datalog files, the instructor doesn�t know what the datalog type
of the record is and cannot read the file. In this case the surveys are truly confidential and the only person who can access the information is you, back in corporate, because you know what the datalog type is.

Having a way of knowing what the datalog type is directly from the file would defeat the purpose.

Anyway, to address your question, you can submit this or any other suggestions in the Product Suggestion Center.

Hope this helps!

S Vences
Applications Engineer
National Instruments