Reconstruct cluster from TDMS

[nickb34]

I've been able to successfully save my array of cluster data to a TDMS file using the following block diagram:

I've been trying to reconstruct my data using the following block diagram:

When the program gets to the nested FOR loop, it never enters. I placed a probe on the data going into that loop and there is certainly a large array going into it. Does anybody have any ideas for me? Furthermore, should I try a different method to save and restore data? (It seems like TDMS isn't very friendly unless you give it waveform data)

Thanks for any help!

[0utlaw · Accepted solution]

Hi Nick,

The number of iterations in the for loop is determined by the smallest array- in this case I would hazard a guess that your cluster definition array (DataArrays.PeakDataArray) is empty- the auto-index input is going to see zero elements and skip the loop.

You'll want to index that array one loop out to provide the cluster definition.

*edit*: By "one loop out", I mean you'll need to use an index array function, preferably outside the outer for loop- you don't want to auto-index just to get the cluster definition.

Regards,

[nickb34]

Tom,

You sir are correct... I had done that previously for breaking out the waveform signals, but missed it on this one.

To my other question, is there a better method for saving and restoring clustered data?

[0utlaw]

Hi Nick,

Datalog files might be what you're looking for.  They are extremely convenient when storing small-to-moderate amounts of cluster data, but there are a few caveats:

1) You're essentially creating a custom binary file type that is only interpretable using your definition cluster and the datalog functions - this means data export to other environments/programs will be difficult and probably have to go through a datalog interpreter and you'll need that cluster definition to unpack the data.  This makes most datalog solutions application-specific (It's hard to re-use the code elsewhere).

2) The file size is currently capped at 2 GB

3) See (1).  You can't open a datalog in Excel.

There are a few decent examples of the functions being used, such as this one:

Example: Super Heroes vs Super Villains (an intro to Datalog Files)

https://forums.ni.com/t5/Example-Code/Super-Heroes-vs-Super-Villains-an-intro-to-Datalog-Files-Using...

XML is another good (and more portable) option, but will probably require more time up front to get going.

I've seen a few different cluster pack/unpack tools around, one called "Read Anything" is included in the free MGI library and saves cluster data in config (text) files.

Regards,

[Yamaeda]

Modify the inner loop, let it build an array and place the build array outside and afterwards and add the two arrays together.

/Y