Labview 8.0 Crashes on Read Waveform from File

[jasonhill]

Has anyone had problems getting the Read Waveform from File.vi to work in Labview 8.0?  It worked fine in Labview 7.1, but now it crashes to the desktop. 

I cannot get it to work with my test data and I cannot get it to work with an array of sinewaves I rigged up to test with.  I can get it to work ONCE if I only look at the first file in the record and only then if I (a) do not display it on a waveformgraph, and (b) only run it once.  If I run it again, the Labview crashes.

The crash gives me a memory dump and offers to send it off to microsoft, not terribly useful for a BSME like myself that just wants the damned thing to work.

I am running LabVIEW 8.0 on a fully updated Windows XP machine.

[jasonhill]

After a bit of noodling with Read Waveform from File.vi, I have discovered that NI worked over Read WDT Array Dlog File+.vi presumably to bring it into compliance with the new datalog format.  They replaced the trusty Read File.vi with a hodge-podge of Set Datalog Position.vi, Read Datalog.vi, and Get Datalog Position.vi

My system crashes on the Get Datalog Position.vi and since it is one of the "atom" functions, I cannot pull it apart any further to see why it is misbehaving.  I think I shall punt and call the NI wizards.

[jasonhill]

Its a bug.  But not where I had thought it was.  Read WDT Array Dlog File+.vi is working as expected.  Unfortunately, it is trying to read a datalog that has been explicitly prevented from reading.  If the waveform is sufficiently large (an mine definitely are), LabVEIW will crash before it can express an error message.

The good news is there is a work around. 
1. Open the Read Waveform from File.vi
2. Open the Open Create Replace WDT Array Dlog File.vi
3. There are a whole bunch of nested case structures. Look at the very outermost False and the larger of the next level in False.  There should be a note "Try to open the file." in the upper left corner of the structure.
4.  There is a Deny Access.vi with a conversion dot just below the note.  It looks a little like a Do Not Enter sign.
5.  The primitives are all stacked on top of eachother making wire manipulation difficult, so stretch it out a bit.
6.  Delete the Deny Access.vi. For reasons I do not understand, it is not allowing read access even when explictly told to allow read access.  It is a bug.  It has been reported.  I do not know its current status.
7. Plug the "refnum" from the Open/Create/Replace Datalog into the case structure terminal.
8. Plug the "error out" into the Unbundle.
9. Clean up the wires, delete the stray [1] constant, and save as Open Create Replalce WDT Array Dlog File Workaround.vi (or whatever suits your fancy).

Removing the Deny Access.vi does violate NI's policy of preserving the data at all costs.  While I cannot see any way for the data to get accidentally overwritten, there is nothing expressly preventing it from being overwritten.  Personally, I am willing to run the tiny risk that my data will be damaged in exchange for being able to actually read it.

The workaround works.  I am sticking this in here to help anyone having similar problems.

[becktho]

Hi Jason

You can't imagine how this thread helped me.

I discovered the problem when trying to read waveform files saved under LV7.0. When I tried to open a file saved under LV8.0, I had no problem (ok that's more than logical). When opening the LV7.0 file, LV asked me to convert the file. When I clicked yes, LV crashed.

So I implemented your workaround and voilà - it works.

Thanks a lot man...

Thomas

[jasonhill]

Glad I could help

[JLS]

Hello all,

Just wanted to chime in that this is a known issue and is being addressed.  Although I can't be more specific, this should be fixed in a future version of LabVIEW.

Best Regards,

JLS

[THailey3]

This was reported to R&D (# 3UD97S00) and was fixed in LabVIEW 8.0.1. Here is a link to the LabVIEW 8.0.1 maintenance release and here is a link to the current evaluation software download for LabVIEW.

Thanks!