LabVIEW: missing block diagram

Question

I have a two broken VIs with front panels that open fine, but I can't edit or run them, or open theis block diagrams.

One of these was made as a replacement for the first when it started to have this problem. I need to at least find out how to avoid this problem in future, so I don't lose work on bigger VIs.

I'm not sure if it makes any difference, but I very recently upgraded to LabVIEW 2013.

Thank you in advance.

This is the error I get when I try to run them:

" VI has a bad connection to or cannot find a subVI or external routine.

This VI has a bad connection to or cannot find a subVI or external routine but it has no block diagram to show or fix the error. You must find or correct the subVI or external routine. Check for more information in the Explain dialog box in Get Info. "

Before reverting to a previous version (using dropbox) I got a different error with one of them:

" LabVIEW: Generic error.

An error occurred loading VI 'sweep harmonics first test.vi', LabVIEW load error code 6: Could not load the block diagram. "

Answer 1

One situation how this happened.

Sometime LabVIEW crashes, and it restart. After restart, LabVIEW will ask you to recover the autosaved code.

I personally always discard those autosaved code. If you do choose to recover autosaved code, there is a chance the recovered code is corrupted. Once you save corrupted code to disk, you are probably going to lose the ability to open/save the block diagram ever again.

Having a version control system is usually a way to avoid minimize the damage when LabVIEW crashes. At worst, you loose maybe an hour worth of work.

Answer 2

If you can't open Block Diagram of your VI, first check the suggestion by @Rodrigo - it is most likely just a "compiled" VI, which has Block Diagram removed.

If you think there is Block Diagram inside and it is just corruped - you may contact NI support. And if you want to look deeper by yourself, extract the VI to XML using pyLabview, and look into the XML - there you can modify every single part of the VI. For example, you may start removing parts until it starts working.

I wouldn't go into manual VI editing unless you have at least a dozen of affected files though. For a single file, it will be faster to re-create it in LabVIEW instead of trying to understand the internals. If many files are affected - may be worth finding the issue in one, as other files probably have the same glitch, so you can make a script which extracts, modifies and re-creates VIs automatically.