Constant Wired to Case structure Causes Crash

[Louis Manfredi]

Hi Folks:

I seem to remember reading something about this somewhere before, but I can't find the reference, so I'll open it as a new topic...

I have an old vi from LV 8.2 which had a case structure with a constant wired to it to comment out a section of code. With the beginning of a new project, I transitioned to LV 8.5. When I go to load the vi, I get the warning message:

fair enough, but LabVIEW crashes as it posts this message "(not responding)" in window title...

NI suggested that I open the vi in LV 7.1, remove the case structure there, and reload, which would have worked, if as I originally thought, the vi was a 7.1 vi. Unfortunately, I had saved it as and 8.2 -- too new for my copy of 7.1, won't open on 8.5, and I let 8.2 go away in the process of upgrading to 8.5.

A known issue, I asked support for the CAR, but there isn't one, since this is a feature, not a bug.

Waiting for a work-around from NI support, and worst case, fortunately the vi is pretty small and won't be too hard to rewrite from scratch, but heads up if you've got lots of stuff using the old style constant-and-case-structure conditionals and you are about to upgrade.

Best Regards, Louis

[Mark Balla]

QUOTE(Louis Manfredi @ Jan 16 2008, 03:32 PM)

Hi Folks:

I seem to remember reading something about this somewhere before, but I can't find the reference, so I'll open it as a new topic...

I have an old vi from LV 8.2 which had a case structure with a constant wired to it to comment out a section of code. With the beginning of a new project, I transitioned to LV 8.5. When I go to load the vi, I get the warning message:

http://lavag.org/old_files/monthly_01_2008/post-1144-1200518433.png' target="_blank">

fair enough, but LabVIEW crashes as it posts this message "(not responding)" in window title...

NI suggested that I open the vi in LV 7.1, remove the case structure there, and reload, which would have worked, if as I originally thought, the vi was a 7.1 vi. Unfortunately, I had saved it as and 8.2 -- too new for my copy of 7.1, won't open on 8.5, and I let 8.2 go away in the process of upgrading to 8.5.

A known issue, I asked support for the CAR, but there isn't one, since this is a feature, not a bug.

Waiting for a work-around from NI support, and worst case, fortunately the vi is pretty small and won't be too hard to rewrite from scratch, but heads up if you've got lots of stuff using the old style constant-and-case-structure conditionals and you are about to upgrade.

Best Regards, Louis

If you post it I will try and open it in 8.2 and convert it to 8.5

[Ton Plomp]

QUOTE(Louis Manfredi @ Jan 16 2008, 10:32 PM)

A known issue, I asked support for the CAR, but there isn't one, since this is a feature, not a bug.

A feature?

Are you sure about that, there's a feature that allows LabVIEW to crash on a 8.2 VI?

What's special about that VI?

And the change from constant to hidden control should have happened in 8.2, if it happened in 8.5 the VI would have been prior to 8.0, I don't think the 'constant case' check is applied on a 8.x VI.

Could you read the VI version (with the http://zone.ni.com/reference/en-XX/help/371361B-01/lvprop/app_get_vi_version/' target="_blank">app.Get VI Version method)?

If you get the message on an 8.2 VI something strange is going on (IMHO).

Ton

[crelf]

QUOTE(tcplomp @ Jan 17 2008, 12:19 AM)

I don't think the 'constant case' check is applied on a 8.x VI.

I can't say for sure, but maybe the check is applied to any version below the current one (?) So you should be able to create a new VI in 8.2 with a constant feeding a case structure, then open it in 8.5 and have it convert - but why? If you've got a constant feeding a case structure in 8.2 then it's going to act the same way as in 8.5. Intriguing - is anyone with 8.5 able to try it? I've attached an 8.2 example VI.

[Aitor Solar]

QUOTE(crelf @ Jan 17 2008, 02:36 PM)

Intriguing - is anyone with 8.5 able to try it? I've attached an 8.2 example VI.

It doesn't change to a control (and that's the correct behavior, IMHO).

Saludos

Aitor

[Ton Plomp]

QUOTE(Aitor Solar @ Jan 17 2008, 02:55 PM)

It doesn't change to a control (and that's the correct behavior, IMHO).

Saludos

Aitor

Ditto

[crelf]

QUOTE(Aitor Solar @ Jan 17 2008, 08:55 AM)

It doesn't change to a control (and that's the correct behavior, IMHO).

Great - and yes, I agree: the only time it should change is when upgrading a VI from <8.0 to >=8.0.

[Rolf Kalbermatter]

QUOTE(crelf @ Jan 17 2008, 08:36 AM)

I can't say for sure, but maybe the check is applied to any version below the current one (?) So you should be able to create a new VI in 8.2 with a constant feeding a case structure, then open it in 8.5 and have it convert - but why? If you've got a constant feeding a case structure in 8.2 then it's going to act the same way as in 8.5. Intriguing - is anyone with 8.5 able to try it? I've attached an 8.2 example VI.

This dialog should only be triggered when upgrading a pre 8.0 VI. So I'm afraid it is probably more a question of a corrupted VI somehow. For some reasons LabVIEW 8.5 does believe it is a pre 8.0 VI and applies that check but then stumbles over something else that is inconsistent in respect to this assumption.

A bug? Well strictly speaking the bug happened either when saving that VI in 8.2 or the VI was corrupted somehow in such a way that 8.2 did not have trouble to read it but 8.5 has. It would be of course fine if LabVIEW 8.5 would just inform you of the inconsistency and continue instead of hanging, but there are miriads of things that can be inconsistent and anticipating them all is not very easy and checking them all is even less practical.

I do think that technical support would be interested in this VI to be attached to the CAR so that LabVIEW development may look into the kind of corruption and maybe apply an extra check in the VI loader.

Rolf Kalbermatter