topic Re: Frozen screen during execution in LabVIEW

Frozen screen during execution

ebragafreitas — Tue, 12 Jun 2007 18:12:52 GMT

Hi there,

I developed a VI to acquire pressure data from 48 sensors. During execution, the front panel freezes and the acquisition just stops. No error message appears and i just can interact with other objects, like graphs and buttons. Remember that the VI keep running, but the acqusition stucks. I'm using LabView 6.1. I'd apreciate if you could help me.

Thanks,

Re: Frozen screen during execution

altenbach — Tue, 12 Jun 2007 18:58:34 GMT

We need to see the code!

Some things to look out for:

An event structure that locks the front panel (the default!), but never completes.
Don't set the VI priority to e.g. timecritical, or user interactions are postponed.
how is error handling?
How does it communicate with the sensors?
Are there any third party dll calls?
...

Re: Frozen screen during execution

ebragafreitas — Tue, 12 Jun 2007 20:39:34 GMT

Here are the codes, take a look at them, please.

The labels are in portuguese, but it´s easy to understand cause the words are similar to the english ones.

The error handling shows only some warnings, like ''..vi recomended input is unwired". These warnings don´t affect the execution.

The sensors comunicate with the soft through 2 boards ni daq PCI E-6031 and PC1 E-6024, respectively.

What do you mean about third party dll calls?

Re: Frozen screen during execution

RavensFan — Wed, 13 Jun 2007 03:32:46 GMT

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Re: Frozen screen during execution

ebragafreitas — Wed, 13 Jun 2007 14:14:48 GMT

The codes.

Re: Frozen screen during execution

altenbach — Wed, 13 Jun 2007 15:10:09 GMT

Sorry, troubleshooting from pictures is probably not possible in this case. Can you attach a real VI instead?

The code itself is much more complicated than needed, because there is a lot of repetitive code. Still, it would not explain a lockup.

Re: Frozen screen during execution

ebragafreitas — Thu, 14 Jun 2007 17:45:12 GMT

Re: Frozen screen during execution

Ben — Thu, 14 Jun 2007 18:03:50 GMT

Now that we have seen the code, two questions.

1) DId this application ever run correctly?

2) Have you tested your hardware using MAX?

Ben

Re: Frozen screen during execution

ebragafreitas — Thu, 14 Jun 2007 18:10:04 GMT

Yes, how i said, the program runs correctly, but the acquisition stop some times (screen gets freeze).

And i've already tested the boards using measurement and automation explorer. They're OK.

Re: Frozen screen during execution

Ben — Thu, 14 Jun 2007 18:13:58 GMT

Then use the Task Manager to see if another task is getting in the way of your application.

It would also be helpful if you put indicators on the outputs of all of your "AI" to see if an erro is returned.

Ben

Re: Frozen screen during execution

altenbach — Thu, 14 Jun 2007 18:20:13 GMT

I agree with Ben.

This code is a nightmare!

Duplicate code everywhere in deep stacks of stacked sequences, overlapping tunnels and wires.

Then you are building infinite arrays via local variables without ever resetting them. Every time you run the VI in the same session, your arrays will start at the size from the last run.

Use arrays instead of discrete code paths, replace the stacked sequences with autoindexing FOR loops containing exactly one instance of the code, and things will become more manageable.

Also, your "Prompt.vi" needs a small delay inside the loop. It does not need to spin millions of times/second. How fast can you possibly enter the texts? Give it 100ms!

Maybe once the code is cleaned up, debugging will be possible. 🙂

Re: Frozen screen during execution

ebragafreitas — Thu, 14 Jun 2007 19:10:17 GMT

Ok, i'll try to do it. Ben, what's Task Manager?

Thanks

Re: Frozen screen during execution

Ben — Thu, 14 Jun 2007 19:34:05 GMT

right click on your task bar (bottom of the screen) and cleck "Task Manager".

It is a utility that ships with Windows XP and allows you to monitor how much CPU is used memory etc.

It also (on another tab) lists all of your process and the amount of CPU being used by each task.

Ben

Re: Frozen screen during execution

ebragafreitas — Fri, 15 Jun 2007 22:11:36 GMT

Ben, i´ve cheked the task manager and I´ve noticed that about 70% percent of CPU was being used during execution and when i was handling graph palette features, like zoom, this rate turned to 100%! At this point, usually, the aquisiton stops.

Re: Frozen screen during execution

altenbach — Fri, 15 Jun 2007 22:31:50 GMT

More important would be to monitor memory.

As I said above, you are growing infinite arrays in shift registers, so the code constantly need to perform expensive memory allocations. Are you sure you're not runing out of memory?

Re: Frozen screen during execution

RavensFan — Sat, 16 Jun 2007 00:54:42 GMT

@altenbach wrote:

I agree with Ben.

This code is a nightmare!

Duplicate code everywhere in deep stacks of stacked sequences, overlapping tunnels and wires.

Maybe once the code is cleaned up, debugging will be possible. 🙂

This code is a structural nightmare, but it is almost pretty in how all the duplication is organized. It must have taken a huge amount of work to organize all those wires so they overlap. And tunnels on top of tunnels. The author must have carpal tunnel syndrome from all that mouse clicking and wire moving! And to duplicate a case structure 48 times and make minimal changes to each case? It is a rather neat job of programming considering it must have been at least 20 times the work as if the loops were organized properly.

Re: Frozen screen during execution

ebragafreitas — Fri, 22 Jun 2007 19:54:31 GMT

The task manager shows that the memory alocation is increasing reasonably fast. What should I do? I need to store all this data in so many arrays cause they're been plotted on a XY graph.