error 20315; "The waveform dt parameter is <= 0".

[sean m]

Hi All,

I'm running a Labview application, and upon starting it gives the above error.  If I stop the program at that error it takes me to the block diagram

shown in the attached screenshot.  Any ideas as to how to fix this?  I can't see the dt signal at the top level.

Thanks,

Sean

[Wayne.C]

Attachment?

[sean m]

Sorry, attachment is here.

[Wayne.C]

Sean,

Suggest you hook up the error cluster and run in Highlight Execution mode to determine exactly where the error is being generated..

[Coq_Rouge]

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sean m wrote:

Hi All,

I'm running a Labview application, and upon starting it gives the above error.  If I stop the program at that error it takes me to the block diagram

shown in the attached screenshot.  Any ideas as to how to fix this?  I can't see the dt signal at the top level.

Thanks,

Sean

---

Waveform Data Type
The waveform data type carries the data, start time, and delta t of a waveform. You can create a waveform using the Build Waveform function. or "unbundle" it with the Get Waveform Components function 

[Dennis_Knutson]

Since the front panel control is a waveform array, you just have to look at what the dt is. A simple breakpoint will suffice.

Since you are apparentlly creating the waveform array in the top level, using probes will let you see the actual data and where the problem is being created.

[sean m]

The program is quite complicated so there are many steps that would have to execute in highlight execution mode before I can see what's executing in this vi.

I also tried adding the error cluster, the only extra info I got was that the error seems to come from ma_CheckWaveformTiming.vi.

I can't see the dt variable that the original error is about.

[Dennis_Knutson]

Seeing the dt value is an extremely simple task. If you don't feel like setting a breakpoint for some reason, just place a probe on the waveform array input to the subVI. This is done in the main and is one the basic debugging skills you need to acquire (as is breakpoints). You have not posted the main so all we can do is tell you how to find the source of the problem.

[sean m]

Looks like a few others replied while I was writing my previous reply.  I set a breakpoint on the waveform wire (see screenshot) and when the error occured the waveform seemed to be empty, i.e. did not contain a dt value.  Could this be causing the error?

[Dennis_Knutson]

Of course it is the cause of the error. You need to track down where in the main VI you are creating the waveform array and why at least one element is empty. Did you try to look at the array itself to see if all elements are empty? In the main, put a probe on the input to the subVI!

If the number of waveforms in the array is variable, you should be doing the analysis inside a for loop instead of using a fixed Index Array function.

Message Edited by Dennis Knutson on 05-13-2009 01:26 PM