Error -20315 appear on the data saved in lvm files.

[Kiwi331]

Dear all,

I use NI9205 as data acquisition board and DAQ assist in LabVIEW to get the signals. Sampling frequency was set to 250Hz, which means the dt should be equal to 0.004. The data were saved using Write to files as lvm files. When I read the data, the error 20315 shows up.  I found that in the saved file, dt all equal to 0. Open a small lvm file by notepad, I see the delta_x 0.000000. The files of data I have already acquired are huge, which means I cannot change Delta_x manually. Do you have any good ideas of how do I handle these files in Labview regarding the signal processing? So far I can not use almost anything because of the error.

Thank you very much in advance.

Kiwi

[Morini]

Hi Kiwi,

What is the Number of Samples in the DAQAssistant? Can you please post the VI or just a screendump of the DAQassistant configuration screen will do.

Thanks!

[Kiwi331]

Hi Dennis

Thanks for the reply.

It is continuous sampling.

I found a reason which may explain something. The same file, which I cannot run on this PC with LabVIEW 8.6, has no problem on another one with LabVIEW 2009 that I used for acquiring data.

The VI is nothing to see, which is just Read from files added with some filter. It is enough for the error to show up since the data in the file with dt=0.

I wish the new hint may help.

Best Regards,

Kiwi

[Morini]

Hi kiwi,

It seems that you are doing things in the right way. If it is okay with you, I would like to reproduce the error. I got LV 8.6 and 2009 installed and a 9205 on my desk as well.

So if you can post the code I can look more into it.

Thanks!

[Kiwi331]

Hi Dennis,

I cannot put this vi on, considering it is not small with some sub vi and some personal reasons. And I cannot make some simple vi right now since I do not have NI9205 in hand. But I think you can simply follow what I did.

Firstly, I create a vi for data acquisition in LabView 8.6 by using DAQ assist with some filtes and write to file (save the data directly from the DAQ assist).

Secondly, I copied this vi to another computer with LabView 2009 and acquiring the data.

Then, I copied the saved file back to this PC. The error shows up.

I hope it was clear of my description.

Thanks fo the help.

Fei

[Morini]

Based on your description I have created a VI and attached the logfile. I havn't encountered the -20315 error.

Please run this on your computer and let me know how it goes.

Thanks!

[Kiwi331]

Thanks, I will do it this evening, when I get the devices.

God weekend.

[Kiwi331]

Hi Dennis

I see the file of data you added is no problem, since Delta_x 0.004000. But for some reason, the data I saved with Delta_x 0.000000.

I add a small segment of the data, please take a look.

I do not know how it end up with this. But do you have good ideas of how to handle this problem, which the data has 0 dt?

I will try to see from another PC this evening again. There may be some other reasons.

Best regars,

Kiwi

[Kiwi331]

Hi Dennis

I have found the reason. The problem is that it use comma as decimal point on that computer, which definately cannot be recognized in this with dot.

However, I change the decimal point in Read from file, the error remains.

Any suggestions?

Thanks again.

Kiwi

[Morini]

Hi,

Have you tried to run the code from my previous post? Can you please tell me if the delta T is correct in the logfile?

Thanks!