can express vi handle large data

[sayaf]

Hello,

I'm facing problem in handling large data using express vi's. The input to express vi is a large data of 2M samples waveform & i am using 4 such express vi's each with 2M samples connected in parallel. To process these data the express vi's are taking too much of time compared to other general vi's or subvi's. Can anybody give the reason why its taking too much time in processing. As per my understanding since displaying large data in labview is not efficient & since the express vi's have an internal display in the form of configure dialog box. Hence i feel most of the processing time is taken to plot the data on the graph of configure dailog box. If this is correct then Is there any solution to overcome this.

waiting for reply

Thanks in advance

[becktho]

Hi sayaf

One thing you could do is to "modify" the express vi. Right click on it and select "Open front panel". Then a dialog appears - select convert. After that the front panel opens and you can modify the vi to match your needs and save it as a new sub-vi.

Thomas

[sayaf]

Thanks,

Once I change that express vi to subvi I won't get back the original express vi, hence i did not prefer trying this option. Is there any method to convert the subvi back to express...Please provide me the details/procedure.

Thanks again.

[becktho]

I don't know a way to convert it back.

Why do you want to covert it back to an express vi?

[GerdW]

Hello sayaf,

why don't you write your own subVi to process your data? Is the calculation/whatever you do with the expressVi so complicated? In my opinion the expressVis are a good choice for testing, but they have to much overhead to be used in an application. Especially when it comes to large data sets.

Message Edited by GerdW on 07-15-2005 12:09 PM

[sayaf]

Hi,

Thanks for providing details. I think there is no option left except changing the express vi to subvi & modify it accordingly. But i don't want to try this as the process is not reversible & i may reuse this express vi's in some other application. so anybody who have already converted the express vi to subvi may attach the converted subvi in reply. I am in need of Trigger & Gate.vi & Extract Portion of Waveform.vi express vi's sub vi's. I'm using LabVIEW 7.0 with Windows 2000 OS.

Thanks once again

Regards

sayaf

[becktho]

If you convert an express vi to a sub vi you can handle the sub vi as every other sub vi too - which means you can use it in any other application.

Thomas

[Philip_Courtois]

Hi sayaf,

I don't understand your reasoning for not using the "Open Front Panel" option to convert the Express VI to a standard VI. When converting the Express VI to a VI, you can save it with a new name and still use the Express VI in the same VI.

By the way, have you heard about the NI LabVIEW Express VI Development Toolkit? That is the choice if you want to be able to create your own Express VIs.
NB: Not all Express VIs can be edited with the toolkit - you should mainly use the toolkit to develop your own Express VIs.

Have fun!

[sayaf]

Thanks Everyone,
My problem got solved after converting & modifying the express vi to sub vi. Since the express vi's have lot of waveform graphs, hence it use to take lot of time to plot large data on multiple waveform graphs. I was hesitant to convert the express vi to sub vi coz i thought that the express vi once converted to sub vi will not function as express vi permanently in all applications. I was unaware that the conversion affects only that particular express vi of the application.
Thanks everyone
Regards,
Sayaf

[Philip_Courtois]

Two stars???

Did I say something wrong?

Well, I'm glad that you got it working.

Have fun!