LAVA 1.0 Content

Hello there,

Is there a way to programatically control the scrolling of a tree control.

Basically i am having a tree control and a list box with some pretty good amount of data. I would like to scroll the list box which in turn also should scroll the Tree control. Has any one done it before?

QUOTE (guruthilak@yahoo.com @ Dec 22 2008, 08:00 AM)

Hello there,

Is there a way to programatically control the scrolling of a tree control.

Basically i am having a tree control and a list box with some pretty good amount of data. I would like to scroll the list box which in turn also should scroll the Tree control. Has any one done it before?

ok i could not find a solution for this. instead i used a combination of "Scroll bar" control a "list box" and a "tree control" and used the property "top row" and "top left" to accomplish the same...

QUOTE (Minh Pham @ Dec 21 2008, 11:39 PM)

... it does have the Mouse Co-ordinate values returned which can be used but it is not the optimal way of

doing this i guess, you still have to figure out which item within the array is clicked/double-clicked and return the index so you can process a certain task for that item (eg. change the value, or pop-up msg).

LAVA CR to the Rescue.

Have a look at the Array Point to RowCol submission.

Ton

Easydaq has an USB-powered 240V relay card.

Ton

QUOTE (Minh Pham @ Dec 20 2008, 12:51 AM)

I've just figured out as well, just about to ask this:

can I use this device instead of NI ER8/16? http://www.robot-electronics.co.uk/acatalo...ay_Modules.html

According to the specs of this module it would be able to handle up to 60W, but not a 100W light bulb.

QUOTE (Minh Pham @ Dec 19 2008, 11:54 PM)

Just wondering if I can use USB6008 to turn on/off light in my room through LabVIEW?

Should I use a transformer to convert the 5V output to my desired voltage of 240 (Australia) ??

You would need to use the 5V output to control an external relay which switches on and off the 240V for the light. You can not simply pass the 5V through a transformer.

You could use he NI ER8/16 or a SSR digital module for the external relay.

I posted today a question on Stackoverflow and wow, within a few hours some good and thoughtful answers.

To promote LabVIEW I suggest all RSS readers to subscribe to the LabVIEW tag RSS-feed.

Ton

Re: Graph/chart similar to XControls

QUOTE (Aristos Queue @ Dec 18 2008, 08:23 PM)

You're not way off.

...

Finally admitted in public! I was convinced when I saw some of the bugs in the new version of the LV objects that came with LV 8+ that those would be bugs I would have wriiten if trying to implement graphs/charts/tables myself.

I have experience with XControls and LVOOP but not what I was concider a lot. They have both served well but I have never managed to combine the two in a single app.

I found working with both a good mental exercise. XControls require I think about how to do things "on a shoe string" (refs and terminals only) but still maintian good performance.

LVOOP forced me to change my model for thinking about my functions (where is the data?) but once it started to click, I found myself delivering 2.5 as many classes as the customer originally required*.

Re: "all this talk of OOP..."

I have sensed the same vibes. It feels a little like being a hockey player in a meeting for a figure skating team. "What is with all this talk of perfect figure eights? Just bash the competition into the boards and skate right pass them!" I listen in on the OOP discussions since they "help me expand my repertoire" (maybe I can do a figure eight to get around that defense man).

American Football Story

Back when the Steelers wone their first 4 Superbowls, Lynn Swann was blowing away people with his arobatic catches. It ws common knowledge here in the 'burgh that he had studied ballet as a youth.

And if the OOPish talk just becomes too much, switch over to the Dark-Side for a while. They hardly know how to spell LVOOP over there.

Ben

Yes, there is.

A summary and guideline is given in LabVIEW Bug Reporting on the LabVIEW wiki.

Ton

QUOTE (Val Brown @ Dec 18 2008, 09:25 PM)

..., unless one uses OOP etc, then one isn't a "real" programmer. BUt the essence of my frustration is with how NI has, IMO, gone off mission in dropping over the years true cross-platform development in favor of a Windows-centric approach that again, IMO, takes them off mission in additional ways.

...

Here, here!

Ton

(now about the rest of the post )

Dear friends: Do you know how to find out database quickly without entering so many university libraries and search the web again and again? Do you know what databases does a library have? You will recommend google search engine, but does it provide you enough and prcise information? No!So we made up this handbook for you guys as an index of library resource menu, for you to get to any database or journal without entering lots of university librares.

here is the handbook!

You can download the hand book here

or link:

you can go to

Could you add a piece of code?

If you want to add a screen shot I recommend the Code Capture Tool.

Ton

PS Welcome

I only dipped my toe into the pre-LVOOP versions of OOP for LV. I avoided the previous versions since "I could not attack the core" meaning I had to leave the core the way it was and therefore had to copy the data out manipulate it and then put it back. Most of my apps require high performance and I cringed at the idea of not being able to "work in-place".

I have become rather fond of LVOOP since it lets me "work in-place" and the "by-reference issue" (not built-in) is a non-issue for me since I just implemented my own version in LVOOP.

Ben

QUOTE (Val Brown @ Dec 18 2008, 01:22 AM)

....

Here's the problem with OOP and LV: which version does one use? Now one could say that, having to ask that question belies the wealth of options and that's a good thing but, on the other hand, it actually is a profound problem IMO, esp in terms of code reuse. Differing approaches (by ref vs by value, private vendor vs native LV, etc) all lead to code that can not be reused easily across differing implementations (unless I'm wrong on that) and yet isn't that supposed to be one of the many values of OOP?

If you use Endevo's toolkit with a by-ref class, you will be able to run these code without having Endevo GOOP installed (just like using an event structure in LabVIEW base), but you won't be able to adjust the Class behaviour.

This goes for most of the GOOP's implementations, using the implementation is OK, editing class behaviour might be restricted.

Ton

Have you looked at the Skype4COM documentation?

https://developer.skype.com/Docs/Skype4COMLib

It has a complete list of the classes and methods/interfaces.

QUOTE (jdunham @ Dec 17 2008, 07:22 PM)

I would love to hear any success stories, though. Anyone?

I have written an XControl for a colleague of mine in rather short time, which we later promoted to be part of our standard library, the most flattering thing he said was 'I didn't even want to look inside the XControl, it just worked'. And there is the catch-line, with XControls you are reducing a lot of code into one control with properties and method.

If you think about the graph and chart as they are currently available, think how they would be in native LabVIEW code... If you would have to do the housekeeping of data, properties, alignments, visibility of items. All these things can embraced by XControls. So my answer would be 'XControls are in', way in.

If I look at the different XControl applications to the http://forums.lavag.org/downloads.html' target="_blank">LAVA CR the diversity of coding styles inside those are good learning points, you see a lot of different styles.

Ton

My thoughts on auto-populating folders:

• I agree with the original LVProject developers to not use auto-populating folders (the feature was added after begging from the users), creation of VIs should be done with the project in mind, currently I dump all VIs in a VI folder on disk and structure them in the project.
  
• Using auto-populating folders together with libraries (XControls/classes/lvlibs) can (and will be) very confusing. (my :2cents: )
  
• I never had a need for auto-populating folders
  

However I think LabVIEW ignores hidden files/folders.

Ton

We have build XControls on top of LVClasses, where the data was sent in other VIs and representent in the XControl.

Ton

Or you could build your own, the image data returned from a read png file contains the alpha blending info, if you really want to you could write your own alpha-blending routine.

You would need to get the image behind the picture control and do your calculation but that should be doable.

Ton

QUOTE (jeffwass @ Mar 2 2005, 02:10 PM)

Does anybody know how to add new controls to a tab pane? I am working on a test-executive, and I'd like to have LabVIEW choose which graph to display, depending on what kind of data the user is taking. Ie, either chart or 2-D color graph, etc.

Also anybody know how to add/delete tab panes dynamically? There don't seem to be these options w/ the properties/methods of the tab. thanks.

A sub-panel can be used to make a tab page adapt to chaning req's. Just load the req'd FP into the sub-panel. No scripting required.

Ben

QUOTE (jdunham @ Dec 15 2008, 04:20 PM)

...you generally doing something which has never been done before ...

"and there is the rub" (Hamlet, W. Shakespear sp?)

Ben

Sorry, but you cannot do that with scripting, see this post on the JKI board how to add your own 'glyphs'.

Ton

Hi,

if you look at the code of the Code Capture Tool, there is a piece of code to do that.

However in LabVIEW 8.x you can sent any string to the OS clipboard, and I don't think there is a special 'path' type.

Ton

A control doesn't know which VIs are calling them if they are not in memory.

What I would advise is to do a mass-compile on the directory with your code in it.

What you basically do is open the VI, and save the VI. Then the changes in the typedef will be applied for you.

Ton

QUOTE (kaarthik_kaarthik @ Dec 15 2008, 06:04 AM)

Is there a method by which i can determine the knob position in the front panel is changed? in real time?

Hi Kaarthk,

what do you mean by 'Real Time' do you want to do the comparison all the time, or in LabVIEW Real Tim on an RT target?

QUOTE (kaarthik_kaarthik @ Dec 15 2008, 10:40 AM)

Could you provide a starting point for me, I have no intention of doing any type of homework, however if you allready have some code lying around please post.

Also take notice of the examples in LabVIEW for event driven programming, these will be very helpfull.

Ton

The 'Value Change' event will give you the old and new value of any type of control (including a knob).

Look at the LabVIEW Fundamentals on Event driven programming.

Ton