Wednesday, December 30, 2009

Are you a Quick Drop Enthusiast?

I think it goes without saying that I am... ;) If you are also a fan, and you'd like to talk about ideas for the feature with like-minded Quick Droppers, then you should join the Quick Drop Enthusiasts group I created last month on the NI Community website. So far, we've had some good discussions on Quick Drop feature ideas for LabVIEW 2010, some of which I have already implemented based on community feedback. I'm also planning on posting a document soon that lists all the post-release Quick Drop Keyboard Shortcuts currently available on the NI Community.

Monday, November 2, 2009

LabVIEW Performance Tips and Tricks Webcast - Wednesday, November 4th at 11 AM

This week I am giving the following LabVIEW Virtual User Group presentation:

NI LabVIEW Virtual User Groups: Tips and Tricks to Increase LabVIEW Performance and Speed

My co-host will be Todd Sierer (of An Engineering Mind fame), and I will be giving the same Performance Tips and Tricks presentation that I gave at NI Week 2009. Hope to (virtually) see you there!

Tuesday, October 27, 2009

Progress Report #1 - The Block Diagram Cleanup Experiment

As I mentioned a few months ago, I am attempting to use Block Diagram Cleanup for 100% of my diagram arrangement needs in LabVIEW 2009. I figured I might post updates every once in a while detailing my progress. So here, in no particular order, are some of my observations and impressions after heavy use of block diagram cleanup for a few months:
  • It Creates Big Diagrams - When left to my own devices, I create tight diagrams with very little whitespace. I have very quickly discovered that diagram cleanup is rather liberal with its allocation of whitespace. :) Typically this is because I've got a moderately nested diagram, and diagram cleanup doesn't quite know how to allocate space in each frame of a multiframe structure such that whitespace is minimized. I imagine this would be a rather difficult problem to solve, since it would require the repositioning algorithm to simultaneously keep track of the spacing in each frame of a multiframe structure.
  • It Doesn't Respect My Window Size - Along similar lines, the diagram gets resized and often goes past the height and/or width of the diagram window. Sometimes I have diagram windows set to a particular size for a reason, and if I were arranging the diagram myself, I would fit the diagram within those window bounds. I wish we could constrain diagram cleanup to the current diagram's window bounds.
  • It Creates Bendy Wires - I've always been very careful to minimize the number of bends in my wires, maybe because my boss was always very picky about it. In fact, he's the one who insisted "Wire Bends" be a test that shipped with VI Analyzer 1.0! Anyway, diagram cleanup doesn't seem to be so concerned about wire bends. From what little I know about the cleanup algorithm, this makes sense because the algorithm is very much concerned with node placement, and not so much wire placement (except for its strict insistence on keeping error wires straight, which I like). But if you've got nodes that you've arranged just to keep non-error wires straight, diagram cleanup will not take this into account when rearranging. Also, if you've got constants wired to things, and you've got the constants positioned to minimize wire bends, I frequently see the constant moved, and wires bent as a result.
  • It Moves My Control Terminal Labels - I like my control terminals on the sides (left for controls, right for indicators)...in fact, I added the Ctrl-Space-Ctrl-T shortcut in LabVIEW 2009 to make it easier to perform this operation in bulk for all top-level terminals on the diagram. But I've noticed my terminal labels get moved by cleanup, and it doesn't look like something that's configurable.
  • But...I Code Faster - Despite its shortcomings, block diagram cleanup allows me to code *much* faster than I do when arranging the diagram myself. I don't have any specifics, but I'd estimate that I write VIs about twice as fast as normal when I spend zero time arranging diagram objects myself.
These are my first impressions of block diagram cleanup, with just a few months of LabVIEW 2009 development (on a mishmash of small projects). But right now, I'm in the beginning stages of writing a LabVIEW Class-based prototype for a LabVIEW Scripting architecture for my current project. I hope to post more detailed observations as I become more involved in this adventure.

Friday, October 16, 2009

Quick Drop Keyboard Shortcut - Commands for "Create" Menu Options

My third post-release Quick Drop keyboard shortcut is now available on the NI Community website. This shortcut allows you to perform all the options in the right-click > Create... menu with your keyboard. You can perform these operations with one or more objects selected. For example, you could select several control terminals on the diagram, press Ctrl-Space, type reference, and press Ctrl-A, and a control reference will be created for each one, just as if you had right-clicked them individually and selected Create > Reference on each one. Check it out and let me know what you think:

Quick Drop Keyboard Shortcut - Commands for "Create" Menu Options

Friday, October 9, 2009

Quick Drop Keyboard Shortcut - Create Object from Terminal

My second post-release Quick Drop keyboard shortcut is now available on the NI Community website. This shortcut allows you to perform the Create Control/Indicator/Constant action on a terminal without having to navigate the right-click menus, simply by pressing the shortcut keys while hovering your mouse over the terminal. You can also optionally use the Quick Drop combo box to type the value of a constant created in this manner. Check it out and let me know what you think:


Note: This shortcut works on Windows and Linux, but not Mac.

Thursday, August 20, 2009

Quick Drop Keyboard Shortcut - VI Server Rename

I just posted my first post-release Quick Drop keyboard shortcut on the NI Community website. This shortcut allows you to avoid the maze of right-click submenus you must navigate whenever you want to specify the VI Server class of a Class Specifier Constant, Property Node, or Invoke Node. It also allows you to specify the name of a property or method for a Property Node or Invoke Node if you don't feel like navigating those right-click menus either. Check it out and let me know what you think:

Quick Drop Keyboard Shortcut - VI Server Rename

And look for more shortcuts coming soon!

Wednesday, August 5, 2009

Write Your Own Quick Drop Keyboard Shortcuts in LabVIEW 2009

I've always thought it would be great to define my own editor operations that occur when a certain key combination is pressed. Unfortunately, every single key combination, from Ctrl-A to Ctrl-Z, is currently taken by some operation in the LabVIEW editor. During LabVIEW 2009 development, I spoke to some of my colleagues in LabVIEW R&D to see how hard it would be to allow users to override default key combinations in LabVIEW with their own G-based features. Turns out it would be pretty tough to modify the LabVIEW editor in this manner, and nobody seemed to think it could be done anytime soon.

So I took matters into my own hands and did the next best thing I could think of, which was to define some key combinations that would perform certain editor operations while Quick Drop was visible. Once you've pressed Ctrl-Space, you're in my world now. :) So in LabVIEW 2009, there are three key combinations that I've defined:
  • Ctrl-[shift]-D - If you select some diagram objects, then press Ctrl-Space-Ctrl-D, controls and indicators will be automatically created and wired for all inputs and outputs of the selected objects. If you press Ctrl-Space-Ctrl-Shift-D, constants will be created and wired for all inputs.
  • Ctrl-R - If you select some diagram objects, then press Ctrl-Space-Ctrl-R, those objects will be removed from the diagram, but all wires that had pass-through inputs and outputs on those objects (like refnum or error wires) will be retained.
  • Ctrl-T - If you press Ctrl-Space-Ctrl-T while a diagram is open, the labels of all control/indicator terminals on the top-level diagram are moved the left/right of the terminal, respectively.
But wait, there's more! I designed this feature with everybody in mind, knowing that you might want to create your own Quick Drop shortcuts, or maybe you want to replace mine with something better. So yes, Quick Drop keyboard shortcuts are a plugin architecture, and you are free to use LabVIEW Scripting to write your own shortcuts! You'll notice that the following folder now exists in LabVIEW 2009:

[LabVIEW 2009]\resource\dialog\QuickDrop\plugins

Inside this folder are d.vi, r.vi, and t.vi. Those are the VIs that define the Ctrl-[shift]-D, Ctrl-R, and Ctrl-T shortcuts in Quick Drop. If you want to write your own shortcut (let's say it's Ctrl-E), start with resource\dialog\QuickDrop\QuickDrop Plugin Template.vi, save it as e.vi in the plugins folder, and now you have a Ctrl-Space-Ctrl-E shortcut!

As I get time in the coming months, I plan on posting new shortcuts to the NI Community that I didn't quite have time to squeeze into the LabVIEW 2009 release.

Tuesday, July 21, 2009

My NI Week 2009 Plans

I was inspired by Christina's NI Week post on her blog to post my tentative NI Week 2009 schedule, in case anybody is wondering where I'll be during NI Week. After each morning's keynote, I'm planning on helping out in the What's New With LabVIEW hands-on sessions at 10:30 in Room 18C each morning. After that, here are my plans (which are subject to change based on hunger, long conversations about LabVIEW, impromptu VI-writing contests, challenges from Guitar Hero robots, and many other possible NI Week-sanctioned distractions):

Tuesday
  • LabVIEW Experts Panel: 12:00, Technology Theater. Maybe a LabVIEW Artisan will be allowed to hang out with LabVIEW Experts?
  • Hack Your Car with NI-CAN: 1:00, Room 15. I've driven my car for months with the Check Engine light on, with no (visible) ill effects. I sure would like to be able to figure out why that light is *really* on.
  • LabVIEW Scripting: 2:15, Room 16B. I'll be there mainly to help answer any specific scripting questions that might come up.
  • New Software Engineering Tools in LabVIEW: 3:30, Room 16B. I honestly don't know what we're presenting on here, and I'm curious to find out.
  • Challenge the Champions: 5:00, Technology Theater. I wrote some of the questions for this year's event (and not a single one of them has to do with Express VIs!).
  • LAVA BBQ: 8:00, Stubb's. I *think* I can make it this year, but I'm not sure yet.
Wednesday
  • Past, Present, and Future of Robots: 1:00, Room 17B. The dude that runs the Roomba company is presenting this one.
  • Tools and APIs to Build on the LabVIEW Platform Hands-On: 2:15, Room 18C. I helped write a lot of the initial content for this, so I'm interested to see how it turned out.
  • Memory Management in LabVIEW: 3:30, Room 16B. Dan H. is one of the foremost experts on the guts of LabVIEW. I've seen some of the content for this presentation and it should be great.
  • Tips and Tricks to Speed LabVIEW Development: 4:45, Room 16A. I'm presenting this one, so I should probably show up. For those of you who came to my performance tips and tricks presentation at NI Week 2008, I've got a brand new set of tips and tricks up my sleeve this year. Don't miss it!
Thursday
  • LabVIEW Coding Challenge: High Noon, Technology Theater. Who dares challenge me after my resounding victory at NI Week 2008? You have all had a year to practice with Quick Drop, so no more excuses! I'm looking at you, Jim. :)
  • Web Services in LabVIEW: 1:00, Room 16B. I must admit, I know a lot less about web services than I should.
  • Improving the LabVIEW Upgrade Experience: 2:15, Room 16A. I'm always telling people about great new LabVIEW features, so I should probably be familiar with issues people have when trying to upgrade so they can use those new features.
So if you made it this far, I have a couple of other things to mention about NI Week 2009:
  • I plan on twittering frequently (with my new iPhone!) about what I'm doing and cool stuff I'm seeing at NI Week 2009. Follow me at http://www.twitter.com/dnatt if you don't already.
  • The NI Week program incorrectly lists me as the presenter for Beyond the Basics: LabVIEW Debugging Techniques on Tuesday at 2:15. Actually, Tycho C., the author of the Desktop Execution Trace Toolkit, is giving that presentation.

Friday, July 17, 2009

The Diagram Cleanup Experiment

For many years now, I've taken pride in the appearance of my LabVIEW diagrams. One of my first tasks when I joined LabVIEW R&D several years ago was to rewrite the LabVIEW Style Guide, and more recently, I was very much involved in the reviews of Peter Blume's The LabVIEW Style Book. I cannot claim style perfection, but I can say that you would have to search pretty hard in all the code I've written over the years to find backwards wires, overlapping objects, uncommented code, or any other style transgressions.

However, that clean code doesn't come without a cost...a cost of time. It takes time to perfectly align objects, to minimize space to achieve optimal compactness, to align control terminals on the left and indicator terminals on the right. My kindred spirits in LabVIEW style know what I'm talking about here.

Speaking of time...for the past year, I've been enjoying how much time I've been saving with Quick Drop. I can safely say that the most constrictive bottleneck on my LabVIEW programming speed--palette navigation--is no longer an issue. But seeing as I'm always looking for ways to write more code in less time (which translates into more features for you!), I very quickly became aware of the next biggest bottleneck--clean diagram arrangement.

So I'm going to embark on a journey with LabVIEW 2009...one which is undoubtedly fraught with peril, but should ultimately benefit all LabVIEW users. I am going to throw my current method of incremental diagram arrangement out the window, and rely 100% on Diagram Cleanup to do the job for me. The way I see it, we've got a feature here that is supposed to give us clean diagrams. It's also going to have some pretty nice improvements in LabVIEW 2009. So instead of ignoring this great feature that has tons of potential, I'm going to use it, recognize its shortcomings, experiment with its customizable settings, and file CARs to make it better. I envision a day, hopefully not too far off in the future, where we can spend our programming time focusing entirely on programming, and not being distracted by aesthetics.

Friday, June 12, 2009

LabVIEW Scripting Tip #3: How to Handle References

Once you get past the really simple scripting apps, you'll quickly discover that your scripting VIs can become unwieldy at a moment's notice, and this is primarily due to how many VI Server references you have to deal with in a complex scripting app. Here now is a list of things to keep in mind when dealing with a plethora of scripting references all over your diagram.
  1. When to Close References - For every single VI Server reference type *except* VI and Application, it's fine to close the reference as soon as you're done with it. I've seen people write scripting VIs before where they thought they needed to keep each "parent" reference open as long as they were using a child reference. This is not the case. Check out this sample diagram, which is getting the first tunnel it finds on a Case Structure and determining if it is an output or an input tunnel:







    This code will work, but those wires don't need to span the entire diagram just to be closed later. You can imagine these wires could get very long as the complexity of your scripting code increases. Instead, take an approach like this:







    Here, we are closing the references as soon as we're done with them. The diagram looks cleaner, and we don't have to worry about passing really long wires around. Also, note the trick I'm doing with the array of Tunnel references. Often in VI Scripting, you'll have an array of references, but you're only interested in one of those references. In these cases, you can use the Delete From Array function to pull out the one you're interested in, and close all the rest.
  2. Comparing References - If you are trying to compare two references to see if they refer to the same object, you can simply use the Equal? function. Similarly, if you have an array of references, and you want to search that array to find the index of a particular reference, you can use the Search 1D Array function. Even though two references to the same object may have different flattened U32 refnum values (as can pretty easily be seen with the Type Cast function), using the comparison functions in LabVIEW will compare the actual objects those references refer to, and not the numeric refnum values, when performing the comparison.
  3. Checking Reference Type - Many times you'll have a reference to an object, and you'll want to figure out what type of object it is. You may be inclined to read the Class Name property of that object, but this approach can cause problems. For example, let's say you have a reference to a Node, and you want to see if it that Node is a member of the Structure class (Case Structure, While Loop, For Loop, etc.). So you read the Class Name property of the reference and see if it equals "Structure". Well, this approach will never work, because the Class Name property always returns the most specific class name of the object...so it would return CaseStructure, WhileLoop, ForLoop, etc. Instead of using the Class Name approach, you can use the To More Specific Class function and check the error output:






    In this case, as long as the Node is any type of Structure, the class conversion will succeed.
Does anybody have any additional tips for dealing with references when programming VI Scripting applications? Let's hear them!

Friday, June 5, 2009

LabVIEW Scripting Tip #2: Supporting Undo

One of the great things about LabVIEW Scripting is that we can implement tools that perform actions in the LabVIEW editor. There are already several utilities posted on LAVA along these lines, along with the hopefully-soon-to-be-released JKI Right-Click Framework. Not to mention current and future shipping LabVIEW features.

In order to give your scripting-based utility equal footing with built-in LabVIEW features, though, you need to make sure anything you do with scripting can be undone or redone by the user. Thankfully, there is support in scripting for setting up Undo/Redo transactions, as illustrated by this screenshot:



Here are some details on each of the methods shown in the screenshot:
  • Transaction.Begin Undo - Call this method before you start your scripting operation. The "Name" input is the text that you want users to see next to the Undo/Redo options in the Edit menu:











    After calling Begin Undo, you will do all the scripting code you need to do for whatever editor operation you are performing. While doing your scripting, you need to keep track of a boolean, or some sort of flag, indicating whether or not you actually want to complete the Undo transaction, so you can make a decision between the following two methods.
  • Transaction.End Undo - Did everything script ok? Assuming you didn't get any errors, and that your scripting code actually did change something on the target VI, you need to end your Undo transaction. This actually commits the scripting action to the target VI, and creates the Edit > Undo option in the menu with the Name you specified on Begin Undo.
  • Transaction.Fail - Did an error occur during your scripting? Or did your scripting code not actually change anything? If either of these is the case, you probably want to Fail the transaction. This means that the transaction is not committed to the target VI, and that no new Undo option is added to the Edit menu. Notice that in my screenshot, I do not wire the error up to the Transaction.Fail method. This is because, if an error occurred in my scripting, I still want the Fail method to execute so it cancels the transaction.
If you decide not to wrap your scripting operations with these transaction methods, there are two significant consequences. First, and most obvious, is that users will not be able to undo whatever scripting operation you have performed. Second, and more severe, is the fact that a scripting operation that is not wrapped with these transaction methods can clear the existing Undo stack of a VI. So if you are developing a first-class scripting utility with any sort of integration into the LabVIEW editor, make sure to take these simple steps to make your operations undoable/redoable.

Wednesday, June 3, 2009

LabVIEW Scripting Tip #1: The Power of Traverse

This blog post is the first in an as yet unknown number of posts detailing some useful tips I have on LabVIEW Scripting.

If you're ever examining VIs to find objects of a particular type, then you definitely want to check out the following utility VI:

[LabVIEW]\vi.lib\utility\traverseref.llb\TRef Traverse for References.vi

This VI will return references to all the objects of a given class that reside within the panel, diagram, or a user-defined object in a VI. The traversal is recursive, so it will find objects nested within other objects. Here's a simple example that finds all the Case Structures on a diagram:









We specify a target of "BD" (for Block Diagram) and a class name of "CaseStructure", and we're good to go. Note that you can also traverse the front panel for objects by specifying a target of "FP". And if you want to traverse a specific object (i.e. find all the clusters that reside within a particular Tab Control on the front panel), then specify a target of "Other" and pass in a reference to the Tab Control to the "Other Refnum" input.

You may wonder why I recommend using this VI, when there is already a scripting property called AllObjects[] for the Diagram class (and a similar property for the panel). Well, that AllObjects[] property does not recurse into container objects. So to completely search a diagram for objects, you would need to get the AllObjects[] property, figure out which objects are containers, separate those objects out, get the container diagrams, do an AllObjects[] on them, etc. etc. This is certainly doable, and I'm guessing people have already written VIs that do this...but in my experience, using the Traverse VI is much, much faster than trying to recurse the entire diagram with AllObjects[].

This traverse VI is used extensively in the VI Analyzer Toolkit, since we are often looking for specific objects on the diagram that we need to examine. And if you know the label of a specific object you are looking for, then you can use the TRef Find Object By Label.vi in that same LLB, which is basically a wrapper for TRef Traverse for References.vi, but it goes an extra step and reads the labels of each found object until it finds the one you were looking for.

Just to give you an idea how useful this VI can be, TRef Traverse for References.vi originally shipped only with the VI Analyzer Toolkit 1.0 when LabVIEW 7.0 released. However, once it got to the point that about a dozen internal groups at NI had asked me for a copy of the Traverse VI so they could ship it with their products, I decided it would be best for all of us if a single copy of the VI shipped with core LabVIEW, which it has since LabVIEW 8.0.

Friday, May 29, 2009

Writing VIs with VIs

LabVIEW Scripting officially released today. In case you've been living under a rock (or you never visit LAVA), LabVIEW Scripting is an (until today) internal LabVIEW feature that allows you to write VIs that create, modify, and inspect other VIs. In my 7+ years in LabVIEW R&D, I have worked on *a lot* of products that utilize scripting...VI Analyzer, Simulation Interface Toolkit, and the Ladder Editor, to name a few. I'm really excited that I'll now be able to discuss scripting with the LabVIEW community, since it's been such a big part of my job for so long.

If you're looking to get your feet wet with scripting, I think the best way would be to write a plug-in for the JKI Right-Click Framework. With this framework and LabVIEW Scripting now available, we can write all those little features for the LabVIEW editor that we've always wanted. I know I plan on writing some plug-ins as soon as the framework is available.

Another benefit of the scripting release is that I can post utility VIs to the NI Forums that utilize scripting *without* having to password-protect their diagrams anymore. :)

Monday, May 4, 2009

2009 Reasons I Love the New LabVIEW Versioning Scheme

Ok...maybe I don't have *quite* 2009 reasons, but I am a big fan. In case you hadn't heard, the next version of LabVIEW will be LabVIEW 2009. This wasn't a big secret or anything...the new versioning scheme was revealed when we announced the beta. Going forward, each LabVIEW release will simply be versioned based on the year of its release. In no particular order, here's why I like this idea:
  • It's immediately obvious how old of a LabVIEW version we're dealing with. As it is now, I can't even remember what year LabVIEW 7.0 released (I just looked it up...2003 apparently).
  • We become more consistent with other software out there that is moving toward year-based versioning.
  • Most toolkits will also be adopting the year-based versioning. So now we don't have to remember that Report Generation Toolkit 1.1.3 only works with LabVIEW 8.6, or that VI Analyzer Toolkit 1.1 only works with LabVIEW 8.0, 8.2, and 8.5. Going forward, Report Generation Toolkit 2009 will work with LabVIEW 2009, VI Analyzer Toolkit 2010 will work with LabVIEW 2010, etc.
  • The internal version of VIs saved in LabVIEW 2009 will be 9.0. So it's pretty convenient that the year '2009' lined up with that.
  • This one is minor, but up to this point, we always had a code name for LabVIEW releases in R&D. 8.6 was Saturn, 9.0 is Orion. (Again, not a big secret here...I figure if one of our VPs can talk about the code names, so can I). So when you'd talk to somebody about the release, half the time they'd use the code name, and half the time they'd use the version. Now we'll just be referring to each version by the year of its release...no more code names. Trivia question: Any non-NIers out there know the code names for prior LabVIEW releases?
  • We won't be using this versioning scheme for drivers. Again, I think this makes sense, because a lot of drivers release multiple times per year. Plus, I don't think I've seen any other driver developers out there use year based versioning. It appears to be primarily for application software.
  • I've noticed that people have interpreted LabVIEW version numbers in very different ways over the years. Some people think "x.0" releases are unstable and won't touch them. They prefer to wait for the much more 'stable' "x.1" release. Other people think "x.0" releases are the only ones that have any worthwhile new features, and the "x.1" releases are only 'minor updates'. Truth is, every LabVIEW release (barring x.y.z maintenance releases) is a major release. I've found must-have features in every LabVIEW version since I started programming LabVIEW. I think year-based versioning will help us all gain a more unified vision of what to expect out of a yearly LabVIEW release.
Despite all these pros, I'm sure other LabVIEW users out there (like the ones who responded to the beta announcement thread I linked above) feel differently. What do y'all think about LabVIEW 2009?

Friday, April 17, 2009

Input Devices and LabVIEW Programming

I came across this post on the NI forums today with a screenshot of a cool office setup. One thing that caught my eye was the Ergodex DX1 input device. I read up on it, and was impressed by the price ($150 seemed relatively inexpensive), but was disappointed with the lack of Vista support. I would have seriously considered getting one of these, just to see how I could use it to speed up LabVIEW programming...but my new dev machine at work is a Vista box, so it's a no go. I was thinking it would be great if you could have one of those buttons be mobile, and essentially be a mouse, but I don't get the impression that's supported behavior, judging from their online documentation.

I've been thinking lately of ways to speed up LabVIEW programming, and computer interaction in general. There are very expensive eyeball-tracking devices that are primarily marketed toward disabled individuals, but nothing that I know of for the general populace at an affordable price. I've always thought that, short of mind reading, the movement of the eyeballs is probably the fastest potential way to control a computer. However, I also imagine the accuracy required in the optical hardware is probably what makes the current offerings so expensive. But as our screens get bigger, we'll be taking more time to accurately move the mouse to specific locations on the screen. Someday (maybe far off in the future), I think we'll come up with some more efficient interfaces.

Anyway, I always think about these ideas in the context of making LabVIEW programming faster and easier, but I think they would benefit the computer world at large. Sometimes I think it would be cool to prototype new input devices and gauge their potential, but my Mechanical Engineering skills are far too rusty at this point.

Monday, March 23, 2009

How Do You Like Your Nuggets Served?

I've been receiving some requests lately regarding delivery of my weekly LabVIEW nuggets...some people want emails, some want RSS feeds, and some want a static document they can search. I hope the following solutions will satisfy all your varying nugget appetites:
  • Email - To receive an email notification when I post a new nugget, visit the Darren's weekly nugget thread on the NI Forums. Assuming you are logged in with your NI Forums ID, you can click the Thread Options button and choose Add this Thread to my Subscriptions. Note that other NI Forums users will occasionally post nuggetish links to this thread, but most of the time, it's me posting links to my weekly nuggets.
  • RSS - I created a weekly nugget blog on the NI Community website. The feed URL for this blog is here, so if you subscribe, you'll get notified in your favorite RSS reader whenever I post a new nugget.
  • Static Page - I also created a static document on the NI Community website that contains links to all my nuggets, and a short description of each nugget. You can use this page if you want to search to see what topics I've posted nuggets about throughout the years.
Is there another nugget distribution mechanism you would prefer? Let me know.

Thursday, March 19, 2009

Why Are You Still Using Loops in Your Functional Globals?

Are you still creating Functional Globals (a.k.a. LV2-style globals) that look like this?












If you're programming in LabVIEW 8.5 or later, do this instead!












In LabVIEW 8.5, Feedback Nodes gained the ability to live on the top level diagram of a VI... no loop required. This feature gives us the identical functionality of a single-iteration loop with an uninitialized shift register. And let's be honest here...the uninitialized shift register on a single-iteration loop is kind of a hack.

Not only does the Feedback Node clean up our diagrams, but it is slightly faster (sometimes by about 5-10%) than a loop with an uninitialized shift register. This is largely due to the removal of loop overhead.

So get over your Feedback Node (and backwards wire) hangups like I did and make your functional globals more efficient!

Friday, March 6, 2009

LabVIEW on a Netbook...It's Not That Bad!

In my last blog post, I mentioned I had an extra motive for writing the Bulk Controls and Indicators VI. I wanted to write a moderately-sized VI with my new Acer Aspire One netbook. I got the fully-loaded one: Windows XP, 160GB HDD, 6-cell battery (6+ hours!), and it was only $330 on amazon.com (mine is the blue one, just like the picture). I've always loved small laptops (my previous was a Toshiba Satellite U205), and I originally bought this netbook for my wife. But she said it was too small, so she's getting my Toshiba and I'm taking the Acer. The reason for the new laptop, by the way, was that my wife's original Dell Inspiron b130 suffered catastrophic mechanical failure in the form of the screen becoming detached from the base.

I really, really love this thing. Its only drawback is inherent to its design...the maximum screen resolution for the 8.9" model I got is 1024x600. (There was another drawback regarding a slow network connection, but this link helped me solve it). As soon as I got it, I installed LabVIEW to try writing some VIs. I was worried at first about performance, but this laptop is really snappy...a non-initial launch of LabVIEW only takes 9 seconds (with Load Palettes at Launch enabled), and Quick Drop is instantaneous (that's been my editor benchmark of choice since 8.6 released). My next worry after performance was LabVIEW's usability on a small screen. Here's what I noticed:
  • The Getting Started Window doesn't fit on the screen (I hope somebody's Eyes are reading this). I wasn't too surprised by this, since our minimum screen resolution that we usually assume when designing UIs in LabVIEW R&D is 1024x768. Thankfully, the 'X' in the corner was still visible, so it wasn't too much of an inconvenience.
  • Apparently when you create a New VI, the size of the VI created is proportional to the screen size. I never really noticed this before until comparing the size of a new VI on the netbook to the size of a new VI on my 22" widescreen on my dev machine at work... :)
  • This isn't really peculiar to netbooks, but I quickly reminded myself how sloooow I am at programming LabVIEW with a touchpad. I'm planning on getting a nice wireless mouse, but for writing this VI, I used the free Acer mouse they sent me with the netbook.
  • Whenever you ctrl-drag in empty space to create diagram space, it's much more difficult to only drag in one direction (usually left-right for me), I guess because the lower resolution of the screen makes for larger relative mouse moves? I've filed a suggestion in the past that a ctrl-drag have a few pixels of slop on either side for growing only in one direction, but we haven't seen it yet...
So all in all, a pleasant experience. I don't think I'd be able to develop 8 hours a day on such a small screen. But for demonstrating something in LabVIEW during a discussion at work or NI Week, or for knocking out a quick VI for the NI Forums, LAVA, or my blog, I think it will be perfect.

Thursday, March 5, 2009

Bulk Creation of Controls and Indicators

In my previous blog post, Jason commented that it would be nice to have a utility that will create controls and indicators on diagram objects in bulk. I thought that was a good idea, and I decided to write a VI that gets us pretty darn close...it's not quite a right-click option, but it's as close as I can get without getting a C-monkey to modify the LabVIEW source code for me, and without having plug-in VIs yet.

So put this VI in [LabVIEW 8.6]\project and restart LabVIEW. You'll now have a Tools > Create Controls and Indicators menu option. Select a few block diagram objects, then choose this menu option. It will create controls and indicators for any terminals of the selected object(s) that aren't already wired to something. This transaction is undoable/redoable as well.

I hope this VI is useful to people. I also had another motive for writing it, but you'll have to wait until my next blog post to find out what that was.

Tuesday, March 3, 2009

A Good Use for Block Diagram Cleanup

One of the big new features of LabVIEW 8.6 is Block Diagram Cleanup, a way to instantly rearrange block diagram contents to make them look "better". In fact, I demoed this feature briefly during my NI Week 2008 keynote appearance. In practice, however, I find that I don't really use the feature all that much. Keeping the diagram clean as I write code has been an integral part of the way I do my job for the past several years, and honestly, if I run Block Diagram Cleanup on my clean code, it makes it considerably less clean. I know many other advanced LabVIEW developers who feel the same way.

Lately though, I have discovered a perfectly valid niche use case for this feature. One of the great things about LabVIEW is how easy it is to write "throw away" code...you know, that simple prototype VI that you write just to test an idea, or that debugging VI that helps you quickly unit test something you're working on...or even the VI where you just drop a single function and wire a few things in to double-check that it works the way you expect (I do this with Match Pattern about once every few months). Well, I tend to write throw away code very quickly, with no regard for "cleanliness". It's these throw away VIs that are the perfect candidates for Block Diagram Cleanup...with a single Ctrl-U, my code becomes considerably more clean than it was before, when I was slinging objects left and right with Quick Drop and reckless abandon. And even though it's throw away code, it's still easier to understand and modify (before I throw it away) if it's clean.

Here's an example "before and after" of one of these situations. In this case, I wanted a VI that displayed every single value in my LabVIEW Class data...in this case, there were several subclasses that contained arrays, so a simple probe wouldn't let me see multiple array elements at once...so I basically wrote a huge "probe" VI that displayed a bunch of these arrays, with several elements expanded. This VI was purely for debugging, and would be of limited utility once I got all my class data straightened out...in other words, it was a "throw away" VI. So I slopped it together, then I cleaned it up. Although not perfect, the cleaned up version is much easier to understand (sorry for all the Wite-Out...these classes pertain to features that have yet to be released):

Before:


After:


I understand that this might be a pretty limited use case, but who knows...maybe I should get my feet wet with the feature now, in the event that it gets a lot better in a future LabVIEW version?

Tuesday, February 24, 2009

My Tools > Options Settings

I've seen many people (myself included) make vocal arguments in favor of their own personal Tools > Options settings. Ultimately though, most of these settings come down to personal taste. Here now, are my personal preferences regarding many frequently-discussed Tools > Options settings, along with an occasional anecdote. Keep in mind that you can simply copy your LabVIEW.ini file from one LabVIEW installation to another to preserve these settings (so you don't have to go through and check/uncheck a bunch of options with every new LabVIEW install):
  • Front Panel: Connector pane terminals default to Required: CHECKED - I really love this option, which was added in LabVIEW 8.5. There were so many times in the past when I was working on an app, and I'd add inputs to a subVI but forget to wire them up in the calling VI, then spend several minutes debugging before I figured out what I'd done. Also, this option is smart enough to ignore error input terminals, leaving them as Recommended.
  • Block Diagram: Enable automatic error handling in new VIs: UNCHECKED - I understand that this option exists for the benefit of new LabVIEW users, but for the rest of us, it's just WRONG.
  • Block Diagram: Enable automatic wire routing: UNCHECKED - I've tried this option a few times, but I think my manual routing of wires produces much cleaner diagrams.
  • Block Diagram: Enable auto wiring: CHECKED - I remember when I worked in the AE department and hadn't yet joined LabVIEW R&D, I attended a "demo day" on the LabVIEW floor where all the LabVIEW developers were showing off the features they were working on. When I saw this one (called "wire kissing" at the time), I thought it was way cool. And I've been a fan ever since, especially for automatically wiring error clusters. Note that when you drop objects with Super Quick Drop, auto wiring does not occur...but it's a small price to pay in order to be able to code at lightning speed...
  • Front Panel/Block Diagram: Labels snap to preset positions on terminals: CHECKED - Another one of my favorites...this one was under my radar until it just appeared one day in a build of LabVIEW 8.0. My boss is a bigtime pixel-counter, so it was nice to have a really quick way to drag a label into the correct spot.
  • Block Diagram: Place front panel terminals as icons: UNCHECKED - In LabVIEW R&D there is one extremely fierce advocate of keeping this feature checked by default. He shall remain nameless. If he wasn't around, though, we probably would have changed this option long ago (I'd personally prefer that we just remove it altogether). Looking at the big picture, though, it's probably worth having this option checked by default and keeping this guy around. :)
  • Block Diagram: Place structures with Auto Grow enabled: UNCHECKED - I take pride in the way my diagrams look, and I like having 100% control over how they look. The thought of dropping a function in a nested structure, and having a bunch of crap all over the diagram move around as a result...it's a little too much for me to take.
  • Block Diagram: Show red Xs on broken wires: UNCHECKED - Originally this feature did not have an entry in Tools > Options...you either lived with it, or found out what the INI token was to disable it. I hated the feature so much, I demanded a Tools > Options checkbox. What I didn't know was that, at the time (LabVIEW 7.0), the Block Diagram page in Tools > Options was completely full, and required a complete reorganization to fit in this new option. You should have seen the sad look on the unnamed developer's face (yes, the same one who likes terminal icons) when he realized that he was going to have to add my option. For those of you who hate red Xs, you're welcome.
  • Block Diagram: Show dots at wire junctions: UNCHECKED - I just think they're ugly.
  • Block Diagram: Show constant folding of wires/structures: UNCHECKED - The fuzzy wires make my eyes hurt. And I never really saw any benefit to knowing when constant folding is taking place. Seemed like more of a novelty than a utility.
  • Block Diagram: Auto-insert Feedback Node in cycles: UNCHECKED - Don't get me wrong, I really like Feedback Nodes as a replacement for Functional Globals. But every once in a while I'd be wiring up some stuff in a loop, and connecting wires to each other while re-wiring things, and somehow my broken wires would turn into Feedback Nodes, and that freaked me out. So now I only get Feedback Nodes if I explicitly drop them myself.
  • Alignment Grid: Everything: UNCHECKED - I don't like the grid. It makes things look too noisy.
  • Controls/Functions Palettes: Palette Loading: LOAD PALETTES DURING LAUNCH - As you hopefully know by now, this enables Quick Drop to be instantly usable on its first use, at the expense of a slightly longer LabVIEW launch time.
  • Environment: Maximum undo steps per VI: 99 - I've never seen any performance problems with cranking up this setting.
  • Environment: Skip Getting Started window on launch: CHECKED - Since my LabVIEW launch time is a little longer for Quick Drop, I figure I can save a second or so if I don't have to load the GSW...I never really used it for anything special that I couldn't access from a new VI's File menu.
  • Environment: Lock automatic tool selection: UNCHECKED - I'm a big fan of the Auto Tool, but I do like being able to press Tab, like the good ol' days, if I really need to.
I may have missed some here and there, but that's good for a first pass. Commence arguing!

Sunday, February 8, 2009

LabVIEW Certification: Preparing for the CLA

NOTE: As of July 2010, the CLA Exam has changed, rendering most of the information in this blog post obsolete. For more information about the changes, see my Changes to the CLA Exam post.

When I embarked on the LabVIEW Certification journey, I knew I was going to go all the way. So after I passed the CLD, I immediately began preparing for the Certified LabVIEW Architect (CLA) Exam. According to the CLA webpage, there are several areas of competence associated with the exam, including "mastery in architecting LabVIEW applications", "effectively utilizing project and configuration management tools", and "experience of approximately 24 months in developing medium to large LabVIEW applications".

One of the things I discovered almost immediately was the simple lack of CLA preparation materials. The CLAD had the webcast, the prep guide, the LabVIEW Fundamentals Exam and at least one practice exam that I could find. The CLD had the webcast, the prep guide, and three practice exams. The CLA, however, had no practice exams available. In fact, the only preparation material available on the NI website is the CLA Exam Preparation Guide. I highly recommend reading this preparation guide, as it is the only available "official" source of information on the exam. Also, after taking the exam, I now understand why there isn't much in the way of preparation materials...more on that later.

So once I read the CLA prep guide, I knew the test would consist of a written component worth 40% and a coding component worth 60%. The written component of the test consists of short-answer questions pertaining to project planning, and the coding component consists of developing an architecture for the actual application.

Now one of the other things mentioned in the CLA prep guide was that the LabVIEW Advanced course offered by NI covers a lot of the material tested on the CLA. Since I work for NI, it was easy for me to get my hands on a copy of the LabVIEW Advanced course and check it out. Sure enough, it covered a lot of the topics listed in the CLA prep guide. I don't think reading through this course was a crucial step in my passing the CLA, but it certainly didn't hurt.

Honestly, the best preparation I did for the CLA was the simple act of being a full-time LabVIEW developer for the past seven years. Topics like writing specification documents, source code control, and designing architectures have simply been part of my job. If you have been part of a multi-developer LabVIEW team for any length of time, then a lot of the topics in the CLA exam should come naturally to you. If you're brand new to LabVIEW, or if you've only been developing small-scale applications, or if you've been flying solo without a formal software design process, this certification may not be for you. There's not really any way to "practice" these sorts of things right before the test, which is why it makes sense to me (now) that there isn't much prep material available. Nevertheless, I offer the following tips for anyone attempting the CLA. These come from my own personal experiences in preparing for and taking the exam:
  • Since the written component of the CLA is worth 40% of your grade, and the coding component is worth 60%, I recommend spending your time in a similar proportion. My personal times ended up being 1.5 hours on the written and 2.5 hours on the coding.
  • For the written component of the exam, many of the questions ask for a certain number of short responses, i.e. "Give 3 problems you might encounter if...". For these, I recommend a bulleted list of one sentence (or maybe two) for each answer. Keep the answers concise. Writing a paragraph for an answer that could be written in a sentence doesn't get you any extra points, and only wastes precious time (and for me, time was very precious...see below).
  • In the coding component of the exam, you should pretty much follow the same guidelines you followed when writing the code for your CLD exam (see here for my advice on the CLD). Document your code, use good style, know your design patterns, etc. etc. Obviously you probably won't have as much time to do things like document every front panel control of every VI you write, but do the best you can given the time you have.
  • Speaking of time, here is the most important advice I have to offer. Unlike the CLD (which I finished in 2.5 hours), I was severely time-crunched on the CLA. To give you an idea how time-crunched I was, I realized when I had 45 minutes left that I still had about 2 hours worth of coding to do. Oops! It turns out that I did not heed the advice given in the CLA prep guide, which was that I was not supposed to write a fully-functional application! This is very, very good advice. The application specifications given in the CLA for a functional application would be relatively easy for me to complete...in about 6 hours. Unfortunately, I had 2.5 hours to write code for the CLA. And as I so often do when I write LabVIEW code, I got into "the zone", where I started writing lots of subVIs to implement specific, non-essential details of the application, before I had fully completed the overall architecture. When you take the CLA, do not do this! Focus on the architectural patterns, focus on the design for your plugins, focus on the data sharing mechanisms you use, but do not just start fully implementing non-essential subVIs! For example, I spent about 30 minutes writing a nifty little algorithm for part of my plug-in architecture. This was a bad idea. What I *should* have done was write the interface for the VI (i.e. the conpane and typedefs), and included a 1-2 sentence comment on the diagram describing how the algorithm would work. Now thankfully, I'm a pretty fast coder, so once I realized I was running out of time, I kicked it into hyperdrive and got some code written that (apparently) was passable. But I wouldn't wish that 45 minutes worth of monumental stress on anybody! Not even a text-based programmer!
So in summary, if you're taking the CLA, good luck! Make sure you've actually architected something in LabVIEW before. The LabVIEW Advanced course has some good stuff in it if you're looking to go that extra mile in preparation. And above all, your application architecture should trump any coding details you may be tempted to implement. Trust me on that...

Wednesday, January 28, 2009

LabVIEW Certification: Preparing for the CLD

After I passed the CLAD, I decided to try the Certified LabVIEW Developer (CLD) exam. According to the CLD webpage, the purpose of this exam is to "demonstrate experience in developing, debugging, and deploying medium to large LabVIEW applications."

To prepare for the CLD, I first watched the CLD webcast to get a good summary of what to expect on the exam. It turns out the material in the CLD webcast was very similar to the material in the CLD Exam Preparation Guide, but I still read through the entire document to make sure I was familiar with all the areas of competence associated with the exam.

I spent the bulk of my preparation time working through all of the sample exams that were available. My main purpose in working through the sample exams in their entirety was to ensure I wouldn't have any issues with the 4-hour time limit of the CLD. Thankfully, I completed the sample exams and the actual CLD with plenty of time to spare. I strongly recommend that anyone planning to take the CLD work through all the sample exams, not only to assess your coding time, but also because the sample exams are very similar in nature to the actual CLD.

Many people have posted CLD suggestions and tips on the NI Forums and the LAVA Forums. A search of "CLD preparation", or simply just "CLD", will probably yield some useful results. Here's a list of what I feel are the most important points to know before going in for the CLD:
  • I can't stress enough the importance of taking all the sample exams and timing yourself. If you're unsure about your programming, post your resulting app to the NI or LAVA forums and ask for some general "How did I do?" feedback.
  • When the exam begins, spend a few minutes customizing the LabVIEW environment to match your typical setup. For me, this included things like adding my most common Quick Drop shortcuts, turning off structure auto-grow and red Xs on broken wires, etc. (check out this blog post where I talk about my favorite Tools > Options settings). You'll make up those few minutes many times over during the exam when you're not continually slowed down by environment settings with which you're not familiar.
  • Documentation is a huge part of your CLD score, and it is one of the easiest areas to maximize points. Set a description and tip on every front panel control and indicator. Set a VI description on every VI you write. If you use the LabVIEW Project, set a description on all non-VI items in your project (like .lvlibs). Place comments *everywhere* in your diagram, describing your functionality in a concise way. Make sure to document the diagrams in different cases and loops. It is also a good idea to label long wires and wires associated with shift registers.
  • Make sure your application is functional before submitting it. It's probably not a bad idea to save all your VIs and close everything down once you're done, quit LabVIEW, restart LabVIEW, open your VI, and make sure it runs correctly. This will eliminate the possibility that you've got non-default values in controls that won't persist after a restart, or that you've got changes to VIs in memory that aren't committed to disk, etc.
  • For the CLD, the functionality of your application should trump the complexity of any architectures you select. If you think you can control your CLD app with a simple state machine, and that's a programming structure you're comfortable with, then use a simple state machine. Don't choose an overly complicated architecture if you're not comfortable using it.
  • Make typedefs out of any clusters or enums you create for your applications.
  • Create a non-default icon for every VI you write (I'd recommend this for .ctls and .lvlibs as well, although that's a pretty low priority). Simple black border, white background, black text icons should be fine. Don't waste time drawing pictures of DAQ boards or librarians in your icons.
  • Write clean code. You can lose points for bad style.
  • If you're running short on time, prioritize your remaining work, placing "functional application" at the top, and things like "tip strips on subVI controls" at the bottom.
I hope these tips prove useful, and if you're taking the CLD soon, good luck!

Monday, January 19, 2009

My Weekly Nuggets are Back!

I decided to start writing weekly nuggets again. Check out the first 2009 nugget here. Enjoy!

Edit: A little background on my weekly nuggets. Back in January 2006 I decided to start posting a LabVIEW tip or trick every week on the NI Discussion Forums...this was the first installment. I kept it up for about a year, then announced my retirement, since it was getting pretty hard to come up with a new tip every week for 52 straight weeks. Anyway, after I found out that people were bummed that my nuggets stopped, I started posting "occasional" nuggets...much less frequently than weekly. Now that it's 2009, I decided that, to celebrate my 10-year anniversary at NI, I'd start posting weekly nuggets again. Let's see how long I can keep it going!

Tuesday, January 13, 2009

LabVIEW Certification: Preparing for the CLAD

The road to LabVIEW Certification starts with the Certified LabVIEW Associate Developer (CLAD) exam. According to the CLAD webpage, the purpose of this exam is to demonstrate that the test taker has "basic proficiency" using LabVIEW. Since I've been writing LabVIEW code as my full-time job for over seven years now, I figured my work experience sufficiently prepared me for the CLAD. I recommend taking the sample exams available at the CLAD webpage above to make sure you are familiar with what kinds of questions to expect on the exam.

For me, the actual CLAD ended up being very similar to the practice exams, and I finished it very quickly (I think I was done with the 40 questions in about 15 minutes). If you have been writing LabVIEW code for several years, I doubt you'll need to do much preparation for this one. If you think you'll need more prep, I recommend watching the CLAD webcast and carefully studying the preparation materials. Both the webcast and the prep materials are available at the CLAD webpage linked above.

Additionally, there have been several threads on both the NI Forums and the LAVA Forums over the years that discuss the CLAD. Some threads have more general discussions, while others are specific to questions on the sample exams. Searching these forums for the term "CLAD" should get you to most of these threads.

Friday, January 9, 2009

"Artisan" Sounds a Lot Like "Architect"

I just found out today that I passed the CLA exam! Ever since I found out after NI Week 2008 that NI employees could receive NI Certification, I signed up in a hurry...first for the CLAD, then the CLD, then the CLA.

Look for some posts in the coming weeks about how I prepared for each exam.

Don't Like It When Quick Drop is "Populating...Please Wait"?

I wrote an occasional nugget a few months ago with some advanced Quick Drop tips. Apparently word hasn't gotten around yet, because people still sometimes ask me if there's any way to avoid the initial "Populating...Please Wait" message the very first time Quick Drop is used after starting LabVIEW.

So to reiterate, if you go to Tools > Options > Controls/Functions Palettes and choose Load palettes during launch, your LabVIEW launch time will increase by a few seconds, but Quick Drop will be immediately ready the first time you use it.

Spread the word!