Error, in Getting started with Labview. Chapter 3, part 4.

[LandyRover]

Hi.

Still struggling on, trying to find the time to work through the "Getting Started with LabVIEW" document.

Only 19 days left to go, and I'm still only in chapter 3!...

Right.  In the "Saving Data When Prompted by a User" exersise, part 4...

4.   Right-click the Signals input of the Write To Measurement File
      Express VI and select Insert Input/Output from the shortcut menu to
      insert the Comment input.

Problem is, that option is greyed out, so not available!...

I did what the instructions said, I right clicked on the "Signals" input, and it doesnt do what it says on the tin!

Any pointers?   Please don't mention search the help, I've crashed the entire LV environment 3 times now, trying to search for something in there.  It's OK if it finds someting, but it seems to bomb at times, when there is some ambiguity when searching.

Also, I won't be able to do anyting with any replies for a day or two, as I have to go up country to a customer, and mess about with hot oil, high volts, and lots of RF.  It never ends.   (I've still got the day job to do, while trying to fight my way through this "evaluation".   30 days of "Use" would be better, than 30 calendar days for some of us.)

Regards.

Dave Baxter.

Technical Manager: AR-UK Ltd.

AR United Kingdom

[elset191]

I believe it is greyed out because all of the input/outputs are already shown, so there are no more to insert. 

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LandyRover wrote:

Any pointers?   Please don't mention search the help, I've crashed the entire LV environment 3 times now, trying to search for something in there.  It's OK if it finds someting, but it seems to bomb at times, when there is some ambiguity when searching.

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For future reference, all of the LabVIEW help is online too.  see here

[Dennis_Knutson]

It's greyed out because you already have all of the possible inputs and outputs. Don't you see the input called 'Comments'?

[Rod42]

To get to the situation you're in, you probably either did lots of the add input/output, or more likely you picked up a resize spot at the top or bottom of the express vi and dragged it. You can reverse that by going to the resize spot at the bottom middle of the whole thing (watch the cursor change to an two way arrow, pointing up and down) and dragging upwards.

Look closely at the express vi when you resize it. What you're doing is moving I/O terminals between the body of the VI and the lines underneath it. If you have terminals showing to the left or right within the blue bit of the express VI (at the moment you won't) hover the mouse over them. If you have auto-tool on (it will be by default) the cursor changes to the wiring tool and the terminal name appears in a tip strip.

Rod.

[Pattos]

Hi LandyRover,

I think the Insert Input/Output is greyed out because you did not click the right spot.

It seems to me that you clicked the Express VI itself right in the middle.

But as you stated, you have to "Right-click the Signals input".

So you have to click the little arrow on the left side of Signals.

Hope I did not tell you something you already knew.

Regards,

[LandyRover]

Nope..

I put the mouse cursor over the "Signals" input legend, and right clicked, *Exactly* as the document tells me to.

If (and I agree) the comments legend is showing already when you go and plant that tool on the block diagram, then either the Getting Started guide needs altering to reflect the new reality, or the default visible items selection in that tool needs altering to agree with the Getting Started document.

I've been arround PC's long enough to know the difference between what to click (or right click on.)  But when not only me, but a collegue too, also gets the same issue, it must be real.

It's entirely repeatable, so go download the LV2009 package, install the f9 patch, and try for yourselves.   Of course, knowing your way arround the system, it'll take you less than 30minutes to get that far down the document.   Not the nigh on 10 days it's taken me so far.   Not all due to LV it has to be said, but a proportion of it is, due to researching our way out of ambiguity and confusion.

If you make it work, I want to know how.

Again, I've been involved with PC's and other similar stuff for decades now, it's just LV I'm new to.   Little errors in documentation, can seem trivial, even irelivant, for those who know the system already, but are often confusing total show-stoppers for new users, who don't know their way arround.

In my industry, little errors like that, can create huge costs when you applying inapropriate stimulus to something, and blow it up by, because you followed bad (or just plain confusing) instructions.

Dave.

PS: And why does this editor, when you backspace to erase the first chr of a word you got wrong, also erase the immediately prior space too, when you type the correct chr?

[Dennis_Knutson]

When I place a new Write to Measurement File on the block diagram (2009/f9), it looks like this  and the procedure in the document works exactly as written. I suspect that you may have changed some default behavior accidently (by modifying something on the Options screen) if you do not see the above.

[Rod42]

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LandyRover wrote:

Nope..

I put the mouse cursor over the "Signals" input legend, and right clicked, *Exactly* as the document tells me to.

If (and I agree) the comments legend is showing already ......

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On my system it ISN'T already showing. We're talking about something being done between dropping the express VI and you clicking on the signals line. If you have already dragged a resize handle to it's fullest extent the picture you show is what we would expect. Try droppping the express VI again, taking great care that if you move it from the dropped position you DON'T pick up a resize handle. That's the blob at the top and the bottom of the express VI. If you want to move it click within the blue area, keeping away from the edges. Clicking on the pencil and paper icon is just fine. That will (should) avoid any more pitfalls.

Rod.

[LandyRover]

Hi Dennis, and everyone else..

That is not how it looks when first dropped on the BD.  On my machine, it is partialy expanded by default, after you clear the Configure dialog that pops up ocupying most of the screen.

Again, if it makes a difference to the way the Right Click shortcut menu works, it should be documented in the Getting Started document, especialy as it seems to be a critical point.

OK, explain this...

I've just rubbed out the save to file VI, cleaned up the broken wires etc, and then planted a new one on the BD.   Once I cleared the Configure dialog that covers up most of the screen before you see it the first time, the VI was partialy expanded.  I forget the exact list, but "Signals" was not at the top.

I did *EXACTLY* the same again, deleted it, cleaned up, and then planted a fresh new one.   That DID appear that time with nothing but the "Signals" item showing, and two down caretts below that, indicating more items.

So......

Why the different behaviour each time, on the same BD, in the same session.   Some underlying working data not being correctly initialised when invoked?  Of course, that never happens, right? ('C' programmes eh?)

Trying some more, it seems the behaviour loosley depends on just how close to the edge of the While loop grey border you place it.   Odd.   I have a 1280x800 screen to play with, and a 1280x1024 second screen I use for the Getting Started document.  That is the absolute maximum I can have, due to hardware limits.

I also find, that if you fully expand the "Write to Measurement File" VI block, then fully collapse it, then expand it again, all the items in that list have changed places!  Why?

I had noticed earlier that there is no uniformity in the layout of even the items common to many if not all VI blocks (error in, and error out to name but two) Sometimes one is above the other, sometimes the other way round, sometimes they are not even ajacent to each other.   Has that been done as a source of minor ammusement or something?

Talking to another colegue here, who just wandered in to see how I was getting on with this.  Seems he also has tried the introductory entry into LV (V8.something) in the past.  But he too, found too many things that behaved differently from one time to another, so abandoned it as a lost cause, then decided to learn how to use Visual Basic with NI-GPIB IO instead.   Not without issues either he said, but at least it all behaves exactly the same, each and every time.

End of the day now...

Regards.

Dave B.

[RavensFan]

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LandyRover wrote:

Why the different behaviour each time, on the same BD, in the same session.  

.... 

I had noticed earlier that there is no uniformity in the layout of even the items common to many if not all VI blocks (error in, and error out to name but two) Sometimes one is above the other, sometimes the other way round, sometimes they are not even ajacent to each other.   Has that been done as a source of minor ammusement or something?

Talking to another colegue here, who just wandered in to see how I was getting on with this.  Seems he also has tried the introductory entry into LV (V8.something) in the past.  But he too, found too many things that behaved differently from one time to another, so abandoned it as a lost cause, then decided to learn how to use Visual Basic with NI-GPIB IO instead.   Not without issues either he said, but at least it all behaves exactly the same, each and every time.

End of the day now...

Regards.

Dave B.

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It's because it is an Express VI, those magical blue boxes that do hundreds of things behind the scenes so you don't have to.  There is a lot more programming going on there, probably with hundreds of rules in its code it follows to try to simplify the creation of VI for someone who doesn't know LabVIEW.  Do one thing just a bit differently, probably in ways you don't even notice, and how it goes through its code to generate the blue VI will vary and give you a different result.  Where sometimes the Error In line is shown, sometimes above, sometimes below.....   If you don't the what is on a given white line, you can click on that item and select among the other inputs or outputs to be shown.

Deciding to abandon LabVIEW because something like an Express VI looks one way one time, and slightly differently another, is a pretty poor excuse.

Ultimately, you really want to get away from Express VI's.  There great for getting some code up and running quickly, great for newbies, and they can be configured to do a variety of things, but in the end, you'll find you want to do something more advanced than what the Express VI can handle.  At that time, you'll start doing some real programming with LabVIEW with the real functions.