what VIs do not have block diagram?

[ACarpio]

Hi, I'm studying for CLAD and theres a question in the CLAD Topics details about what VI do not have block diagram?. I read in help that polymorphic VIs don´t have Diagram Block or Front Panel ( Labview help / Creating Sub_VIs). However, I can see that if I make double click in  a polymorphic VI, for example,  Read Key.vi or DAQmx Timing.vi they have front panel, moreover, they have a diagram block, so I am missing about that......

    I know too that VI express do no have diagram block or front panel, the have a configure window. If I select open the front panel option,  the VI express changes to Sub-VI and I have access to front panel or block diagram. So I think VIs express are those VIs that do not have diagram block. Am I right?

 Anyway, there a doc or paper that give me information about this topic?

Thanks for the anwsers....

[tst · Accepted solution]

Polymorphic VIs are a single VI which call a collection of other VIs. The called VIs have a BD, but the polymorphic VI itself does not.

Global variable VIs don't have a BD.

Express VIs have dynamically generated code which calls a subVI which does all the work. I don't think it's created as a VI you can actually use until you choose to open its FP, but I'm not sure about the details.

Controls don't have a BD.

VIs with the diagram removed don't have a BD.

There may be some others, but I can't think of any at the moment. Overall, I can't say I really see the value in this question.

[ACarpio]

Hmmm, Controls are terminals, they are not VIs..... and the relevance of the question, well maybe you make this question to CLAD test maker.....

anyway thanks for your answer

[tst]

Custom controls are VIs.

If you want to see a list of options, try clicking File>>New. At least some of those are VIs.

[ACarpio]

Sorry Man, but custom controls are not VIs, in fact their ext are .ctl, not ,vi. See labview help, fundamentals.

[pacific]

Technically, you can have two types of custom controls.

(1) Custom control, typedef and strict typedef - These are pure controls that do not provide the ability to add custom behavior. No block diagram.

(2) XControls - XControls are custom controls to which the user can add custom behavior along with appearance. These have a block diagram.

As far as the question for the CLAD goes, I think custom controls will fall in the category of controls and not VIs. XControls are a more advanced concept.

[parthabe]

What are the choices given for the answer?

Can you post that document/link here?

[tst]

The fact that controls have the .ctl extension does not mean that they are not a VI. You could rename a .ctl file to have a .vi or .caribbean extension and it would still work the same.

LabVIEW considers them to be VIs and displays then in the All VIs in Memory property and other places.

Incidentally, looking at the help for the VI Type property shows the following:

---

Indicates the type of VI. Invalid VI type, Standard VI, Control VI, Global VI, Polymorphic VI, Configuration VI, SubSystem, Facade VI, Method VI.

LabVIEW returns the invalid VI type value for invalid VI references.

LabVIEW returns the SubSystem value for subVIs for the LabVIEW Control Design and Simulation Module that you can place only on a simulation diagram.

The Configuration VI type is not supported.

---

The last two are both used for XControls and both have diagrams.

[ACarpio]

Dear TST,

          I was reading deeply the help labview with the information that you wrote and other source as The G programming Manual and another sections of Labview help. You are right, in the VI type Property  include the global variable VI and Control VI, I can not say it is wrong, but if We read the basic definition, for example of global VI, you can check that when we create a global variable, Labview automatically creates a "special global VI", which has a front panel but no block diagram. As you well know the basic definition of a VI, it is not agree with this, the same is for control VI. I think that the definition of VI has been abused and many concept are named with the word VI. You can check in the menu File/ New (you talked about that) to create a new VI only we have option to Blank VI (standard VI), polymorphic VI and templates. However, Global Variables,  Control Custom, XControl are in the section of "other files" and the description don't defined as VI, as defined as other "objects" of labview.

   So as I said before, I think the word VI  has been used in many concepts and brings misunderstanding! But I said again you are right. Why all this issue, beside to study to CLAD Exam, sometime We make program and use concepts as a robot....! and We do not think a little more about "why. 

sorry my bad English.....

The Caribbean