how many ways can I update a control programmatically???

[richjoh]

1. local (or global) variables

2. property nodes.

3.

I'd like to know if there are more possibilities especially when a control is used. we can always right a value into an indicator when an indicator is used.

[RavensFan]

---

richjoh wrote:

1. local (or global) variables

2. property nodes.

3.

I'd like to know if there are more possibilities especially when a control is used. we can always right write a value into an indicator when an indicator is used.

---

I would say that is it.  But you could do it with either local variables, or property nodes that are directly linked to the control.  Or you can pass a reference to a control into a property node.

And you can write to the value property, or the Value(signalling) property.  The Value(Signalling) is advantageous when you want to have event structures trigger off your programmatic change.

I crossed out globals.  Although they are a way to pass values around a VI or to other VI's, they aren't directly tied to a control.  You would still have to use one of these methods to get the value out of the global and into the control.

Message Edited by Ravens Fan on 04-10-2008 10:11 AM

[Ben]

And to add one more convoluted method (just for achedemic purposes)

4) If the cotrol is bound to a DataSocket then write to the associated URL will work.

5) Invoke node Set Control Value

Ben

[richjoh]

OK, I have comments on two different CLD exams I've taken, the partial paste follows.

Case1: "property nodes are used to update values"

Case2:"Use of local or global variables"

So, there where no globals used. For case1, I did use a few property nodes and a few locals. For case 2, I used 1 local variable for each control or bundle (no duplicates) for updating inside the state machine.

So I'm trying to make sense of the comments here. What's the criteria for updating a control programmatically? Since we can't use constants to write directly in a control (like an indicator) I'm scratching my head.

[TWGomez]

There is also data binding.

[smercurio_fc]

That's a totally different question. The initial question were the various methods. The question "What's the criteria for updating a control programmatically?" is vague. The answer is: it depends on what you're doing. For instance, I can think of one reason right off the top of my noggin for updating a control programmatically: setting initial values when a program starts up, like loading in the values used the last time the program was run.


Message Edited by smercurio_fc on 04-10-2008 09:38 AM

[richjoh]

OK when you update a control what method is used for the NI Certification team to issue points? Local variables or property nodes... (we have all posted the pro cons of using either on here no need to repeat that again). Ok yea, SV too.

When your program starts up what used to update your control typically? We all have our own "Style". I've yet to determine what NI requirement is on this during the CLD.

[Ben]

"...what method is used for the NI Certification team to issue points?"

Nobody but the graders can answer that Q and they will not.

THe only help I can offer is to study the course material required for the level of certification you are afte as if it was gospel.

For the test, forget about any advanced discusions you may have read on the forums, they will only get you in trouble.

Re: that particular Q, we had a active discusion of the sample test ..... I beleive it is due to be re-written.

Ben

[richjoh]

Ok, so the CLD could be a moving target. I posted these question in an email and now awaiting an answer.

What are the criteria used to grade the CLD exam? What are the specific finding and recommendations used when determining a grade?

In two instances of taking the CLD the graders comments are shown below.

After a comparison of the two cases, here are my comments. “Property nodes and local variable are not to be used”. I’ve posted a question asking what other ways are there to programmatically update a control. “Unnecessary bends in wires are not to be used”. What criteria determine when a wire bend is unnecessary? Should all wires not have bends thus bends in wires are not allowed? “Errors not handled….error terminal on property node not wired”.  As I read the exam requirements, I did not come across a case to handle an error in any step. Simply connecting an error terminal and providing a case doesn’t handle errors. I’m almost certain my code in Case2 does not generate programmatic errors. “NOT gate used rather than inverted input where available”. Are you saying NOT gates are not be used, is there some advantage? Maybe I was able reuse duplicate code in Case2 and in one of the cases the NOT gate was appropriate since is read well on a block diagram and the change was effortless.

--------------------------------------------------------------

Case1:

Style: Overly complex solution. Property Nodes used to update values. Unnecessary bends in wires. Error terminals on property nodes unwired. Errors not handled.

Functionality: Application not fully implemented. Logic of implementation is not correct. Boolean latch action is not implemented where necessary.

Documentation:

Case2:

Style: VI is not modular – repeated code is not placed in SubVIs. Use of local or global variables. Unnecessary bends in wires. NOT gate used rather then inverted input where available. Errors not handled.

Functionality: Application does not function as specified.

I have no idea what NI is looking for as far as “Style”. Lets define this and have a point system in place for determining “Style”. What “Style” allocates 15 points in the CLD exam?

[Ben]

Use the VI Analyzer to comment on your style. If you make the VIA happy you should be well on your way. There is the LV Style guid included with LV for more details.

Ben

"Hater of Tests"