Feedback node from case structure

checkLED.vi is my first rev of this. Then I realized I can incorporate the 345/348 selection into the case structure, which resulted in checkLED2.vi. However as soon as I did this, the feedback loop inserted itself. I don't understand why this happened and what it means. The string coming from the case structure is an INPUT to the two 34970 vis. There is no feedback going on here. If Labview sees this as feedback, why didn't it insert the feedback node in checkLED.vi?
Attachments:
checkLEDs.vi ‏23 KB
checkLEDs2.vi ‏23 KB

Look at the dataflow you have created by moving the strings into the case statement. The case statement requires data from the iteration terminal and from the VI in the sequence structure. The sequence structure requires data from the switch VI which in turn requires data from the case statement. This is a clear feedback situation that you did not have before.

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How extract data from case structure

Hi all, I would like to extract the data from case structure, it's circled in red in the attached file. How should I do it? Thanks for taking your time to look at my post. Your help is greatly appreciated.
Attachments:
bp.jpg ‏161 KB

Thank you guys for your prompt reply.
As u can see from the vi, there's an error, I need the values in the circled area to be passed on to the block ( Bundled by name)
Thanks !
Attachments:
fyp_bp_only.vi ‏90 KB
fyp_bp_only.vi ‏90 KB

Is there a known issue with emailing from case structures

Hi,
I am working on a quality control vi for data coming in as a text string. I need to be able to have the vi perform a check with the responce to the check (true or false) will cause different steps to then be performed. I was able to get the vi to perform 1 check and email out if the responce was false. When I tried to add a second check if the responce was true, the vi would run without any errors but would not email out or would only email out from the first check even if the first check passed and it was the second check that failed. This was all done without case structures. I then started using case structures with the true responce leading to other checks but the false responce leading to an email generation. For some reason even a simple one check with the email generation happening in the false case will not work. There are no errors or anything, it goes through the whole process correctly but will not send an email. Please help!!
Tim Koles

Hi,
Here is the vi and the sample text file it calls for. You will of course have to change the path name. Feel free to call me if you have any other questions. Thanks
Tim
410-326-7259
Attachments:
SPLIT_WEATHER15.TXT ‏130 KB
Weather QCexample.vi ‏63 KB

Converting from case structure to arrays

I am working on a set up that write out 8 digit binary to a connector block. I had it set up with a case structure but there are over 40 different writes and it is becoming way too convoluted. I know it would be much easier to do this with arrays but I have no idea how to use them, please help.
Here is my current program:
Attachments:
42sampleWorkingCode.vi ‏974 KB

Here is a quick attempt to do everything with arrays. See if it makes sense to you. As you can see, the code is much simpler. (LabVIEW 8.0).
You should be able to adapt some of the ideas. Many additional simplifications are possible, for example you could calculate the port 0 values directly from the outputs of the upper Q&R function. Try it!
LabVIEW Champion . Do more with less code and in less time .
Attachments:
timedBackboneWithLEDnewlogoMOD.vi ‏384 KB

Property node for case structure

Is there any way to programatically pull out the list of cases (strings) from a case structure at run time?

Thank you tbob and tst. I do use the enum "trick" in other places (I once saw it used in an example somewhere) and I am nervous about the Selector Strings property available through scripting after reading about it on the LAVA forums site (I am a novice LabView user and I mostly didn't know what they were talking about).
I have a VI that processes "tags" embedded in various text fields that many of my collegues use. As an example we have a custom front end to the LabView simple error handler that processes our custom error codes and handles timed popups, writing to the device error log, etc. The default behavior can be modified by inserting tags (<popup 60> for a dialog box with a 60 second timeout or <no device log> to supress writing an entry to our device error log) into the "source" string of a standard error cluster -- just like the <append> tag used by the Simple Error Handler.
In most instances there are only a few tags so I just use a case structure in the "tag processing VI" to select the desired action indicated by each tag. When people are parsing their strings for tags, they like to have a qick and easy way to test if a string is a vaild tag. I provide a separate "validator VI" to do this. I frequently add and remove tags from the case structure as things evolve, but I often forget to update the list of valid tags used by the validator VI or some one runs into an older version on another machine. I wanted to have the vaildator VI access the case structure on the tag processing VI to get the current list of vaild tags.

Merging Signals From Case Structure

Hello,
I am making a scanning program which requires several cases to be evaluated within two for loops. I've hooked up both conditions in a while loop, and I know that because of the conditions only one of the wires will be executed. In two of them I modify a parameter and one I leave it alone, but I am unsure of how to connect the three to the module on the right. Any tips?
Thanks for your help,
gordonj005
Solved!
Go to Solution.

When you drop a new case structure onto the block diagram, LabVIEW creates a structure with two cases by default.
To add additional cases, right-click on the case structure and select "Add case". You can either "Add case after" or "Add case before".
You can learn a lot by experimenting, right-clicking on things and examining your options, and using the LabVIEW help. Since it seems that you're pretty new at this (not knowing how to create additional cases was the clue-in), I'm trying to give you some tools for learning on your own. I'm not trying to be mean.

Start event from case structure

I'm running my main programm inside an event of an eventstructure.
Beside this main event I additionally have 3 other events in this event structure.
To save "screen space" I would like to start indirectly one of my other events from a case
placed inside another event.
Is this possible - would be glad if you have an example.

You are still completely misunderstanding the purpose of the event structure (see also my answer the other thread).
The main code of the program does NOT belong inside an event structure. What good is an event structure if it is tied up indefinitely inside one of the event cases???
An event structure is most useful for dealing with interactions by the user and must be ready to handle those at any time. It is not a tool to "save screen space" (whatever that means). If you are running out of diagram space, consider wrapping your code segments into subVIs.
LabVIEW Champion . Do more with less code and in less time .

Flushing values in the feedback node

I am using a feedback node to build an array.
When I stop the VI and run it once again, the values in the feedback node from previous iteration are introduced in the array.
How do stop this from happening ? Is there command /VI which could be used to remove the values in the feedback node?

Right-click on the diamond looking box on the left side of your for loop, and select Create --> Constant. This will create an empty array constant. If the code you posted sits inside another loop (e.g. a while loop), then right-click on the initializer terminal again and select Move Initializer One Loop Out to get to your outermost loop. This will initialize the feedback node only when you start the program.
To reinitialize all values to default, you can do something like this:
Edit: Re-posted code as VI
Message Edited by Sima on 11-20-2008 09:54 AM
Attachments:
reinit.vi ‏16 KB

Programatically get the states of case structure

Dear all,
Is there a way we can programatically get all the states of a case structure in my VI.
I know that there is no property node for case structure, but I am sure there must be some way that labview ppl must have thought about it.
Awaiting....
cheers
Sree
Solved!
Go to Solution.

With scripting, there is a property node for the case structure and you can query the names of the cases. You will need LabVIEW 8.6 or greater for scripting. Get started here. Note that scripting is unsupported, except through the scripting message board.
This account is no longer active. Contact ShadesOfGray for current posts and information.

Editor bug if you drag a case structure over an index/replace elements node on a in place structure

To reproduce:
Drag a case structure over a index/replace array node
You'll end up with this train wreck. Autocleanup no longer works
Interestingly, you can still get it to compile but setting the boolean to true doesn't run the true case. Warning: dragging the below snippet onto your block diagram will probably crash LabVIEW
Select all that and drag it into a new VI. Run autocleanup and the development environment will crash: Exception: Noncontinuable exception (0xC0000025) at EIP=0x00000000
Running LabVIEW 2014 SP1 with nothing special.

To quote Obi-Wan
This is not the bug you are looking for..........
Now search for "Clear as mud"
Having a Wired treminal inside an IPE driving conditional code should break the snot out of that code and cause the compiler to puke all over! The lack of check for that insanity is causing the crash! Don't do it! Just think of how you are abusing the poor IPE. What if you had a breakpoint on the Inplace Boundary and changed the boolean? That would necessatate a copy inside an inplace structure....... NO!!!!
Or, more to the point as best I understand: (Add duct tape adound head as needed)
An IPE must exist in one "Clump" Terminal Reads exisist in their own "Clump" (although you can read many terminals in one clump) So you require a clump to read the boolean terminal inside another clump. Clumps cannot reside in clumps since clumps are clumps that stand apart from each other by definition. The run arrow should be broken but is not- hence LabVIEW crashes. Makes sence to me except the clumping algorythm didn't catch the insanity and the run arrow wasn't broken. so the next edit caused all hell to break loose.
(If I missed domething here I am going to learn something today)
Jeff

Cases programmatically from xml in case structure

I want the cases in my case structure to be updated programmatically from an xml file. Is this possible?

You can, but don't forget what Felix wrote - a VI can't programmatically change itself. You'll need a separate VI to modify the Case Structure you're working with.
This example gets a reference to the target VI, traverses for all Case Structures, selects the target by its label, adds a frame and gives it a Selector Label. You'll need to modify the last three VI Server nodes to accommodate your particular application.
Good luck.
<edit> take a look at my CaseSelect JKI RCF Plugin, it contains a bunch of Case Structure manipulation code.</edit>
Jim
You're entirely bonkers. But I'll tell you a secret. All the best people are. ~ Alice
Attachments:
contains case structure.vi ‏9 KB
controls case structure.vi ‏12 KB

Can I use a formula node to start the execution of a case structure?

Hi,
I am working on editing a VI to make it much easier to understand (for colleagues and non LV users). For one reason or another, the VI's creators did not fully make use of the power of case structures and other structure types. In the application we need it for, the instrument cycles and repeats measurements on several objects. We are interested in measuring the motor currents for several motors in the system. As it stands now, for each sample object's run, there is a separate sub-vi diagram which displays its waveform trace and several indicators such as max current, time at max, etc. That code was contained within a T/F case structure and copied and pasted 20 plus times.... Obviously the vi became extrememly cluttered and needed a huge screen to see. The trigger for the current case structures is an EQUALS comparison between one input (which is the sample object counter; and this part I will likely leave unchanged since it makes a lot of sense already) and a constant which was defined 1 through 20+ for case.
I have since made one case structure and 20+ instances of that case and have labeled them (at the top selection box near the detent arrows) "1", "2", 3, etc. I am wondering if I can use a formula node to act as the "trigger" which sets each case structure running? I believe that a simple IF statement should work. Please see a snippet of my attempt at making this in C below.
For the node, I defined X as the input and Y as the output. The input to the node, X, is connected to the sample object counter. The output, Y, is connected to the case selector of the case structure. My attempt at the code is below:
int32 y
For(x == 1)
y = "1";
For(x == 2)
y = "2";
etc, etc.
Is that above code snippet correct? Do i need something like "ENDIF" or "end if" at the end? Does "y" have to be defined as "int32" or can it be something else?
Thanks for the help!

Is your formula node doing anything else besides what is shown?
Why don't you just wire the value that is going into it at X directly into the selector of the case structure?
Attachments:
Example_VI_BD.png ‏2 KB

How do i output multiple arrays from a case structure to create one larger array

I currently have a vi that has one hardware input that i needed to take a measurement then be moved and take a similar measurement at a different point. To accomplish this i used a while loop inside a case structure. The while loop takes the measurement and finds the numbers i need while the case structure is changed per the new measurement location. I want to take the data points i have created in each case and output them into a single table. I assumed to do this the best way would be to get the data from each case into its own built array and build a larger array but I cant get the information out of the case structure so that it all inputs at different places.
thanks for your help
Attachments:
Array.vi ‏30 KB

Hi Ross,
attached you will find a solution for your table building problem.
I would suggest thinking about program design - having the same case content in several cases doesn't make sense. I also would not want my user to press several stop buttons depending on choosen measurement...
Best regards,
GerdW
CLAD, using 2009SP1 + LV2011SP1 + LV2014SP1 on WinXP+Win7+cRIO
Kudos are welcome
Attachments:
Array.vi ‏45 KB

In the attached VI I dont understand why data from the inner case structures are not being transmitted to the array.

In the attached VI I don't understand why data from the inner case structures are not being transmitted to the array.
Thank you.
Solved!
Go to Solution.
Attachments:
TEMP.vi ‏25 KB

It took me some time to figure what you are trying to do but I think I have it now.
The SR is still required.
What is happening is your "Bundle By Name" is replacing all of the fields of the cluster, not just the value coming out of the case structure. So to maintain the cluster stuff you do in earlier iterations you can either...
1) Put the "Index array, Bundle by name, and Replace array" inside the case structure and ONLY bundle the value you are setting in that iteration. (as you will see Tim post shortly)
OR
2) Move the Index array before the Case, unbundle all of the fields and feed teh case structure and run them across the case so that ALL of your output tunnels come from the coresponding input tunnel EXCEPT for the filed you are trying to set.
Ben
Message Edited by Ben on 05-05-2010 01:31 PM
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

3750x Stack UTIL-3-TREE: Data structure error--attempt to remove an unthreaded node from a tree

A Cisco Stack 3750X switch report the following error message:
%UTIL-3-TREE: Data structure error--attempt to remove an unthreaded node from a tree.
every minute +-20 sec
Cisco IOS Software, C3750E Software (C3750E-IPBASEK9-M), Version 15.0(2)SE4, RELEASE SOFTWARE (fc1)
analog bug: https://tools.cisco.com/bugsearch/bug/CSCsz93221

WS-C3750G-24PS-E C3750-IPBASEK9-M version 12.2(53)SE2
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%UTIL-3-TREE: Data structure error--attempt to remove an unthreaded node from a tree
Port then fails authentication and goes into vl-err-dis

Feedback node from case structure

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