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

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How to set the value in the xml node.

Hi
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<employee>.
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Hi Dhiyane,
You will have to set the contains property if the id node to "metaData", that is;
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How to get dynamic paramete value in the context node?

Hi, experts,
There are some attributes in the node context(ee_node) that contained the attribute named "ANSSA" in the view(test_view) in the WDA for abap. In the method WDDOMODIFYVIEW of the view(test_view), there is dynamically string , ex."ANSSA". How can I get the value of the "ANSSA" from the node(ee_node)?
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Method wddomodifyview.
*importing   para    type   string.
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You can reply back to me via e-mail if you think we should discuss this internally at [email protected] or [email protected]
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Hello Neha,
Thank you for your help in advance.
I am very sorry that the above method name ought to be "modifyview", not "wddomodifyview"(I write the error word in the question so that I am very sorry.). I am very sorry the error method name occuring your misunderstand.
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I don't write such code in the method modifyview: lv_anssa like ls_ee_node-anssa. Because I am not sure that the "para" represent the name of "ANSSA", and the "para" may represent other attribute in the node context, ex. "ENDDA"(date type) attribute. The "para" is only the transfered parameter from other method for representing the name of attribute.
Method modifyview.
*importing para type string.
DATA:
lo_nd_ee_node type ref to if_wd_context_node,
lo_el_ee_node type ref to if_wd_context_element,
ls_ee_node type wd_this->element_ee_node.
I cann't write such code. Because I am not sure that the para represent the name of "ANSSA"******************
data lv_anssa like ls_ee_node-anssa.
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lo_el_ee_node = lo_nd_ee_node->get_element( ).
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I don't know how to replace the "???". Do you give me more hints?
Thanks a million.
Regards,
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Action Script to add a parent node value to the top node

I need to add a new parent node value to a hierarchy for the top node. The action script parameters to add a node is "Add|Version|Hierarchy|Node|Parent Node|Leaf property". I am at a loss on what to do for the top node since there is no Parent Node above this top level, but the parameters require it. I have reviewed both the user manual and admin manual, but did not find any assistance. Can anybody help me?
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You have the answer with you, don't get confused between Parent Node and Top Node in this context, while Adding a new node your Top Node will become your Parent Node.
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If you still have confusion, simply do the below,
1. Right Click on your Top Node and Add a new Leaf or Limb Node manually
2. Once added, go back to Home -> Script
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Hi
i imported a WSDL into my WDJ application.
where on context mapping, i mapped the MODEL with my CONTROLLER.
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Context
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----------ModelNode2
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similaraly can anyone tell me how to set the SKIP for other 2 attributes......
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Hi Chintan
Thanks for your response....
fine ... i understood your solution....
but , my problem goes and makes me dizzzy
i have 10 mandatory filed in my Webservice..
i passed all the 10 mandatoy fileds and get perfect Response In WEBSERVICE Navigator....
i tried passing the same value via WDJ application as show below
since i have a node element with cardinalith 0..n
I set the value those i passed in Webservice Navigator.....
wdContext.nodeRequest_getSubmitRequest().
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But Here ,I get a Error Message Saying :Error in Submiting Request : No role seleced for the request.
so , i even checked whether the node is populated with rite value by printing them after executing the WSDL.
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Output
After Push_execute_WSDL
COntroller getRoleId -- BASIC
COntroller getSysId -- R3
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The MOST wired thing is
if i didnt set and Role , SysId in webservice navigator , then Error thrown at Webservice Navigator is
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on following same thing , if i didnt set Role and SysID in WebDynpro then, i get error as
Error in Submiting Request : No role seleced for the request.
How is this possible....
any help on this would be appreciated...
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Help comparing the value of a button using the Property Node (I get a variant)

Dear Sirs:
(I'm using LabView 6. I guess the solution is different for 6.1)
Currently I have created an array of Boolean RefNums (which point to many, many buttons). When I need to know when any (and which) of the buttons was pressed I just compare every element on the array with the constant TRUE. It fact, as the array is built from RefNums, I should compare the VALUE from the Property Node.
The problem here is that the Property Node for this type of Boolean is a LV Variant, and I need to compare this with a TRUE/FALSE value.
I tried to convert the TRUE constant to a LV variant and visc. But nothing works... I always get that none of the buttons was pressed.
Here it co
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I have enclosed a VI that contains what I've achieved until now, which is nothing
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Attachments:
Other_Main_Menu.vi ‏103 KB

Javier,
There is another problem in your code: the booleans are not polled by the main loop so they will remain false until the user presses them again. This renders the boolean latch action useless.
What you can do is to change the mechanical action of the booleans to non-latch. When you detect a "true" in the polling loop, set the boolean to false again. One added benefit is that once all boolean are non-latch, the value property won't be a variant but a boolean so conversion is no longer needed.
LabVIEW, C'est LabVIEW

Htree-Value of the parent's selected node

Hi all!
I have an htree in oracle forms10g and I would like to have the value of the parent selected node. There is a function to trap the value of the selected node but I also need the parent's value too.
My tree is structured like this
company--> department--> service-->service_status.
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I would like to have all the records where service_status is equal to "active"
for the service located above the "active" selectedI'm not sure what you mean by that, but try "ftree.get_tree_node_parent(my_tree, my_node);" for getting the parent.

SubVi with feedback nodes used more than once inside a While Loop

All,
I have a subvi that does a set of operations and uses 3 feedback nodes. I am using this subvi inside a While Loop a total of 4 times. I've noticed that all instances used share the same result at each corresponding feedback node but I would like to have an individual result from each of them. Is there an easy way to go around this problem? I have come up with ways to avoid this: a) create a different vi for each time the subvi was used. b) use global variables instead of feedback nodes. Is there any easier way to go around this issue?
ExamplePlease note that both subvi's are the same) If on my first subvi I calculate a maximum value and get 1.29 (then goes to feedback node) on my second subvi i get 1.01 my feedback node at the second subvi still registers the maximum value to be 1.29. (and I want it to be 1.01!)
Hope this is not too confusing, I've been scratching my head with this for a while, can't find the "easy" button. Thanks in advance.
-Pop
Im using 9.0.
Solved!
Go to Solution.

Attaching the code would be helpful. Anyway, I am not sure how multiple feedback nodes are supposed to operate so I will defer that to others to answer. As far as being able to use distinct values or instances if you are using a subVI you could mark it as reentrant. That way each call to it will behave as it it were a copy of the VI and it will have its own memory space. This should include the feedback node. You may be ending up with a single subVI and in reality a single feedback node. If you need to pass data between calls than simply wire the data through. You could also use an Action Engine to store and retrieve values. An AE is a MUCH better solution than a global variable.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

Clearing of Feedback Node

Greetings,
Is it possible for the Feedback Node to be cleared from our VI?
So that the feedback node will not use the previous value for the next execution.
My project is dealing with optics and motorized stages.
After running it once, for about 1 degree, when we change the movement to 5 degrees,
the programme will run 1 degree, then 5 degrees.
Apparently, this is not what we desired.
So please do assist me.
Your help is much appreciated.

Hi,
Could you post the ocde you've already done?
Do you know which behavior you expected?
The behavior you're explaining seems to rely on commands you've done. Where is the problem?
Olivier L. | Certified LabVIEW Developer

Feedback Node Initializer Being Ignored ?

Hi
I have a feedback node sat in a For Loop, the number of iterations is determined by an input array. The same input array is wired to the initializer terminal of the Feedback node. The Feedback node delay is set to 3 and yet the output of the node only contains the first value of the array for the first 3 iterations. It's easier to show than describe.
So I would expect the output Array to contain the values 3,1,0,0,1,2 yet it actually contains 3,3,3,0,1,2
If I wire the scalar value 99 to the initializer then I get the expected 99,99,99,0,1,2
What am I missing ?
This is LabVIEW 2011 for MAC OS X
Don't forget to give Kudo's for a good answer !
LabVIEW Champion
Certified LabVIEW Architect
Certified TestStand Architect
Solved!
Go to Solution.
Attachments:
Feedback Node.vi ‏8 KB

To expand on Swatts answer a bit more. You are actually only initializing the feedback node with a single element because you have the array auto-indexing at the loop tunnel.
If you fed the entire array into the For Loop and the initializer terminal, it would have worked the way you expected.
Attachments:
Feedback%20Node[1].png ‏6 KB

Feedback Node Bug?

I came across an odd situation when using a Feedback Node where a established a delay of more than 1 iteration. (LV2011)
I have a waveform datatype. I wanted to delay the waveform by an iteration of the loop before displaying in a graph, so I added a feedback node.
Then I realized I wanted to delay it by a few more iterations, so I went into the properties and set the delay to be greater than 1.
Because I had stale data in the feedback node after 1 run, I wanted to intialize the feedback node, so I right clicked on the initializer terminal and picked create constant. An array of waveforms was created, and this broke the output of my feedback node since it was wired to a scalar waveform type.
If I do not have a delay longer than 1, (more normal feedback node), then a scalar waveform is created and no problems.
Interestingly, I tried the same thing with the more basic numeric datatype, an array was created in one case, a scalar in the other, but the array did not break the output of the feeback node. I'm not exactly sure what an array into the intializer would mean for a long delay feedback node. It might make sense that it allows you to create an array of different initial values for each step, and this link on the web help mentions that http://zone.ni.com/reference/en-XX/help/371361H-01/glang/feedback_node/. But the help embedded in LabVIEW doesn't mention that. (See attached image.)
See attached snippet.
Attachments:
Example_VI_BD.png ‏33 KB
Feedback Node Help.PNG ‏145 KB

Ravens Fan wrote:
The only other question I have is whether it is appropriate for an array of elements to be generated at the intializer rather than just an element. A 1 item delay feedback node generates an element, a 2 or more delay generates an array as default. What is the difference in the feedback node that treats the creation of that constant differently if Z=1 vs. Z = 2 or more. It is just a feedback node with a different delay. While an array would make sense as a data for the initializer for multi-delay feedback nodes, it is just as valid to have a single element as the input if you want the same output to repeat.
I say yes, it is appropriate to generate an array for a node with a delay > 1, especially given the connection to the unilateral Z transform. However, you are under no obligation to provide an initial value for all values, you can put a single value into the array and it is equivalent to the scalar input. You can even put two values in and the second will be repeated until the delay is reached. With the SR you have to initialize all or none.
Not everyone has my handy-dandy QD shortcut to convert scalars to arrays (why not?), but I still think it is easier to either live with single element arrays or rip the constant out of the array and rewire than it would be to create a scalar and then reach for the array container or build array.
My 2c, I rarely increase the delay personally, but I do not do FPGA either.

CRS Install hostname being used by more than once for the same node.

Hi, we're installing The Oracle Clusterware and on the Cluster Configuration screen of the universal Installer (the one were you specify the clustername and clusternodes) we get the following error message in a dialog box when the next button is clicked:
"You must enter unique values for the public node name, the private node name and the virtual hostname for all nodes in the cluster. The name, node1, that you entered is being used by more than once for the same node."
Has anyone experienced this error message before and know what the cause is?
Could it be a problem with the /etc/hosts file?
Thanks in advance,
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Make sure you allocate separate IP addresses on your network for the VIP addresses on each RAC node (this is not the same as the machine IP already configured on the OS).
Also, the installer may complain if your private and public IPs are configured under the same subnet.
Finally, as mentioned before, check that name resolution for all the IPs to be used. On all RAC nodes, your /etc/hosts file should be configured with:
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- private name and IP addresses of ALL nodes
- VIP name and IP addresses of ALL nodes
Hope that helps
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Feedback nodes in Error cluster

Some time back I
had posted a VI called Simple StateMachine template. Based on the
comments from fellow members I have redone it and am attaching it
herewith. ( LV7.1 + Win_XP Professional )
If you just open it and check the block diagram, you will notice that
LV has introduced a feedback node in the error cluster looping between
DAQMx function Write Digital Output and Read Analog input. I am not
sure why LV does this even though the two functions have no common
reference or relevance between them.
You can also try this : Just remove the data lines to the two Digital
Out functions, and also the error cluster with Feedback node . Rewire
the Error cluster but this time without the feedback node. And now if
you try to connect the Digital Out data lines, you will find that the
Data lines are drawn with feed back nodes !!
I am sure LV is trying to tell me something - only that I don't understand what it is. Can some one elaborate on this ?
Thanks
Raghunathan
Message Edited by Raghunathan on 07-04-2005 08:29 PM
Raghunathan
LV2012 to Automate Hydraulic Test rigs.
Attachments:
PRP_Main.vi ‏288 KB

You have an impossible loop in your code (Run it with execution highlighting to verify):
Dig8-15 relies on data from the case structure.
analog input 0-7 provides data into the big case structure
This means that Dig8-15 cannot execute until the case has executed, but the case must wait for data from analog out. LabVIEW is smart enough to insert a feeback node such that AI0-7 gets the error from the previous interation. This is NOT a desirable situration.
Without the feedback node, yuor code is broken. AI0-7 cannnot run because it must wait for DO8-15 to execute. DO8-15 cannot execute because it must wait for AI0-7.
You should:
Uncheck the diagram option "Auto insert feedback nodes in cycles" to make sure to get broken wires so it is easier to find the problem.
FIx your dataflow. Please make sure your wires flow left-to-right, it make errors like this less likely. You need to wire the error clusters in the order the subVIS execute.
I hope this is clear enough, but please ask is you continue to have problems. Good luck!
Message Edited by altenbach on 07-04-2005 07:18 PM
LabVIEW Champion . Do more with less code and in less time .

Feedback node crashing bug

I have came across a nasty bug that caused Labview 2010 SP1 (Runnnig Win 7 Ultimate x64 bit) to crash without any warning.
To replicate the bug do the following:
Add a numeric control and another indicator to the front panel
Switch to block diagram and add a feed back node
Connect the initializer terminal of the feed back node to the output of the control
Now do ANY of the following to cause the bug:
Press the run buttong (which is broken due to not connecting the input of the feed back node) it will turn to a normal run without displaying the error
Do an extra action and undo it, the run button will turn from list error normal
So far the Vi can be saved normally. Now connect the output of the feed back node to the indicator and try any of the followings:
Save the VI
Close the VI
Create a new project and select to add the VI to the project
This will cause Labview to crash without any notice!
When you are at step 4, the bug is there but harmless. Once you combine it with step 5 (connect to indicator), the bug is active and cause crashing. I have attached a snapshot of how the Front panel/block diagram look like before saving (since it can't be saved). Notice how the run button is enabled although the input of the feedback node is not connected.
I have tried to replicate the error on Labview 2009 but couldn't.
Attachments:
FBN Bug.jpg ‏56 KB

Dear ªL¡
Thank you for briging our attention to this issue.
I replicated it on LabVIEW 2010 SP1 and confirmed, that in LabVIEW 2011 it has been fixed.
Thanks again!
Best regards,
Mateusz Stokłosa
Applications Engineer
National Instruments

Feedback node behavior

I never expected a difference between Array1 and Array2 in the attached vi.
In the feed back version, if the incoming array is all false, Feedback indicator is not initialized to empty, and Array2 contains stale data.
Attachments:
FeedBackNode.vi ‏23 KB

beavercreek wrote:
Dang it, sorry about the attached. I was trying to be nice by back versioning the source code, but I went beyond the feedback node feature.
I don't really have a question, I just expected the initializer to intialize Feedback (and Array2) to empty, regardless of if the true case ever executed.
My bad, and a heads up to others.
I don't know why you'd expect an initializer to initialize something back to empty after code has executed. The initializer only operates on the feedback terminal when it executes. Once you get into your For Loop, the initializer terminal never comes into play again.
One problem with your code is that your terminal is at the output of the feedback node rather than the output of the build array. So the data going into the feedback array indicator is always from the last iteration where the boolean was true, not the current iteration.
If you want to get the data in the array indicator after the for loop is done, then I would use the variation with the shift register, and not use the feedback node. Or if you use the feedback node, use the initializer terminal on it, then it isn't necessary to have the case structure and you can wire the data directly out to an indicator outside the for loop.
Attachments:
FeedBackNode[1]_BD.png ‏32 KB

Flushing values in the feedback node

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