Understanding the Invoke Node

In the past, to create some organization, I would create some VIs and then call them from other VIs just by running it as a sub VI where I might pass it a value and the Sub-VI might return a value. Pretty basic stuff and honestly, pretty useful.
However, now I have discovered the subpanel and would like to use it in conunction with other VIs. To my understanding, in order to run and pass data to and from the VI being run in the subpanel, I need to use the invoke node. I'm a little unsure on how to use them though. It's not real clear on how I can pass data to and from the subpaneled VI.
Any help on suggestions or explinations would be great. Thank you.
Solved!
Go to Solution.

I would be repeating what crossrulz said...
However, I suspect you were trying to say "Property Node" and maybe using a reference...
A large influence will be how you are calling the sub-vi in the subpanel. Can you show us part of that code?
EDIT: I just saw you reply..
You can use the "Find Examples..." inside the help menu. There must be 10,000 examples of Queues & Notifers in this forum. A simple search should provide lots of hits. These are easy to implement. Much easier than it appears..
To learn more about LabVIEW, I suggest you try looking at some of these tutorials.

Similar Messages

Using the invoke node VI Strings.Import

I'm achieving a program to translate the captions which are on the front panels of existing programs.
I use the invoke node VI String.Export to create a file containing the differents properties of the front panel objects of the target VI.
I modify the fields <CONTROL ID .... name="xxxxx"> to change the captions and then i use the invoke node VI Strings.import to uptade the target VI.
Then i use the invoke node VI Save.Instrument to save the modifications.
The problem is that the Log File created by the invoke node VI Strings.import indicates me :
Parsing error while importing strings
to traduction_1.0.vi
from C:\Documents and Settings\Administrator\Desktop\work\Labview\Exos\traduction\Vi_import.victl
Tue, May 16, 2006 9:43:20 AM
Error occurred while parsing for String object. Control name does not match.
Which means that it can't change the captions name.
Do i badly use the invoke nodes ? Do i have to use an other function?

Apparently you are changing the control label, not the caption. If you created a caption for the control, the caption value should appear in the <PARTS> body, nested into the <CONTROL ...> tag.
You can't change control labels this way. Labels are used to identify the control to which you are applying changes. Changing the label would cause the control not being found.
Paolo
Paolo
LV 7.0, 7.1, 8.0.1, 2011

How can i save the output array of the invoke node "commands values" into a specific file

I must save the setup of vi commands'. I use an invoke node called "command value" wich give me an array with the name of the specific command and his value. How can i save this array into a specific file to load it later if o need. Must i change the array format?
Thank you

Hi,
I have attached two VIs.
The first one "Ecriture fichier tableau" (writer) permits to collect all control's values in an array (dbl) and to save it as .bin file. You had to convert variant type into dbl type. (You can do the same with string type if you wish. You will save datas as .txt file for example)
The second VI "Lecture tableau fichier" (reader) permits to retrieve all the datas you saved in the file.
I think this responds to your question.
Regards,
Attachments:
Control values.zip ‏26 KB

I am using the NI application note "Calling IVI-COM drivers from LabVIEW" I created an Automation Open and an Invoke Node, after wiring

the 2, the AN asked to right click the Invoke Node(this is step9) and choose initialize. However there is no intialize option on the pop up menu. Anything am I doing wrong? I am using Labview6 and I did add the "enableCustomInterface=True" in the INI-fileThank you for your help.
T Tall

the 2, the AN asked to right click the Invoke Node(this is step9) and choose initialize. However there is no intialize option on the pop up menu. Anything am I doing wrong? I am using Labview6 and I did add the "enableCustomInterface=True" in the INI-fileT Tall,
What's the number of the application note "Calling IVI-COM drivers from LabVIEW"? I'm unable to find what you're looking at.
Thanks,
--Bankim

How to get a LabVIEW class object to expose an invoke-node method?

Hi,
      I like the property/invoke-node "paradigm" used for interacting with "objects". Can LabVIEW-class objects expose their properties and methods this way? Can one or more LabVIEW-class objects be compiled into a library or "assembly" (or other distrubution format) that allows the property/invoke-node usage?
I've looked at (but not completely understood) "Creating LabVIEW Classes". Have also searched for related posts.
The pic below shows an invoke node wired to a class with a Public VI "VAT.Status.Hello.vi". I'd like to see VAT.Status.Hello show-up as a Method. (I just tried "Select Method", and selected "VAT.Status.Hello.vi" but dialog's "OK" button stays greyed-out.)
Cheers.
Message Edited by tbd on 03-29-2007 03:15 PM
"Inside every large program is a small program struggling to get out." (attributed to Tony Hoare)
Attachments:
VATStat.JPG ‏54 KB

Hi Aristos,
      Thanks for the reply!  It was a bit dissappointing, though.
It appears the LabVIEW-class object will be moving away from (what seems to me) a convenient object-interface presented by the invoke-node/method paradigm - which allows us to interface with a large set of "objects" (.NET, ActiveX, LabVIEW GUI, VISA Resource, ?) in a similar manner and independent of the object's origin. Being able to read the methods and parameters that appear in these nodes is also helpful for understanding diagram logic!
I do like the option of dropping a friendly "VI looking" icon on the diagram, but perhaps an optional - even default - VI-icon representation for a class-object invoke-node is feasible - so the LabVIEW class-object could be the more generic object first, but with a traditional-G representation(?)
Given the answer "We would like, someday, to support the property node"
and "in the next version of LV, wiring the LV class to the property/invoke nodes will break the wire so we'll avoid confusion in the future",
... I guess you'll break the wire in the next version, but (perhaps) allow it again - if support of the property node is ever implemented?
Regards.
P.S. For the record, huge THANKS to whoever it was that straightened-out enumerated-types (somewhere) between LV4.1 and LV6.1.  Every time I add or remove an enumeration in a typedef, I silently give thanks to the bright and thoughtful soul(s) who made this valuable tool work so well!
Hello. This is your friendly neighborhood R&D guy for LabVIEW classes.
Regarding your request about property and invoke nodes as relates to LV classes....
Short story: We would like, someday, to support the property node. We have no intention of ever supporting the invoke node.
Long story: As we were creating LV classes, we had to evaluate the right programming interface for these things. We wanted LV classes to behave as new data types in LV. A developer should be able to create a LV class, then give it to someone who doesn't even know OO programming, and that second programmer could use the new data type without learning a lot of new concepts. From this principle, we held fast to the idea that the programming interface should be subVI calls whereever possible. The invoke node is really nothing more than a VI minus the icon. If you want, you can popup on any subvi node and uncheck the option "View as Icon". This will make the node display in a way that has the terminals listed as text, like the invoke node. So, at the end of the day, the invoke node is simply a subroutine call in LV that is language dependent, as opposed to the language independent iconography of LV generally.
The property node is a slightly different story -- the functionality of a property node is actually different than an invoke node as its terminals are various subsets of the properties available, not a fixed list of parameters like the invoke node. The property node provides a nice interface for setting multiple properties in a block and only having to check a single error return. Very friendly. Our intent is to allow you to create a VI that has 5 terminals: object in, object out, error in, error out, and either a single input or a single output of your chosen type. VIs with this conpane could be marked as "properties" of the class and would show up when you wire the class wire to the property node. We would call the subVIs behind the scenes as needed to get/set the properties.
This is on the longer term roadmap because it is "syntactic sugar" -- it sweetens the programming style, but it is not necessary to program effectively. You can get the same effect by writing those same VIs and stringing them along on a block diagram "railroad track" style. We'll probably get around to it in three or four versions of LV -- there are some major user requests that impact functionality that have to get done first.
PS -- in the next version of LV, wiring the LV class to the property/invoke nodes will break the wire so we'll avoid confusion in the future of people thinking there's a way to use these nodes.
Message Edited by Aristos Queue on 04-02-2007 09:56 AM
Message Edited by tbd on 04-03-2007 12:39 PM
"Inside every large program is a small program struggling to get out." (attributed to Tony Hoare)

Error when executing VI with "Invoke Node" in loop

Hello,
please check if this is possible what i am doing here or if there is a better way to do it.
The goal is to have a VI that i can start in TestStand which is then running in a loop until i set a global variable.
I do this currently with:
1.) Starting the VI with "Invoke Node" (see screenshot 01)
2.) This Vi is then running all the time in a loop until the global for exiting is True (screenshot 02)
3.) Then i have another VO to set the Quit-variable to true
Normally this works as it should, but sometimes i get the error-message:
Invoke Node in NameOfTheViCalledInTestStand.vi
Method Name: Run VI
VI Path: NameOfTheViThatContainsTheInvokeNode.vi
LabVIEW: Das VI befindet sich in einem für diese Operation unzulässigen Zustand.
The question is: what does this error mean and what better ways are there to do what i want to.
Perhaps for better understanding, the VI which runs in a loop executes dll-functions to enable and disable an ample-tower to make a light blinking.
And because there is no function "blink", i have to make it on off on off on off....
So the vi loops and makes on off until i say "quit" then blinking stops.
Thanks for any ideas
Attachments:
01_InvokeNode.jpg ‏8 KB
02_ViRunsInLoop.jpg ‏23 KB

I cant´t do this "Try changing the "Run" node
to "Wait Until Done" = True." because then the TestStand-Step is
hanging until the loop is finished.
I only want to start the "blinking" and the continue normally in the sequence.
To
avoid that the vi with the "Invoke Node" is started twice a have a vi
above it whick checks with the globalVariable "IsCurrentlyBlinking" if
the start is allowed.
If IsCurrentlyBlinking= True then nothing happens.
So normally it can´t happen that it starts twice. Only if the GlobalVariables are not correct.
The
variable "IsCurrentlyBlinking"is set to TRUE in the subvi before the
loop starts and after the loop is finished its set to FALSE in the
subvi.
Attachments:
03_CheckStart.jpg ‏16 KB

Excel ActiveX invoke nodes are broken

I am using LabVIEW 2007. We are using a VI that runs on most of the PC's in our facility however on some the "invoke node" related to Excel functions don't operate. They are broken and the VIs won't run. We get errors that the "Invoke Node: contains unwired ro bad terminals". When going to select methods or properties not all of the properties are shown as seen on the functional PCs. Some of the properties are missing from the selection menus, thus making it incompatible.
Has anyone seen this problem and a solution?
Thanks
Manliff,

What about separating the compiled code from the source? I recognize that this will only work in LV2010, but I expect that that will prevent the compiler from breaking activeX code that depends on a different version than the local one...
Testing this idea is on my to-do-list, but I was wondering if anyone has tried it already.
-Barrett
CLD

Why do I get an error 1000 when using vi server with invoke nodes?

I use the invoke nodes with set control value and run vi. I want to use the called vi on the same machine and in parallel and I do not want to wait until it is done. If I set wait until done to true it works, if I set it to false I get the error message. Why is that and how can I solve that problem??

Hi,
Using LabVIEW 7 I was able to do what you want. I modified an existing example. The main vi will load the a second VI, and then the main VI will do "set control value" on a numberic labeled "Numeric" and you'll be able to see that it is changing the control value.
I've attached the modified VI.
Attachments:
parallel.zip ‏148 KB

Invoke node error in PDSF vi

Iam using NI datalogger,for reading analog and digital inputs.In this datalogger there are many sub VIs.when i run the data logger iam getting the errors like, the sub vi PDSF_logistics.vi(process data standard format )is not executable.The error what it is showing is
Invoke node:Invalid method
The method selected in the invoke node is invalid or no method has been selected. Right-click the invoke node and select a method.
Invoke node:Invalid refnum class
The refnum class that is being passed into this node is not fully defined. This is because the refnum is defined using external files, and one or more of these files are missing.
Iam attaching the VI please have a look in to it.
Attachments:
PDSF_Logistics1.vi ‏75 KB

Hello dilreddy2001in:
It seems that the activex reference is not attached to an activex class.
In the front panel:
1] Right-click "refnum"
2] Go to "Select ActiveX Class"
3] Click "Browse"
If you copy/pasted it from another VI, you might as well do the same in order to determine the ActiveX Class.
I hope that this helps.
Good Luck...
PS
You also forget to attach 'PDSF_ErrorText.vi'

Does "Run VI" invoke node work on strict references to REENTRANT VIs?

I am using LV 6.02 on Windows 2000.
I am trying to use the "Run VI" invoke node method with a reference to a Reentrant VI, with no success. (It works when VI is not reentrant. Perhaps there is a reason this cannot work. But if not, I wonder if there is a workaround, or if LabVIEW 6.1 has a fix?
Hopefully the picture of the block diagram I included is sufficient...but I also included the actual code just in case.
Thanks!
Steve
Attachments:
block_diagram.jpg ‏66 KB
Parent_VI_Example.vi ‏43 KB
Prototype_subVI_shell_for_Simplex_Fit.vi ‏40 KB

Hi, Labviewguru,
Thanks for taking the time to look at my admittedly messy (flawed) block diagram. I will try to state my ultimate goal:
You may be familiar with Levinberg-Marquardt nonlinear curve fit in Labview, which is about 5 VIs in a LLB file. In order to change the type of curve fitting, one has to either modify a formula node in the lowest subVI (Target Func and Deriv), or place a different subVI in there. That's fine until I want to have many different sorts of algorithms.
What I was thinking of doing is instead passing Target Func and Deriv a reference to the VI which would perform the calculations. This would allow me to use the same fitting code to fit different types of data with substantially different methods--without modifyin
g the low-level fitting code at all.
I'm not sure this is going to make any sense to you, but thanks again for your help.
In regards to your answer above, let me clarify somewhat. I had the call by reference node in there to prove that the reference to the VI was "good" and worked fine...this same reference was passed to the invoke node, which didn't have any apparent effect.
Also, I don't think the path to the VI I am opening the reference to is redundant. It is required to tell the "Open VI reference" which VI to load.
I agree that using references to pass values around is not generally a good idea: I was using that method for my supposed versatility in the future.
Thanks,
Steve

Error 15 at "Run VI" Invoke Node When Building a LabVIEW Executable

I am trying to run a vi by using the "run VI" method of the invoke node. The source code works perfect. However, I cannot run the vi when I use the executable version. Specifically, I get the Error code 15 at the "error out" output of the invoke node while using the executable version. Why is this occuring?
Thanks

Hello ameng,
This behavior is typically the result of trying to call VI that has had its front panel removed. The KnowledgeBase linked below has more information on this issue.
Error 1 or 15 Opening Dynamic VI from LabVIEW Application
Please let me know if you have any other questions about this issue.
Regards,
Matt F
Keep up to date on the latest PXI news at twitter.com/pxi

How to get the parent node of the current node?

Hi all,
i want to get the parent node of the current node and the not the parent of the parent node.
thank you very much

Hi,
the parent node of <subnode1-2>29.99</subnode1-2> is (node1), how can do to get <node1> throw <subnode1-2>29.99</subnode1-2> the sub node of <node1>.
As per my understanding the parent node of <subnode1-2>29.99</subnode1-2> is book not the node1.
If you want node 1 as a parent of subnode1-2 than your xml will look like this.
<?xml version="1.0" encoding="ISO-8859-1"?>
<bookstore>
<book>
<fathernode>Harry Potter</fathernode>
<node1>
       <subnode1>29.99</subnode1>
       <subnode2>29.99</subnode2>
</node1>
<node2>
       <subnode1>19.99</subnode1>
       <subnode2>19.99</subnode2>
</node2>
</book>
</bookstore>
and also if you want tom retrive float data than refer following XPATH.
"//book[[price='1000']]/price/text()"
Regards,
Manoj Bilthare

Method Not Found Invoke Node error 1316 using Solid Works IEdm

Hi Forum members,
I have been having a problem with calling a function in a dll file. I have attached the VI as example. When I use the GetFile method I get a reference to that. I then use the Invoke node and recieve a list of methods, the first of which is ChangeState. I select this method and wire all required inputs and when I run the program I receive the error at that invoke node that the method does not exist. How is this possible? I have tried various methods to ensure the inputs are all correct and none have worked. I do not believe the fault lies in the inputs, but I cannot for the life of me find the problem... Perhaps someone has experience using Solid Works in Labview? Any help would be appreciated.!!
Cheers
Ben
Attachments:
SetFileSatus.vi ‏18 KB

I have determined that there is a problem with the Invoke node not recognising the function. This is a Labview problem as the function is listed and selectable, so when the error comes saying the function is not found, this is a problem with Labview and not the dll. The Function when selected also has the right input parameters that automatically appear. How is it then that the method is not found when the program is run?

Using invoke nodes to change a control on a server vi

I am trying to pass a parameter to a vi running in parallel with my main vi. I am using invoke nodes to do this without any problems. In server.vi I want to respond to a change in the control using an event structure. I have found that when passing the value to the vi using the invoke node from client.vi the event structure does not respond to the change in value. Is this correct behaviour? In the attachment run client and server, any change in the client panel is reflected in server without a response from the event structure. Running server by itself a change in the cluster causes the event structure to respond as expected. Thanks in advance for any help on this.
Attachments:
Test Invoke Node.llb ‏47 KB

The set control value method is the same as using a local variable or the value property - it doesn't fire the event. To fire the event, you need to use the Value(signaling) property. To do this, you need to get a reference to the control. You can do this by taking the Front Panel property of the server VI and wiring that reference into another property node. Then, you get an array of references to all the controls on the FP. You will need to find your control and wire its reference into the signaling property and then the event will fire. There are, of course, other ways of doing this - this one is fairly complicated, since you have to find the reference.
Try to take over the world!

Error 1039 invoke node

Hello,
I have been using the Invoke Node with RunVI method. The code was working for years. Now I get error 1039 which says the VI has been aborted. This is disturbing as nothing has changed with my code.
TommyHelter

Tommy,
Something obviously changed. Have you installed any new software recently? Moved this VI from one pc to another? Disconnected hardware?
Most likely the VI you are trying to run is popping an error and aborting because of it.. Try manually opening the targeted VI and running it. Do you get any errors? Does it run successfully?
Rob K
Measurements Mechanical Engineer (C-Series, USB X-Series)
National Instruments
CompactRIO Developers Guide
CompactRIO Out of the Box Video

Understanding the Invoke Node

Similar Messages

Maybe you are looking for