Table Reference Global Variable

Hi,
Inorder to update a table in One VI from another VI, i need a Global Variable Reference of that Particular Table. How shall i create it.
Anybody please comment on this.
regards,
mfp.

You can use LV2G,
an example is attached, you may work on same lines.
I am not allergic to Kudos, in fact I love Kudos.
Make your LabVIEW experience more CONVENIENT.
Attachments:
Another VI.vi ‏16 KB
LV2G.vi ‏11 KB
Table owning VI.vi ‏13 KB

Similar Messages

How to print global variable in smart form table cell

hi,
i have smartform and i insert table in it, i also have set global variable, i want to show variable in table cell.
regards
shahid rais

Hi Shahid Rais
You can use this global variable that has been declared in anywhere as you like.
For displaying global variable in table lines, You can first set the column and row of the table by using the table tab in table node . Then, u can decide either the variable u want to used will be placed on header, main, or footer. After that, right click on one of the table part, and choose create table line. After choosing the correct line type as already been declared in the table painter, just simply right click on the table cell, and then create text node.
You can now enter your variable by using "insert field".
And don't forget the & & signs before and after your variable name.
Regards,
William Prawira

How do I store VI References in global variables and access them later

From what I know, Labview automatically deletes VI references when they go out of use. Is there a way for me to override this so that I can access a set of preloaded references in a separate VI? Essentially I would like to open the VI's dynamically into the memory, store the references in global variables and access them at a later time. The VI's I'm referencing won't be known until runtime. I know its not the safest way to do it, but it would be the most productive on my end.
Thank you
Clay Upton

I'm not sure what you mean by "a later time", but a VI reference will remain valid as long as the VI is in memory. If you don't unload the VIs, the references will remain valid.
If you do need to unload the VIs, for whatever reason, I would suggest the following:
Create a functional global as your interface for obtaining the references.
Feed the paths to the VIs into the VI when initializing it (since you don't know which VIs in advance).
When calling the VI to obtain the references, have the VI check them first (using the Not a Number... primitive). If it sees that they're invalid, it can open a new reference and return that.
You should note that when a VI is removed from memory, the data space is used is released, so if those VIs are expected to hold data (using shift registers, etc.) this will be a problem.
The description I've given will only be usable in certain instances (and it has its intricacies), but you didn't really give any details about what you're actually trying to accomplish.
Try to take over the world!

How do you reference a created global variable in a report text field?

I have created a parameter using the Globaldim statement in a script file. when I reference this parameter in any other script file during the current DIAdem session the value is passed without any issue. Call the variable parmxyz where I assign it a value of 25.3
The help section under Globaldim mentions that global variables can be referenced in all panels, scripts, and dialogue boxes. When I try to insert a text box on a report page using the @@parmxyz@@ it returns NOVALUE where I expect to see 25.3 (for example).
When I substitute @@CurrDate@@ I do get the date, so I know the text box is valid. What am I doing wrong?
Steve M

Hello Steve!
It should work the way you did it. But their are some circumstances wich might prevent it:
You have reseted the global script engine. All variables will be lost.
You have a Sub with the same name in a command extension script. There is no warning ;-)
One Test you can make is to put in '@@TypeName(paramxy)@@' as the expression to see the variable type. You can also try a realy unique variable name. The last option is to use ItemInfoGet to get detailed infos about your variable.
Matthias
Matthias Alleweldt
Project Engineer / Projektingenieur
Twigeater?

Dynamic call of a vi with a reference stored in a global variable

Hello,
I am trying to program a VI which calls DAQmx functions in some cases, in other cases DAQmx may not even be installed. To prevent a broken arrow on machines where DAQmx is not installed, I want to use a sub-VI containing the DAQmx function calls which is called dynamically by a main VI. For speed I want to prevent continuous opening and closing the VI reference, so I want to store the reference to the sub VI in a global variable. In this variable I also want to store the Analog Input Task. I want to use an initialization VI to write the VI reference of the sub VI and to configure and start the Analog Input Task and write the Task ID to that Global, too. In that way I was hoping to be able to improve the performance of the dynamic calls and the Task calls. BUT - when I write the refererence and task to the Global and read it out from another VI, the reference is not valid anymore and the Analog Input task is also not valid, even if both the initialization VI and the Global are still open (but not running). Does somebody have an idea how to solve that? It is a bit difficult to describe, so here is what I want to do in a shorter description :
- run a initialization VI which
defines a reference to a sub VI which will be called dynamically later on
and a AI task ID definining a DAQmx physical channel configuration to use for subsequent read cycles
and writes both (VI reference and AI task) to a global variable
- run another VI which
reads the VI reference of the VI to call dynamically from that global
runs the corresponding VI dynamically
the dynamically called VI performs an AI task corresponding to the DAQmx task ID read from that global (it reads an analog value for instance from the
physical channel configured by that AI task)
Why all that? To prevent creating and destroying the VI reference for each call of the sub VI for speed. And to use the configured DAQmx channel for subsequent read tasks only if the subVI is called dynamically - if it is not, then the application will not see the DAQmx calls and therefore no broken arrow will occur if no DAQmx is installed on the machine.
Can somebody help me with this? Why can't I store and read out the reference to the sub VI to/from a global, and why is the AI task not valid when read out from the dynamically called sub VI? I am somewhat lost with all that...
Thanks in advance,
Gabs

Uh - I am almost getting crazy with that
Kevin, that solution is the right one for programming an application. In that case everything will work fine. But during testing, it is more convenient to call all VIs from their front panels one after another. That's how I'm doing it for everything that needs to be exchanged between such VIs: store them either in a global or in a functional global variable. In that way the user can "play around" with the VIs without wiring them together in a main VI. Therefore, after some thinking I liked Davids idea with that daemon VI (I solved that by adding a boolean in the initialization VI to choose if that daemon is necessary - during testing phase - or not - when using the VIs in a main application). BUT:
David: It does not work!!! I have exactly done what you proposed and this daemon VI is really running, having a True/False frame with a constant of False wired to the selector and holding both the functional global and the dynamically to call VI in the True frame. In that way, after initialization is finished, both VIs are still running but idle. Anyway, when I read back the value of the reference or the DAQmx task, it is invalid again!
That really costs just too much time. Does anybody have any idea what to do now? David, I was hoping that your suggestion would solve the problem, because it would be logical that it would - why then is LabVIEW destroying the reference and task anyway even if that daemon VI containing the functional global is still running???
Regards,
Gabs

Global variable in a Table

Hi!
Can i use any column in a table as a global variable? Is it at all possible in Any version of Oracle? I know that if we use package - we can create a global a variable there. If u had any knowledge pls reply.
Satyaki.

Hi Satyaki,
Try to understand the difference between a variable and coumn of the table.
What exactly you need a global variable for the application or own Datatype for a table?
If you requirement is variable then use Package without body or type object. But if your requirement is your own datatype use TYPE in the table.
Thanx.. Ratan

How can I obtain a reference to a global variable?

I wish to change the contents of the columns in a global multicolumn listbox. As far as I can see, the only way to access the columns in a multicolumn listbox is to create a reference to it and access the ItemNames property. But how can I create a reference to a to a global variable?

You can open a reference to a global as if it is a normal VI and then get a reference to a control on that VI. I have included a little VI here with a test global variable to get the item names from an MCL in that global. I needed the MCL in the main program just to force the reference to a strict MCL reference. You could turn this into a sub VI that just returns the item names of a named MCL if that works better (then the MCL that's only used for reference would not be on your main front panel).
This VI searches through all the names of the controls on the referenced VI until it finds the one that's asked for.
Have fun with it.
Rob
Attachments:
Get_Ref_to_MCL_in_Global.zip ‏158 KB

What is the difference between using a global variable,passing a valuee and using a reference?

I have created a project that consists of several VIs. Only the main VI has a front panel and the others perform functions. The function VIs are dependent on controls on the main VI's front panel. I have several ways of passing the value of the controls. One is to use a global variable and just place it on the dependent VIs. Another option is to strictly connect the terminal from the control to a VI connector block and pass the value directly. My last option is to create a reference of the control and reference it inside the dependent VIs, but this would also require connections to be made to the VI block.
What are the advantages/disadvantages of these options?
-Stephen

5thGen wrote:
I have created a project that consists of several VIs. Only the main VI has a front panel and the others perform functions. The function VIs are dependent on controls on the main VI's front panel. I have several ways of passing the value of the controls.
1) One is to use a global variable and just place it on the dependent VIs.
2) Another option is to strictly connect the terminal from the control to a VI connector block and pass the value directly.
3) My last option is to create a reference of the control and reference it inside the dependent VIs, but this would also require connections to be made to the VI block.
What are the advantages/disadvantages of these options?
-Stephen
1) Globals are evil and introduce race conditions.
2) The sub-VI only get the value when it was called and updates that occur while the sub-VI is runing are not sensed by the sub-VI
3) This uses property node "value" or "value signaling" both of which run the user interface thread which is single-threaded and you incur a thread swap hit to performance. You also have a potential for race conditions.
The are various methods for sharing dat to/from sub-VI which include Queues and Action Engines.
I hope that hleps,
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Global variable (internal table)

Hello Experts,
how can I create a global variable (internal table) so that I can fill in inside WDDOINIT and later within another
method inside the view.
Thx in advance
Best Reagards
ertas ilhan

Hi,
Go to attribute tab and declare Your variable there.
You can access that variable in the following way in another method as well.
to use that variable use following syntax.
wd_this->variable_name
If you will declare the variable in component controller and define as public.
then you can access this in all the views of component.
to access that use following syntax.
wd_comp_controller->variable name.
I hope it helps.
Regards,
Rohit
Edited by: Rohit Makkar on Apr 28, 2009 7:53 PM

Control references vs. global variables

I guess my question centers on the appropriate application of control references.
I am writing a complex program that has a state machine at the top level, and, for one frame of the state machine, a while loop containing a couple subVIs, each of which contains many subVIs. The lower-level subVIs are affected by buttons on the top-level VI. Information from the lower-level VIs must be shown on the top-level front panel within the loop. My question is: what is the best way to do this?
(I have a previous version of the program that I wrote that keeps just about everything on the top level so that I can update the front panel, but this is not at all modular.
In addition, I considered breaking things up into more than on
e front panel, but this doesn't seem to be a good option for this section of this program.)
Last week I read about control references, and decided that this could be the way to deal with this issue. I have not worked with them before, so I want to know: Are control references an appropriate solution for this issue? Is it good programming practice to use them, especially to update data on charts and graphs? How do they compare programming-wise and efficiency-wise to global variables?
Global variables are another solution, I think, but I would have way too many variables to update. I think the advantage with global variables is that one could just insert a global variable in a subVI and not have to wire it up through the different subVI levels, which one would have to do (I think) with control references.
Can you offer any advice?
Thanks!

Paul,
The actual implementation of the solution is up to you. This is indeed a complex question.
I would offer the following advice:
On globals:
Try to avoid them. I try to restrict the use of globals to unidirectional. If you have ever dealt with a race condition, you will know why. Mistakes are often made with globals, and they are quite apt to become the biggest source of bugs in a program, especially in one as large and/or complex as your appears to be. If you must use globals, try using a shift register, or LabVIEW 2 style global instead. Basically, you use an unitialized shift register with two (or more) cases: Read and Write. This prevents race conditions, but only if the VI is non reentrant. However, implementation is still difficult.
Control References:
I also have read and heard about control references. I have had much use for them, for controlling the appearance of controls and indicators (and decoratiopns too, I guess...). However, I would caution you on using them to pass data around. This violates dataflow in a big way, as you are passing around pointers, instead of data. I believe this is difficult to implement, and even more difficult to keep straight. I personally recommend using them only for attributes of FP components, not for passing data.
So, what do I believe is the most elegant solution? I think a data server is your best bet. This is close to a LabVIEW 2 style global, but a little more active. Simply write all of your data into a subVI in any manner, a queue, a FIFO, LIFO, etc. Then, retrieve the data as desired. Buffering, queuing, etc are all handled by the data storage and retrieval subVI. It becomes sort of a small active database. The two sides (storage and retrieval) are independent of each other, and the code is all handled in the function. A basic version is a LIFO, Last In First Out, wherein the data is overwritten constantly. The data is then read by the reading VI, the front panel VI in your case, at any time, and the data is always the latest. You can add complexity as you need, such as making it a FIFO. This is done by simply writing the data to an array, then reading back the oldest value (by reversing the array and reading index 0.)
I believe this is an elegant solution to your problem. It does maintain dataflow, except that time is taken out of the equation, depending on how you look at it. It simplifies your program because you only need to do three things. Write the data handler, then drop in the function into the VI that writes, and the one that reads. It is also flexible in handling the data.
Good luck, and let us all know how you do.

Looking for something more robust than global variables

Hi,
The company I work for makes really big deals based on the Forms we develop,
and it makes me edgy to rely on :Global.variables to assign big amounts of money
to a field or another.
Maybe someone could direct me to a paper about a more robust scheme to run tests deciding what is going to happen next, like calling another form or populating another block?
Many thanks :-)
Message was edited by:
JeanParis

JeanParis,
I did a quick Google search, but didn't find any reference material on you question so I'll give you my personal preference. Bear in mind, it truly was a "quick" search. I'm sure there is information about this topic somewhere.
I use a Global Variable (GV) when a value is needed by significant number of Forms in the application. If the value of the is only needed by a few Forms, then I use a Parameter List. When I do use GVs, I only use them for as long as I need them. In other words, I'll assign the value of the GV to a Forms Block Item (base table or Control Block) or a parameter and then set the value of the GV to NULL. This ensures the value is only available "Globally" for as long as it is absolutely needed. This does cause a little extra work, but it make the Form safer in my opinion.
If I simply need to have access to a "Global Variable" within the scope of a single form, I prefer to use a Form Parameter (FP). I like using using FPs over a Control Block (CB) Item because there is less overhead (attributes of a FP) than with an Item (attributes of the Item) in a CB. I know this is nit-picking, but there is a cost associated with each attribute that is loaded into memory and I like to keep this cost to a minimum. (I suppose if you sub-classed your CB Item then it would share the attributes and reduce the overhead even more). I develop Forms for the web using Forms 10g so any time I can shave off the load-time of my Form is worth it to me.
Hope this helps.
Craig...
Message was edited by:
CraigB
Steve beat me to the punch. I like his option as well and have used this method a time or two. :-)

Dynamically create (global) variables

Hi,
Is it in anyway possible to dynamically create variables, like you can do in Forms:
DEFAULT_VALUE('test', v_test);
with v_test holding the variable, like 'GLOBAL.TEST'. Forms would then create me the variable as it doesn't exist yet, assigning the given value.
Like this I could read my variables' names from a DB table, dynamically create them, and assign their values. Inside the report I would then use them as lexical references.
I know I can create parameters inside the report achieving the same, but we need the table-approach for our translations. Getting rid of the parameters' overhead would be great!
Any suggestions appreciated,
K.

Where the lov is attached set the VALIDATE FROM LIST property to YES and craate one trigger for each field called WHEN-VALIDATE-ITEM and use the code as below...
IF GET_ITEM_PROPERTY('FORM_FIELD_NAME',ITEM_IS_VALID)='FALSE' THEN
:FORM_FIELD_NAME:=:GLOBAL.EmpCode;
END IF;
Don't forget to set NULL for global variable in KEY-LISTVAL trigger after assigning value to the form's field.
HTH.
-Ammad
Edited by: Ammad Ahmed on Nov 8, 2010 4:33 PM

Can F4IF_INT_TABLE_VALUE_REQUEST FM return a value in a global variable?

Hi everybody,
I need to use F4IF_INT_TABLE_VALUE_REQUEST FM because I have to let users select an specific option before choosing another value. The point is that I need to save in a program global variable what the user selects, and decide something with it in the program.
Is it possible that F4IF_INT_TABLE_VALUE_REQUEST FM returns the value in a sinple variable or it has to be paramter?
I look in a lot of previous threads but I didn't find anything, and I don't know if it's possible.
Thanks and kind regards,
MMP.

Hi,
Sure you can. All you need to do is to store what the function returns in your global variable. It don't need to be returned back to screen field.
DATA: BEGIN OF VALUES OCCURS 0,
         CARRID TYPE SPFLI-CARRID,
         CONNID TYPE SPFLI-CONNID,
       END OF VALUES.
DATA: VALUES_TAB TYPE TABLE OF VALUES,
          G_VALUE TYPE SPFLI-CONNID. "global variable to store what is returned
"in PAI first populate your table
SELECT CARRID CONNID
    FROM SPFLI
    INTO CORRESPONDING FIELDS OF TABLE VALUES_TAB
    UP TO 10 ROWS.
"then call the function but don't return the value to screen field
"If you specify the import parameters DYNPPROG, DYNPNR, and DYNPROFIELD, the useru2019s selection is
"returned to the corresponding field on the screen. If you specify the table parameter RETURN_TAB, the
"selection is returned into the table instead.
CALL FUNCTION 'F4IF_INT_TABLE_VALUE_REQUEST'
       EXPORTING
            RETFIELD         = 'CONNID'
            VALUE_ORG        = 'S'
       TABLES
            VALUE_TAB        = VALUES_TAB
            RETURN_TAB      = RETURN_TAB.
"now simply read first row of return tab and store the value returned there in some global var
READ RETURN_TAB INDEX 1.
MOVE RETURN_TAB-FIELDVAL TO G_VALUE.
Regards
Marcin

How can I access global variables in a loaded Applescript?

How can I access global variables in a loaded script, in Xcode, ApplescriptObjC? Basically, I have a global variable defined in my parent script using "property", and I need to modify objects connected to those variables inside of a loaded script.
Example:
Parent script:
script AppDelegate
property myTextField : missing value
//linked to a text field object
tell myScript to myAwesomeHandler_()
end script
Loaded script:
on myAwesomeHandler_()
myTextField's setStringValue_("The new Xcode is so glitchy ugh")
//changes value of linked text field of parent script
end myAwesomeHandler_
The problem is, the variable is undefined in the Loaded script, and I need it to have the same value as the parent script, and I don't want to pass the variable through the Handler. Any ideas?

I think want you are looking to do will need to be done in two steps. Because myTextField needs to be a property for the ObjectiveC part of the code you cannot turn it into a global.
However if you make a temporary variable global assign the string to it in the handler then set myTextField off of it.
global myTextFieldGlobal
script AppDelegate
property myTextField : missing value
//linked to a text field object
tell myScript to myAwesomeHandler_()
myTextField's setStringValue_(myTextFieldGlobal)
end script
on myAwesomeHandler_()
set myTextFieldGlobal to "The new Xcode is so glitchy ugh"
//changes value of linked text field of parent script
end myAwesomeHandler_
I know you stated you did not want the handler to return a value but I have to ask why? Global's, imo, are not a good idea and really should be used as a last resort.
One other possibility is to pass a reference to the property to the handler. Not sure if that works in AS of if that would satisfy our requirement of not passing the variable through the handler
<edit>
Another though have you tried to define the property outside the script? That is
property myTextField : missing value
script AppDelegate
Not sure if that will work.
You might also want to have a look at Scope of Properties and Variables Declared in a Script Object

Function module Global variables not cleared from memory?

Hi,
This is may be simple & stupid question ( after posting 4242 posts ):)
" Declaration in TOP
data : begin of i_y1yatt occurs 0.
        include structure y1yatt.
data : end of i_y1yatt.
types: begin of t_yatt71.
       include structure yatt71.
types: tcode like sy-tcode.
types: dflag type c.
types: end of t_yatt71.
data : i_yatt71 type standard table of t_yatt71
               with default key with header line initial size 0.
This is code in the function module.
loop at i_y1yatt.
    move-corresponding o_y1yatt to i_yatt71.
    if i_y1yatt-werks eq 'N501'.
       move space to i_yatt71-werks.
    endif.
    append i_yatt71.
    " Here this internal contains the previous entry
    clear i_yatt71.
endloop.
This function module is called 25 times in a minute.
My problem is this
For example : 1st tranmission is called this fm with 50 records,
and 2nd tranmission is called fm with 10 records.
My results are showing
last record in the 1st transmission is still on the memory while calling 2nd transmission. ( Here in int table I_YATT71 still contains the 1st transmission's last records during the 2nd tranmission call)
As per my knowledge if each time calls comes in to fm all gloabl variables get cleared. but some how this not happening.
Anybody come across this scenario.
PS. I know i need to use clear statement within the loop as first statement.
a®

You must understand that when calling a FM, you load the entire function group into memory. IF there are global variables, then they are "alive" for the entire duration of the program execution. Meaning if you call the function numerious times, or even if you call another function within the same function group, the functions still have access to that same global variable space, so it must always be cleared manually by the developer at the required points. You can not rely on the runtime to clear the global variables at the end of the function call. So you should clear all you globals as the first operation in your function module call, if that is what is required.
Is this clear?
Regards,
Rich Heilman

Table Reference Global Variable

Similar Messages

Maybe you are looking for