Need features of global variables but want to avoid re-writing to memory

I am making a program with a number of simultaneous loops that will be sharing several variables. Most of the variables are of size 1 or small arrays, so I am not too concerned about the constant re-writings involved. However, I have one rather large data buffer (3D array containing 200Kb+ of data). The buffer will be of a set size. In the various loops, the buffer will be accessed for updates (generally with Replace Array subset), and read from to get average values and such. I'm using semaphores so that none of the loops interact negatively and lose data. In other programs I'd set this up with a shift register in the loop, but since the data is being used in separate simultaneous loops, it's no
t really possible to wire it up that way. I need some sort of memory-space that can be accessed from the various loops.
I guess in sorts, I need to be able to have global variable 'pointers', but of course I was told a couple of years ago at a LabView seminar that pointers was a bad word.

tbob wrote:
> As long as Labview is running, the LV2 style global will automatically
> retain its last value. Of course the very first time it is run, the
> value is undefined, so you should write to it before attempting any
> read.
I have one correction to make. The value of an unitialized shift
register on first load is not undefined but rather contains the
datatype's default default value. This would be False for booleans, 0
for numerics and empty arrays or strings.
Rolf Kalbermatter
Rolf Kalbermatter
CIT Engineering Netherlands
a division of Test & Measurement Solutions

Similar Messages

Need help on global variables / parameters

Hi friends,
Please let me know if there a way to see the list of global variables and parameters in a form.
Thanks
Joe.

I presume you mean at runtime, since at design time parameters are in the Navigator, and globals can only be created at runtime. But unfortunately at runtime there is no way to get a list of them, like you can with blocks and items. (There's no easy way to get other objects either, like LOVs, canvasses, etc., though most of them can be derived from properties of items). But let's say you thought you knew the name of a parameter or global and wanted to confirm it really exists. With parameters there is no solution; you can't use find_item(). With globals a common technique is the following:
t_name := 'global.var';
default_value('SoMe ImPoSsBlE VaLuE', t_name);
if name_in(t_name) = 'SoMe ImPoSsBlE VaLuE' then
-- the global did not exist!
erase(t_name);
else
-- the global did exist!
null;
end if;
And of course remember that globals are not owned by a form; they are visible to all forms that are running.

We need to deactivate 3 computers but want to keep 2. How do we do that.it just says deactivate all

We need to deactivate 3 broken computers but we want to keep 2 that work.how do we do that

You use the Deauthorize All function and then reauthorize computers as needed. It isn't possible to individually deauthorize a broken computer.
(88711)

Iphone 4 wont sync to itunes anymore. Itunes opens then a message comes up saying I need to restore it. I want to avoid doing this as I've noticed some of my purchases since updating itunes are missing from computer but they are on my phone.

I have reset my phone, put the latest updates on itunes and iphone and thought it might work then, but no luck. I am trying to avoid restoring it as I dont want to loose the data I have purchased that is missing off my itunes since I updated that. I'm not sure how to contact itunes to get my data put back on my itunes on computer. All my purcahsed data from itunes still comes up on my phone as it hasnt been able to sync to the update. DOes anyone know how to contact itunes to have bought data re-put back on. It comes up in my itunes acocount with the date and purchase number but these items are missing from my itunes purcahsed items. Weird?
I am on an imac. Is there anyway I can get around the issue of syncing again or should I just restore once I have contacted itunes about them deleting my paid for items! I feel very ripped off, its like buyoing something from target and having the manager come to your house and retrieve it! lol

Plawexki wrote:
... do you know if the contacts, photos, messages etc will be wiped?
Yes... Everything will be Wiped and Replaced with what is currently on Your Mac.
SYNCING with iTunes
See here > http://support.apple.com/kb/HT1386
From Here > http://www.apple.com/support/iphone/syncing/
You may find this information of interest...
Have a read here...
https://discussions.apple.com/message/18409815?ac_cid=ha
And See Here...
How to Use Multiple iDevices with One Computer

Is there a MapPoint Reader for the Mac? I need to work in MapPoint but want to be able to read them on my Mac.

My team works on HP/Windows machines so Map Point makes sense but I can't read what they are putting out except as ppt. slides.
Does anyone know a reader? I could not find one.

There is no MapPoint reader at all in the sense of opening MapPoint PTM files... not for Windows, Mac, iOS, etc.
Normally when I am working with clients and they need to view maps created with MapPoint, we write a macro to copy/paste all the interesting map views (might be all store locations or maps of territories) into Excel or PowerPoint and have some dropdowns or hyperlinks to add some interactivity as appropriate.. I've also written programs that publish all the maps to a web site. Let me know if this would be of interest to you.
Eric
http://www.MapForums.com

Using Global variable in Record Group

Hi,
I have a requirement where in I need to pull a column name from a table and then use that value in the select statement of a record group. I have tried using global variables but it is not working. Here is the record group I would like to use.
RG_DOMAIN is based on LOV_DOMAIN
SELECT :GLOBAL.DOMAIN_COLUMN_NAME, DESCRIPTION FROM
DM_T_DOMAIN_VALUES
WHERE DOMAIN_NAME := BLOCK.ATTRIBUTE;
In the Key-Listval I have a select statement in which does this :
SELECT DOMAIN_COLUMN
INTO :GLOBAL.DOMAIN_COLUMN_NAME
FROM DM_T_DOMAIN_RULES WHERE DOMAIN_NAME = :BLOCK.ATTRIBUTE;
SHOW_LOV('LOV_DOMAIN');
The problem is I am not getting the value I am just getting the Domain_column name. For example for Domain_name 'CALC_TYP' the Domain_column is COLUMN_10 and I just see COLUMN_10 my LOV when I want to see the value of COLUMN_10 from the DM_T_DOMAIN_VALUES table.
I tried using Name_in and Copy but not working. Can anyone suggest a solution?
Thanks

Francois ,
I tried this but I am getting error saying record group does not exist. Can you tell me what should I go in Populate_group... and show_lov..maybe I am doing something wrong?
Declare
LC$Req Varchar2(512) ;
Begin
LC$Req := 'SELECT ' || :GLOBAL.DOMAIN_COLUMN_NAME || ' FROM ....' ;
Create_Group_From_Query( rg_group, LC$Req ) ;
Populate_group(RG_DOMAIN); ?? --- is this correct?
Show_Lov(LOV_DOMAIN) ; -- and is this correct?
End;

Global variable in as3.0

I am doing something with flash cs3,I need to use global
variable in it ,but there is not global variable in as3.0,can
anyone help me ,thanks forever!

There is no global in AS3. But you can make values globally
accessible by
using static fields in classes. e.g.
// MyClass.as
package
public class MyClass
public static var globals = new Object();
MyClass.globals["hello"] = "world"
trace(MyClass.globals.hello);
// and if you want to simulate something a little
// closer to the AS2 _global object you can drop
// this into a top level in your class path
// global.as
package
public const global:Object = new Object();
global["hello"] = "world";
trace(global.world)

Using a global variable within a function

Hi all,
I'm trying to learn how to use global variables, but can't quite get it right:
Im trying to use two buttons, named UpButton and DownButton to control one global variable, p1
A text field, named "Value" displays p1.
Here's my code:
p1 = 0;
ButtonClick("UpButton", p1, 100,"Value");
ButtonClick("DownButton", p1,(-100),"Value");
function ButtonClick(ButtonName,Var,Increment,TextToChange){
                    sym.$(ButtonName).click(function(){
                    Var = Var + Increment;
                    sym.$(TextToChange).html(Var);
However, it seems to be treating p1 as two different variables.
Here's a link to the page to show you what I mean, apologies but this link wont work in google chrome because I'm using dropbox as a server temporarily
In other browsers you may need to click "Show all content" or similar to any security warnings...
https://dl.dropboxusercontent.com/u/83693404/ButtonTest/buttons.html
Here are the project files:
https://app.box.com/s/0shocivto8fl295h62uq
Any help greatly appreciated, sorry if this is a stupid question,
Katherine

Hi Katherine,
However, it seems to be treating p1 as two different variables.
Indeed, your code created two different variables in two different scopes (I guess it as to do with JavaScript closures, but do not ask me more, I am still a bit foggy about that idiosyncrasy ).
In JavaScript, a primitive parameter – this is the case here with p1, a Number value –, is passed by value. In other words, a copy of the value is made. Your code handles two copies of the value stored in p1.
This contrasts with an object parameter, which is passed by reference (address in memory), without copy. Your code would work if Numbers were passed by reference : the two Var (p1) would then point to the same address.
The intent behind your trial is a global variable.
1) Let us be as simple as possible :
Stage : document.compositionReady event handler
p1 = 0;
buttonClick = function( Increment)
p1 += Increment;
sym.$( "Value").html( p1);
Stage : DownButton.click event handler
buttonClick(-100);
Stage : UpButton.click event handler
buttonClick(100);
Without being preceded by the var keyword the variables are global.
So the Number variable p1 can be accessed inside function buttonClick.
And the Function variable buttonClick as well, is accessible inside click event handlers, everything (function definition +function calls) being inside the same symbol (Stage).
2) Now, suppose this is no longer the case : you want to access a variable from another symbol.
We create a new GraySquare symbol, instantiated both in the DownButton symbol (instance name DownSquare) and in the UpButton symbol (instance name DownSquare).
Stage : document.compositionReady event handler
p1 = 0;
sym.buttonClick = function( Increment)
p1 += Increment;
sym.$( "Value").html( p1);
The sym. prefix is now necessary to make the variable (here a Function, but you would proceed exactly the same with a String, Number or Boolean) accessible in other symbols.
DownButton symbol : DownSquare.click event handler
sym.getComposition().getStage().buttonClick( -100);
UpButton symbol : UpSquare.click event handler
sym.getComposition().getStage().buttonClick( 100);
From these other symbols, the sym.getComposition().getStage(). prefix is necessary to acces to our global variable (function).
The two examples are downloadable here : https://app.box.com/s/6vkyiqk7i8zwlw0j1wk1
Gil

Create local or global variables ?!

hey guys,
I want to use variables instead of wires , which one you suggest , local or global variables? and why ?
thnxxx alot

blue silver wrote:
I want to use variables instead of wires , which one you suggest , local or global variables? and why ?
In LabVIEW, the wire is the variable.
Local and global variables have their limited use in certain UI tasks, but lead to inefficient, error prone, and hard to maintain code.
Local variables create extra data copies in memory, which can be expensive
They break dataflow and thus lead to race conditions.
To "fix" the race conditions, you need to clutter your code with sequences.
... it's an evil cycle!.
Why do you think you need local and global variables?
If you "want" to use them, you are probably misguided. Typically, you should only use them if you "need" to! There are legitimate uses for them.
LabVIEW Champion . Do more with less code and in less time .

How to auto create a global variable with specific variable name in a global vi ?

how to auto create a global variable with specific variable name in a global vi using lv ? Because i need to add a lot of global variable in this global vi. But you know, if i manually add them , it will be a much time-costing work. So i want to use someway to auto generate ? Can i ?? Thanks a lot !

Hi
what aartjan is saying is the way for you. but you can develop an utility which will actually help you create global variables. To get the details on this just have a look at VI Scripting section on LAVA forum.
But i would like you to suggest few things
1. If your programs have so many global variables (Thats why u want utility) then you should take out some time to read about LabVIEW design patterns. I think if programmer follows these practicess he dont need a single global variable.
2. Their are some other ways to achieve similar functionality as of global variables (Uninitialized Shift Registers, Single Element Qs and so on) but they are much faster than global variables.
I am Attaching Whatever Resources i am having I will also attach the template of the design pattern i generaly use in short duration
Message Edited by Tushar Jambhekar on 10-06-2005 07:33 PM
Message Edited by Tushar Jambhekar on 10-06-2005 07:36 PM
Tushar Jambhekar
[email protected]
Jambhekar Automation Solutions
LabVIEW Consultancy, LabVIEW Training
Rent a LabVIEW Developer, My Blog
Attachments:
LabVIEWDesignPatterns.zip ‏1505 KB
Large_Code_Implementation.zip ‏522 KB
Database Tests.zip ‏868 KB

Global Variable in Storage Package.

Hi,
I have one storage package with global variable.
if others procedures (in package) change this variable, in other sessions, it will not have the init value.
I need reset this global variable.
please help.
thanks.

Hello
Variables in packages are only visible to the session they are used in i.e. each session that uses the package gets it's own "copy" of the package and it's variables. If you want to share data between sessions you could look at global application contexts :
http://download-west.oracle.com/docs/cd/B14117_01/server.101/b10759/statements_5002.htm#sthref4478

Duplicate sub vi with the same global variable

This is a simple question, that probably was answered before:
I had a sub vi that uses a global variable. Now I need two of these sub vi's working simultaneously in a while loop. The problem is that they are both adressing the same global variable, but I need them to be isolated. How do I do that?
Thank you.

Hi Ivan,
This Developer Zone article explains a little more background about why functional global variables are the best option for you. Happy coding!
Amanda Howard
Americas Services and Support Recruiting Manager
National Instruments

Stopping a subvi from the main vi with a global variable

Hello,
I want a vi and a subvi to stop simultaneously. Thus, I created a global variable, STOP, which I connected it with the stop of the main vi and also with the conditional terminal of the subvi. However, it doesn’t work. Could somebody explain where am I wrong?
Thank you in advance
Attachments:
STOP.vi ‏4 KB
subvi.vi ‏5 KB
main.vi ‏6 KB

Hi,
You are making 2 mistakes. The first is that you didn't temporize the loops. The second is that when you launch the main VI this straight away launch the subvi that get the control and don't release till something change the value of the global variable, but in that time the main isn't running, so even though you press the stop button the main is in not running mode and doesn't change the variable.
Try this with the VI server to pass trough the control between two VIs.
Ricky
Italian Developer engineer
www.www.selt-sistemi.com
Attachments:
main.vi ‏9 KB
STOP.vi ‏4 KB
subvi.vi ‏9 KB

BADI for BI Global Variables in Reporting

Hi all,
We have requirement in our project like, we want to write BADI for all BI Global Variable. As already Customer exit is available for all the BI global variable , but as there is limitation of IF-ENIF Statements in Include program of Customer Exit Function module , So we are planning to go BADI. Does any one have idea on BADI for BI global variable.
Thanks in advance

Kindly check below link for your kind information.
http://www.scribd.com/doc/40764652/SAP-BI-Global-Report-Variable-User-Exit-Modularization
http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/60e34f63-f44c-2c10-488e-c89b04e0ca7c?quicklink=index&overridelayout=true
How to declare Global variable in BADI
http://www.sdn.sap.com/irj/scn/go/portal/prtroot/docs/library/uuid/30de01e0-b6f5-2b10-fba1-b9193b82da2a?quicklink=index&overridelayout=true
Re: virtual keyfigure using BADI
Regards,
Kamruz

Storing DAQmx Task in a Functional Global variable

Happy New Year to everyone!
I got a nice little question hoping some of you might be able to help me....
After initializing an starting a DAQmx task (V7.5), I wanted to store the task out reference in a functional global variable, but it seems, it didn't work.
Everytime I tried to call a DAQmx VI with the opened reference, I get an error, the task would not be existing....
I already made a workaround, so everything works fine. I'm just curious what I made wrong....
Thanks in advance!
Cheers
Oli
Programming languages don't create bad code, programmers create bad code....

Helo Oli,
Normally, you should not have a problem storing a task reference in a variable. However, the vi that created the task has to stay in memory for it to work. Closing the vi will result in the destruction of all created hadles -
that is why your reference might be regarded invalid if you use it in
another vi.
That is why I can just assume that you are closing the VI that created the task before you are using the handle somewhere else. You can use variables to store the task ID, but as a workaround you have to keep the vi which reated the reference running.
Hope this explains the behaviour.
Regards
Ingo Schumacher
Systems Engineer Sound&VibrationNational Instruments Germany

Need features of global variables but want to avoid re-writing to memory

Similar Messages

Maybe you are looking for