Global variables or shared unique process variables?

Similar Questions

• variable shared unique process - build executable

  I have two applications on the same computer. Single process variable using shared with both applications. When generating executable writer updates the shared variable but the VI read the shared variable does not read the values. The question is only when you create and run executable files. How to build two executables on the same computer (and both are in the same project) using shared variables unique process?

  The use of the network shared variable is not necessary that both applications are on the same computer but when building executable with network shared variable that it works, only the shared variable unique process does not work?

  TIA

  Only shared process Variables work in the same application context.  When you are developing and the two screws are in the same project, they are in the same application context.  But two executables will be different application context.  So to communicate between two executables, you use shared network variables.

• LV/CVI how can I access variables 'unique process' shared by his name?

  LabviewCVI 9.0, how can I access a variable shared 'unique process' by his name?

  Hi jenstl,

  If you are referring to a LabVIEW shared variable project unique process, then I don't think that you can access it (directly) from the CVI. As its name suggests, the variable is related to a single process, i.e., LabVIEW.

  If you want to share a variable between LabVIEW and CVI, you could try a shared Variable of published network. Not only is it really easy to convert a process unique to a network shared Variable shared Variable, but there is also an example on their share between LabVIEW and CVI.

  Community: CVI and LabVIEW shared Variables published network

  For more information on Variables shared:

  Developer Zone tutorial: use the LabVIEW shared Variable

  Also, I originally said that you cannot use a single shared Variable directly from the ICB process. I added the 'directly' in there because in all likelihood, you might happen to a (potentially convoluted) workaround involving the use of ActiveX to call the LabVIEW ActiveX Server and communicate to the Variable shared in this way.

  Hope that helps!

• How a shared single process variable be FIFO and single element?

  How a variable shared unique process can we both FIFO and the only element at the same time?

  I read the NOR recommended for communication between a loop deterministic and non-deterministic loop.  He is said to use SVariable ingle-process Shared FIFO and single element.  OK I can't have something... because in my mind these two things must be mutually exclusive.  How do you have a single item 1?

  

  What 'RT FIFO activé' means, that when you use the variables shared in a timed loop it actually is written to a RT FIFO created automatically.

  The key here is that generally shared variables are shared resources and can add jitter to deterministic tasks if another loop uses the variable at the same time as your loop of deterministic.

  So here's the takeaway, when shared with RT FIFO active Variables using:

  • Normal loops read and write the shared variable in the same way as they always do.
  
  
  • Call loops read and write a FIFO RT rather
  
  
  • The data is automatically passed between the RT FIFOs and shared in a nondeterministic loop variable

  RT FIFOs exist because their architecture referred to as non-blocking so that when the timed loop trying to access it is guaranteed immediate access to a memory space.

  Does that answer your question?

• Variables of unique process and EVS?

  Hello

  I used variable shared unique process and shared network variables in a project with a host PC and a cRIO.

  Is it possible to host the variable engine shared on the PC and still have the cRIO using process variables unique shared when the PC is turned off, and therefore the EVS is not available?

  Reading the documentation, I think it's okay, but I don't know, I'd check myself but the cRIO isn't available .

  Thank you very much

  Steve.

  Hello Steve,.

  Here is a link to a KB which has a note that a shared variable unique process does not use the Shared variable engine.

  http://digital.NI.com/public.nsf/allkb/1F45A4298B976F4A86257168006EA0C3?OpenDocument

  The reason is that it would add additional overhead to the application.

  One thing to remember of thought, it is that when the VI on the cRIO comes to use a shared variable of the network and the engine is not available this VI will throw an error.

  With respect,

• global variables shared between several targets of RT

  Hello

  I'm looking for some information about variables shared between RT communication network.

  Scenario: a PXI 'master' and several 'slave' PXIs running that screw RT. data is available in the form of a cluster of definied type on each slave PXIs (inside a non deterministic while loop). I guess I create global variables of network shared for each PXI slaves. A variable for each slave. I only write data in these variables in one place (above mentioned, while loops), on the PXIs slave. I need to read that data in a way with loss (I just need that value the most recent, as tags) from the master PXI.

  Question: can I simply use "network shared variable" settings by default? I mean, I do not enable the option RT FIFO (single element), because I think that for a cluster that is a no go in the case of RT (variable length)?

  What do you think? Or would you have better idea how to share data between slaves and masters RT targets (I do not have deterministic/losless transmissions, only these last values)?

  I think that the way to proceed is to use the shared Variable Aliasing/binding - they allow you to 'link' shared variables in any of the multiple targets. https://forums.ni.com/t5/LabVIEW/Bind-Alias-shared-variable-to-scan-engine-variable/td-p/3290043.

  You can also use shared variables of programming access to access running on another target: http://zone.ni.com/reference/en-XX/help/371361G-01/lvconcepts/usingdynvarapi/

  With regard to the other methods - you could always disseminate data via UDP multicast (or with a TCP/IP connection manager).

• How can Global variables can be shared in Subvi?

  I have a question about global variables. not found an answer in the Forum.

  I want to share a few global variables in the different Subvi: starting Subvi first hand.

  define variables, then in second vi, use these variables.

  In my test, if I run LabVIEW, everything is ok. If building an exe, the first sub - VI

  cannot be exited. If the output, the value of global variabels is deleted.  I don't know why?

  Can I use like this? Please help me.

  Thank you.

  attached is my main application. For the release of sub - VI, just call FP. Close.

  The way I underrstand problem:

  There is a main VI (main.vi) that will successively two different screws through a VI reference.

  Let's call them A.i and B.vi. The two access to the same global variable.

  The main VI does not have the global variable.

  At first is short, then closes. B later runs and is expected to access the global variable with the data left by an earlier. I haven't explored it, but I guess that once A ends, the global variable also leaves in memory, forgetting everything

  My suggestion is to place an instance of the global variable in the main VI, forcing them to remain in memory as long as the main VI is running. Apparenlty, this action solved the problem.

  mmm2006 wrote:

  Can I update a global variable in main vi? There are a lot of adjustment, and I don't want to display them.

  I guess it will be sufficient to place the global variable in the main VI to keep in memory. There is no need to read or view its content. Another solution might be to specify the global variable as 'start VI "? I have not tried.

  These are just speculation, because I almost never use globals so my experience is limited. I probably would have A.i write the data to a file B.vi later access, for example.

• APEX 4.2 translate data 'function and Global Variable declaration '.

  Hello everyone,
  
  I use APEX 4.2.1.00.08 and I wonder if there is a way to translate "Function and Global Variable declaration" textarea. Any other script text box is available for translation, but not this one.
  I know what the code is loaded on the header, but may contain important alert messages of global functions.
  
  Thanks in advance.

  Hi Grandmaster,

  "Function and global variables declaration" contains the JavaScript code, that is why it is not wise to include in the standard translation process.

  In my opinion, you have several options to access your translated messages:

  -) Use Application-> Substitutions or
  -) Store your message in the form of component shared-> SMS and and assign it to an application with the APEX_LANG element. Api MESSAGE (http://docs.oracle.com/cd/E37097_01/doc/doc.42/e35127/apex_lang.htm#CHDBCEAB)

  In 'Function and Global Variable declaration' use substitution syntax to replace the value. For example:

  var myDeleteMessage = "&G_MY_DELETE_MESSAGE.";
  ...
  alert(myDeleteMessage);
  

  where G_MY_DELETE_MESSAGE would be a part of the application or the request for Substitution.

  Concerning
  Patrick
  -----------
  Member of the APEX development team
  My Blog: http://www.inside-oracle-apex.com
  APEX Plug-Ins: http://apex.oracle.com/plugins
  Twitter: http://www.twitter.com/patrickwolf

• Setting the value of an element of Application (defining a global variable);

  Apex 3.2.0.00.27, I need to initialize a global variable to 0 to implement a variable to test to see if something on the page has changed. Will update to 1 when some lists of selection on the page are changed. Read through a few similar questions and answers within the forum, as well as blogs and other sites. So, I think that what I do is the way forward in this regard. Unfortunately, my point/global application initialization is not past yet. Here's an overview of what has been implemented:
  
  1) has created an element of demand, G_CLASSIFICATION_ID_NEW in the shared components.
  (2) created the Javascript (JS) function called by addLoadEvent area header html page so when the page is loaded, the application global/G_CLASSIFICATION_ID_NEW element should be set to 0 with the following JS and using AJAX and htmldb_GET:
  
  < script type = "text/javascript" >
  function initVars()
  {
  Alert ("before the initvars get");
  get var = new htmldb_Get (null, $x('pFlowId').value, null, 22);
  Get.Add ('G_CLASSIFICATION_ID_NEW', 0);
  gReturn = get.get ();
  {if (gReturn)}
  Alert (gReturn.value);
  }
  get = null;
  Alert ("after get initvars");
  }
  
  Alert ("before the call to the initpage");
  addLoadEvent (initVars ());
  < /script >
  
  I used the htmldb_Get successfully to populate other global variables and processes on request with onchange THAT JS call in the attributes of html form elements select list on the page. Later, I check the globals via the Session view and research on elements of Application. Unfortunately, I'm missing something, because my G_CLASSIFICATION_ID_NEW never gets filled when I load the page. The Alerts popup every when the page is loaded, so I know that the script is running when the page loads. alert (gReturn.value) is not defined. And, of course, the G_CLASSIFICATION_ID_NEW to 0 does not place.
  
  I tried the htmldb_Get with her call for a process of application and without (null value). What I read, you should not need to call an application process to have the get.add of the value of the global variable. Here again, this could be where I'm wrong. However, as I mentioned, it works for the other functions called from an onchange to fill a part of the application, but the page has already loaded when the onchange (s) executed. They can work because the page is already loaded when the onchange is called. My point here is that my other on application processes are NOT set or modify global variables at all. The globals are preparing with the get.add (< element app >, < value >) part of my other JS works within the HTML header area. So I'm inclined to believe that I don't need 'application_process = < some_odp >' set parameter, but if it is not true, please let me know. If so, what should be in the application process-that is to say, what would be the purpose of the get.add (< application item >, < value >) if I set the global variable in the application process on because it's the only thing I could think to do within an application process on for this?
  
  If someone can point out what I'm not understand or, failing to do it here, that would be great. I am doing fine with APEX, but don't consider myself a guru with it immediately. I'm certainly not a JS/AJAX guru, and when things like that, go astray, I get bogged down because I'm not sure of the problem. So, I hope that you gurus who monitor this forum can get going in the right direction.
  
  Thank you
  Bob

  Hello

  Create page 0 (zero) to your application.
  Then try this javascript in your HTML page header

  BR, Jari

• DLL and global variables

  OK, here's a strange problem.  I am very new to create the dll, so I don't know that I have just an installation problem.

  But I'm trying to pass a global variable of a host program to its attached DLL.  I got this job when I was the CVI 2014. I recently upgraded to 2015 and then started getting "undefined symbols" errors.  With some struggle I managed to compile again, but broke the variable connection in the process.

  I have compiled my DLL in debug mode so that I walk in from the test project.  Right now, my global variable exists in the test project, as well as in the DLL.

  Can I export the variable and the use of DLLIMPORT/DLLEXPORT?  Confused and curiously not to find anyone quite like this on the forums.

  EDIT: this post stack overflow described pretty well from my experience.  I am linking statically.

  Well, what do you know?  I found my problem.  This draft article and example WERE vital to the solution.  This article called, "using the Export method qualifier"was also useful.  I'll cut to the Chase...

  If you use a qualifier of export on the definition and the import on the declaration, LabWindows/CVI identifier export symbol.

  This is the right key.

  So in my example, it should look like this:

  DLL fichier.c

  int DLLEXPORT varName = 0;

  Header.h DLL

  int DLLIMPORT varName;

  Project that uses DLL.c

  #include "header.h DLL.
  
  varName! = 1 ;  a method to change this variable for local use

  Pretty easy, huh?  But wow, it took some time to find.

• How to extract file with LabVIEW Teststand global variables

  Hello

  My goal here is to extract all the contents of the global variables for file (names and the value of any types) in a sequence of my LabVIEW UI file.

  For now, I can only open a file of sequence of LabVIEW and get the number and the names of the variables (cf. vi) attached.

  But if my variable is a container, I would like to know all the contents of this container (and so on) and I don't know how to do it.

  In addition, I have to extract the value of variables that I don't know the type in advance...

  Can you help me?

  Thank you.

  Well I finally used the method "GetNthSubProperty" to work on each variable and I use the property 'Type' to know if it's a number, string, boolean, or a container. If it is a container, I repeat the process at a lower level... (see attached vi)

• global variable functional to read and write data from and to the parallel loops

  Hello!

  Here is the following situation: I have 3 parallel while loops. I have the fire at the same time. The first loop reads the data from GPIB instruments. Second readers PID powered analog output card (software waveform static timed, cc. Update 3 seconds interval) with DAQmx features. The third argument stores the data in the case of certain conditions to the PDM file.

  I create a functional global variable (FGV) with write and read options containing the measured data (30 double CC in cluster). So when I get a new reading of the GPIB loop, I put the new values in the FGV.

  In parallel loops, I read the FGV when necessary. I know that, I just create a race condition, because when one of the loops reads or writes data in the FGV, no other loops can access, while they hold their race until the loop of winner completed his reading or writing on it.

  In my case, it is not a problem of losing data measured, and also a few short drapes in some loops are okey. (data measured, including the temperature values, used in the loop of PID and the loop to save file, the system also has constants for a significant period, is not a problem if the PID loop reads sometimes on values previous to the FGV in case if he won the race)

  What is a "barbarian way" to make such a code? (later, I want to give a good GUI to my code, so probably I would have to use some sort of event management,...)

  If you recommend something more elegant, please give me some links where I can learn more.

  I started to read and learn to try to expand my little knowledge in LabView, but to me, it seems I can find examples really pro and documents (http://expressionflow.com/2007/10/01/labview-queued-state-machine-architecture/ , http://forums.ni.com/t5/LabVIEW/Community-Nugget-2009-03-13-An-Event-based-messageing-framework/m-p/... ) and really simple, but not in the "middle range". This forum and other sources of NEITHER are really good, but I want to swim in a huge "info-ocean", without guidance...

  I'm after course 1 Core and Core 2, do you know that some free educational material that is based on these? (to say something 'intermediary'...)

  Thank you very much!

  I would use queues instead of a FGV in this particular case.

  A driving force that would provide a signal saying that the data is ready, you can change your FGV readme...  And maybe have an array of clusters to hold values more waiting to be read, etc...  Things get complicated...

  A queue however will do nicely.  You may have an understanding of producer/consumer.  You will need to do maybe not this 3rd loop.  If install you a state machine, which has (among other States): wait for the data (that is where the queue is read), writing to a file, disk PID.

  Your state of inactivity would be the "waiting for data".

  The PID is dependent on the data?  Otherwise it must operate its own, and Yes, you may have a loop for it.  Should run at a different rate from the loop reading data, you may have a different queue or other means for transmitting data to this loop.

  Another tip would be to define the State of PID as the default state and check for new data at regular intervals, thus reducing to 2 loops (producer / consumer).  The new data would be shared on the wires using a shift register.

  There are many tricks.  However, I would not recommend using a basic FGV as your solution.  An Action Engine, would be okay if it includes a mechanism to flag what data has been read (ie index, etc) or once the data has been read, it is deleted from the AE. 
  
  
  There are many ways to implement a solution, you just have to pick the right one that will avoid loosing data.
  

• Problem of global variables

  I have subVI´s of multiples that send data to the VI main when are called using global variables. Then the main VI must send these data to an another subVI´s called by an another VI main to show in its facades. It works perfectly when all SIX are executed in the LabVIEW environment, but when it's in main VI´s generation aplication, it's as if the global variables do not work because the data are always zero... I can´t find the cause of the error, I checked the construction features and there is nothing about the global variables, only the VI that located them in the summary project dependencies.

  What could be the error?

  You can use shared variables, you cannot use global variables. Shared variables can be local (on a PC) or network.

• Is it possible to replace occurrences of a global variable massively while also setting up the components of connector?

  I work through some of my old code now, looking to increase the performance where I can. Here's my situation:

  1. I used Global Variables to spread a few constants in my screws, instead of a proper typedefed cluster.

  2. execution does not have an extension, but no matter when I save the project, I would say 50 to 60 percent of the economy/compling time is spent on the screw of 300 or more with global variables. I suspect it has to do with the link between the overhead associated with the global.

  3. Ideally, I would like to replace this:

  

  With something like this:

  

  While also putting the connector of this pane:

  

  To do this:

  

  What is the VI server is capable of? You can assume that the VI in question have very predictable names, matching the regular expression:

  subname[0-9]^3
  

  Is it still worth it to replace?

  I don't know what you mean by compile time.  One of my big projects LabVIEW RT, which has about a thousand of screws, a lot of VIGs (FGVs), engines of the Action, even a few Globals and variable shared.  In my case, the thing that seems to "slow down" the compilation the most is the links to the report generation tool (I use Excel workbooks for 'drive' of experience and also save the data a bit).  If I do a building together, to build this routine and about 6 'support' routines (data analysis, utility Configuration, etc.), it may take a minute, but I can't find this excessive nor a charge (compared to the facility to isolate/encapsulate features in screws as FGVs).  So I guess I don't understand the "real problem"...

  Bob Schor

• global variable in the instrument Drivers

  Hello

  We design an instrument Driver for our devices. We have VI that does the same thing, but with different inputs and this entry is a collection of references.

  I would like to know if this VI can be contributed by these groups as global variables. Through this way, I hope that we will significantly optimizie our code.

  We are also looking for drivers to achieve certification by the OR so looking for any sort of solution if global will not be a good solution to achieve the optimization.

  Thanks in advance,

  VIvek

  I don't understand what you mean by "chipped". Using global variables magically will not make your code more efficient. It is used for the global variable, and there are places where they should not be used. Reasonable use must contain the data used by several processes, even if a queue is usually a better way to go.

  The best way to see how to write an instrument driver is to download recent instrument of the NI Instrument Driver Networkdrivers. Look for ones that are based on projects like these are made in 8.x and are fairly recent. You don't have to bother with the old drivers - they are a mess. You should be able to find something that looks like your instrument and use it as a model. There is also a Driver of Instrument wizard that comes with LabVIEW. Another source of information is the basis of knowledge of NOR. Do a search and you will find a lot of information. Like this: developing LabVIEW Plug - and - Play instrument Drivers.

  You should also read on the nugget of Ben on the engines of the Action.