Call-by-value and call by reference

Similar Questions

• Threading and reuse of the node to call using reference of buffers (of the required adhesive tape)

  I tried to get the following information in the public domain for years and now that I have the answers, I'll share with those who might be interested.

  Caveat!

  Wrap your head in tape before reading just for the sake of security.

  My two questions were;

  (1) may LV re - use tampons of VI calling when you use VI serve call by reference?

  (2) is used when the use of call by reference UI thread?

  

  1 when you call a VI using the call through the reference node, the data in the pane of the copied or is node connector - this online as it would be with a Subvi properly implemented?

  Short answer: it's somewhere between the two.

  Long answer:

  The compiler does not know what will be called VI, but there a hint:

  the reference connected to the node of the call by reference. He uses to get the 'Prototype' for the call. Therefore, for optimal performance, use a prototype that has the same 'characteristics placeness' as it is called VI. That said, users don't know what are the "characteristics of the placeness.

  Before getting into the details, I will say that the overhead of these copies should not matter much unless it's a large data structure (a table with lots of items.) or a cluster/class with many fields or containing large networks etc..

  Example 1:

  If the prototype does not change the data, then the compiler assumes that the crux of the call by reference will not alter the data. However, at runtime, a check is made to see if the real called VI will modify the data. If Yes, then a copy is made and past so that the original data can be modified.

  Example 2:

  If the prototype contains an entry that is wired through an exit so that both input and output terminals can use the same buffer memory, but running an audit determines that the real called entry and exit VI do not share a buffer, then a copy will be made from output of the actual call to the original screws (combined input and output) buffer.

  I should also mention that, even with this behavior "are trying to get along with the prototype", it is not always possible to obtain good performance as a Subvi ordinary call. For example, if you have a situation where the prototype does not change the data and passes it through to an exit and then the compiler must assume that the data is changed (because, as in example 2, there are screws that may change even if the called real VI is not).

  And there are a few caveats:

  (1) this behavior "using a prototype" was new for 2009. Before that, we used a method more naïve data of passage that took all the entries will be changed and no outputs don't share a buffer with an entry.

  (2) this behavior can be changed in future versions, if we find additional optimizations.

  (3) this behavior is the same that we use for the dynamic distribution live (when you use the classes in LV)

  (4) If you want to create a VI can be used as a prototype, you can use the features of the Structure in Place to control the "characteristics of the placeness', namely the element nodes in and out of the border, the function"Mark as modifier"border nodes (note the pencil icon on the item), and the node always one copy.

  (5) the prototype is only the first reference ever connected to the node of the call by reference. So if you make a new prototype VI, you can just make a reference out of it plug into the crux of the call by reference. I suggest to remove the node from the call by reference and file a new.

  (6) for remote calls, we still "making copies" by transmitting data over a network.

  I hope that this helps, if you want information/clarification, so feel free to ask.

  2 - is the call made by the reference to run in the user interface thread node? If the call is made by a remote machine via ethernet, thread that host (the computer that makes the call by reference) runs on and thread that executes the target (the machine that contains the file VI) on?

  In the case of premises, the appeal made by the reference node does not require the user interface thread and may work in some thread the VI wants to run in.

  When you call a remote VI, the appeal made by the reference node uses the UI thread (detailed below) on both the client and the server.

  The client uses the UI thread to send the request to the server and there still when the response comes back. The user interface thread is not blocked during the time between the two.

  The server receives the TCP message in the UI thread, and then starts the call to the UI thread. The server also uses the user interface thread to send the response to the client. The user interface thread is not blocked on the server during execution of the VI.

  I hope that people find it when they need it!

  Ben

  
  

• call by reference and UI VBAI

  Hello

  I am trying to build a table (recipe_array_mod.vi), in which using the top and pressed, activate the cursor to navigate the table and load the corresponding data in indicators and I got also will add a new recipe and information to load data. I got to the point where my VI for recipe_array_mod.vi works very well, however, so that this code works on the withour of UI custom VBAI thrown exceptions for all dependencies, I started to look in the reference method call using VI server. I'm new to labview and reading about the VI call by reference, environment type specifier VI refnum shows type of connector information. But I see no information on connectors when using this method. Do I need to have a full version of labview to exploit this method?

  Please look into this and give me some feedback and corrections of code to use it with an interface user custom VBAI.

  Thank you

  Here is an example of update. She is the nice user interface that you want the main VI and it dynamically calls the subVIs who are working with file i/o and using VI server dependencies (which are primitive screws so that they are not counted as dependencies). You need to update the path to your sub VI in the main VI and you must make sure to close the Ref VI in the State of cleaning of your inspection (comments in the code of the main VI explain this).

  Hope this helps,

  Brad

• Data transmission between screws using call of reference without actually executing the vi

  Hi, I was wondering if you can pass data between the screws by using call of reference without actually executing the vi (ie: not having the façade appears during execution). Is this possible?

  While I'm here I might ask as well on the transmission of data between the screws I'm trying to pass a flag to a vi value to another. Because of the way the program is setup, I can't wire this value directly. Y at - it another (fast/efficient) way to pass data between two screws during execution (other than shared variables). For what it's worth this application will be built into an executable file, so data transiting will have to work for it as well.

  Thank you

  Vlad

  Vlad P wrote:

  While I'm here I might ask as well on the transmission of data between the screws I'm trying to pass a flag to a vi value to another. Because of the way the program is setup, I can't wire this value directly. Y at - it another (fast/efficient) way to pass data between two screws during execution (other than shared variables). For what it's worth this application will be built into an executable file, so data transiting will have to work for it as well.

  You have the choice:

  • shared variables (as you mentioned)
  
  
  • global variables
  
  
  • queues
  
  
  • notifiers
  
  
  • control references and properties of the value
  
  
  • action motors
  
  
  • ...

  Tell us a little more about your applications. What should do?

• Call in reference to replacement VI

  I'm doing a VI dynamically a reshipment that accesses a property in a class with name. (see attachment) The idea was to use 'call of reference' for the property required to call the correct data VI member access. The CBR does not preserve the dynamic wire of the input to the output, causing the VI must be broken. (see second attachment)

  Two questions: first, why it does not work? I understand that Labview must ensure this type of performance is preserved by a dynamic send substitute VI, but why couldn't you just take and raise an error if the type is not maintained? Secondly, any ideas how to get around this limitation?

  I agree that people can be so rude.  So ungrateful too.  What is the youth of today come at all.  I have really no idea.  The future is surely doomed.  Cursed I say!

  Now back on topic...

  Why don't simply implement you a class method rather than load a VI member by reference?  Simply, I do not understand the role of the party "by reference" here.

  If you MUST go this way (which I doubt at the moment) so please plan why call a DD VI dynamically is a requirement.  In the meantime, insert a primitive 'Preserve the class Run-Time' on the output of your dynamic call.

  That COULD help.

• VI, stuck to the call by reference

  Hello

  I currently have a problem of Subvi "call by reference. I am currently working on a datalog VI that takes a cluster (hidden as a Variant) and the writing of the elements in a text string. If the cluster contains a cluster VI datalog is called. When all the elements are written in the text string is written to a file and the text string is disabled.

  Here, I need reentrante run - so I am currently using property VI "re-entrant execution clone shared" and a "call by reference" with "Reload every call" to call him VI self. This was work up very well, but yesterday, after about 5 hours, the program is stuck at "call by reference. Have I set up correctly?

  Concerning

  Mark

  
  

• Main vi sharing of sub vi with call-by-reference - how?

  Hello

  as mentioned in another thread (http://forums.ni.com/ni/board/message?board.id=170&thread.id=390355), I have a main vi with a stop button and a under vi, who needs a few seconds to complete.

  During the execution of the Sub vi, I want the stop button in the main vi take effect immediately, which means the sub vi must stop immediately.

  I know that I can exchange data between screws somehow by a call to reference, but all the examples I found, to transfer data from the sub to the main vi vi, but I want the other way around.

  Given that I've never used the call by reference, I have no idea how I can do it.

  Attached you find, what I've done so far.

  I would be very happy if you help me and show me how to use the call by reference correctly.

  Johannes

  LabVIEW 7.1 (I used to program in C and Labview 6)

  Win XP

  Johannes

  I solved it!

  A reference and a property node t - it.

  See attachment

  Johannes

• check the type VI for call by reference node

  Hi Ppl,

  I call a set of VI dynamically using call-by-reference node. And I have a type specifier linked to a component of a particular type connector. But at the time where the VI prototypes do not math I get the error from the open VI reference node. Is it possible to check if the components of connector VI matches before opening the refrence with the specifier of type VI?, or by using the error code is the only way to check if there was miss match to component connector VI.

  Thank you

  But what is the problem with error control?

  For example, I use the code like this in my application to detect what type of Dynamics VI should be used (decision based on the error output):

  

  Andrey.

• DLL, interfacing with which coexist value and reference types

  Currently, I'm working with a supplied DLL.

  I have header files and everything and the DLL import wizard does a decent job of importing DLL functions but there are certain types of data that cannot simply be dealt with.

  The DLL requires the use of a data type that is a structure with data reference and value types.  I could theoretically replace the references by simple U32s, but much of the information required in the data is in the data referenced by the pointers structures.

  How can I do to implement this light how do I have to be able to transmit data to the DLL in its original form (value and reference types).

  I have something like the following:

  struct point {}

  Int device,

  * The point then

  * Previous item

  * Data Datastruct

  }

  I downloaded the Microsoft WDK, CVI and Visual Studio 2008 available.  I'm not very experienced in this end of things...   I will dispose of Structs with pure value types, but how do I get the data in reference types?

  I strongly suspect that I need a wrapper DLL, but how is the best way to go about this?

  Shane.

  Shane,

  It's always a problem when you use a DLL.

  If you do not have the sources of the DLL, you must trust the description of it.

  (Or you will have to disassemble to be sure, which is forbidden in most cases )

  If (in your case), the linked list is handled elsewhere than your Labview code, you will get in trouble. (Added, deleted, or modified items)

  I don't know your DLL. But usually the data is stored inside the DLL. For example, I have a DLL function that reads a counter from a DAQ hardware. If I reset it (on its reset settings), it sends back the nuber of counted events. This DLL must not be initalized.

  Other hardware DAQ I use must be initalized using its DLLS before you read all the values.

  It all depends on the implementation of your DLL.

  You have a detailed description of your DLL?

  Balze

• How to interpret the orbit and Point of reference Timebaseplot

  Hello

  the plot of the orbit and the time base includes a "red dot" called the reference point. I really didn't understand this meaning.

  Please, take a look at the photo "orbit_timbase_plot. PNG ".

  Thanks a lot for your help!

  SVX orbit and the basic plot of time (filtered) (Ch N - M orders) .vi accepts the size of entry and entry order height OATS phase and Phase (Signal the same Angle, N channels) .vi.

  If you want to extract the information from the phase of the red dot, you can just get the 2D cluster table 'phases' [lag phase].

  When "bandwidth [command]" is set to 1, and 'selection of the category axis' is set to the time, the 'phase' table in ' phases [offset] "corresponds to the phase of each red dot, the" time/rev/rpm"table in" phases [offset] "corresponds to the value of data orbit/time base reference.

• Get the old value and the new value based on the date

  Hello
  
  I have a table called list created below with the rest of the insert statements.
  
  CREATE TABLE ROSTER
  (
  NUMBER OF ROSTER_EMPLOYEE_DEF_ID
  NUMBER OF EMPLOYE_ID
  NUMBER OF DEFINITION_REGION_CODE
  NUMBER OF DEFINITION_DISTRICT_CODE
  NUMBER OF DEFINITION_TERRITORY_CODE
  START_DATE DATE,
  END_DATE DATE
  )
  
  
  
  INSERT IN THE LIST
  (ROSTER_EMPLOYEE_DEF_ID, EMPLOYE_ID, DEFINITION_REGION_CODE, DEFINITION_DISTRICT_CODE, DEFINITION_TERRITORY_CODE, START_DATE, END_DATE)
  VALUES
  (1,299,222,333,444, 'JUNE 1, 2011', 30 JUNE 2011 "")
  
  INSERT IN THE LIST
  (ROSTER_EMPLOYEE_DEF_ID, EMPLOYE_ID, DEFINITION_REGION_CODE, DEFINITION_DISTRICT_CODE, DEFINITION_TERRITORY_CODE, START_DATE, END_DATE)
  VALUES
  (2,299,223,334,445, "1 JULY 2011', JULY 20, 2011" "")
  
  INSERT IN THE LIST
  (ROSTER_EMPLOYEE_DEF_ID, EMPLOYE_ID, DEFINITION_REGION_CODE, DEFINITION_DISTRICT_CODE, DEFINITION_TERRITORY_CODE, START_DATE, END_DATE)
  VALUES
  (3,299,224,335,446, 'AUGUST 1, 2011', AUGUST 30, 2011 "")
  
  INSERT IN THE LIST
  (ROSTER_EMPLOYEE_DEF_ID, EMPLOYE_ID, DEFINITION_REGION_CODE, DEFINITION_DISTRICT_CODE, DEFINITION_TERRITORY_CODE, START_DATE, END_DATE)
  VALUES
  (4,300,500,400,300, 'JUNE 1, 2011', JUNE 20, 2011 "")
  
  INSERT IN THE LIST
  (ROSTER_EMPLOYEE_DEF_ID, EMPLOYE_ID, DEFINITION_REGION_CODE, DEFINITION_DISTRICT_CODE, DEFINITION_TERRITORY_CODE, START_DATE, END_DATE)
  VALUES
  (5,300,501,401,301, "1 JULY 2011', JULY 20, 2011" "")
  
  
  In the table above we have columns like
  
  EMPLOYE_ID, DEFINITION_REGION_CODE, DEFINITION_DISTRICT_CODE, DEFINITION_TERRITORY_CODE, START_DATE, END_DATE
  
  The result I'm looking for the table above is based on the employe_id OF start_date AND end_date
  
  I need to get the OLD_DEFINITION_REGION_CODE and the NEW_DEFINITION_CODE
  Similarly, OLD_DEFINITION_REGION_CODE and the NEW_DEFINITION_REGION_CODE
  and OLD_DEFINITION_TERRITORY_CODE and the NEW_DEFINITION_TERRITORY_CODE
  
  
  I need to get a row of data for each employee saying old value and the new value
  
  for the employee 299 there are 3 records he puts the new record which is the latest date is to say beginning August 1, 2011 and end date of recordings old 30 August 2011
  beginning July 1, 2011 and July 20, 2011
  
  
  For the data in the table above, I need to get the data as below
  
  
  EMPLOYE_ID OLD_DEFINITION_REGION_CODE NEW_DEFINITION_CODE OLD_DEFINITION_REGION_CODE NEW_DEFINITION_REGION_CODE START_DATE END_DATE
  299 223 224 334 335 20 JULY 11 30 AUG 11
  300 500 501 400 401 20 JUNE 11 JULY 20, 11
  
  
  Please suggest me to get the result above, based on the data. Please let me know if my messages are not clear
  
  
  Thank you
  Sudhir

  SELECT  EMPLOYEE_ID,
          OLD_DEFINITION_REGION_CODE,
          NEW_DEFINITION_REGION_CODE,
          OLD_DEFINITION_DISTRICT_CODE,
          NEW_DEFINITION_DISTRICT_CODE,
          OLD_DEFINITION_TERRITORY_CODE,
          NEW_DEFINITION_TERRITORY_CODE,
          START_DATE,
          END_DATE
    FROM  (
           SELECT  EMPLOYEE_ID,
                   ROW_NUMBER() OVER(PARTITION BY EMPLOYEE_ID ORDER BY START_DATE DESC) RN,
                   LAG(DEFINITION_REGION_CODE) OVER(PARTITION BY EMPLOYEE_ID ORDER BY START_DATE) OLD_DEFINITION_REGION_CODE,
                   DEFINITION_REGION_CODE NEW_DEFINITION_REGION_CODE,
                   LAG(DEFINITION_DISTRICT_CODE) OVER(PARTITION BY EMPLOYEE_ID ORDER BY START_DATE) OLD_DEFINITION_DISTRICT_CODE,
                   DEFINITION_DISTRICT_CODE NEW_DEFINITION_DISTRICT_CODE,
                   LAG(DEFINITION_TERRITORY_CODE) OVER(PARTITION BY EMPLOYEE_ID ORDER BY START_DATE) OLD_DEFINITION_TERRITORY_CODE,
                   DEFINITION_TERRITORY_CODE NEW_DEFINITION_TERRITORY_CODE,
                   LAG(END_DATE) OVER(PARTITION BY EMPLOYEE_ID ORDER BY START_DATE) START_DATE,
                   END_DATE
             FROM  ROSTER
          )
    WHERE RN = 1
  /
  
  EMPLOYEE_ID OLD_DEFINITION_REGION_CODE NEW_DEFINITION_REGION_CODE OLD_DEFINITION_DISTRICT_CODE NEW_DEFINITION_DISTRICT_CODE OLD_DEFINITION_TERRITORY_CODE NEW_DEFINITION_TERRITORY_CODE START_DAT END_DATE
  ----------- -------------------------- -------------------------- ---------------------------- ---------------------------- ----------------------------- ----------------------------- --------- ---------
          299                        223                        224                          334                          335                           445                           446 20-JUL-11 30-AUG-11
          300                        500                        501                          400                          401                           300                           301 20-JUN-11 20-JUL-11
  
  SQL>  
  

  SY.

• Problem LOV... Turning the display value and no key-value

  Hello. Sorry for my bad English.
  
  I have a problem with LOV dynamic pop up.
  
  I have a simple form called nom_element and item_code containing the form A. users can create, update, and delete a new item using this form.
  Another form called form B has a field called item_code item_code is a dynamic field of LOV pop up and a request for this LOV is like that;
  
  Select nom_element d, r from item_master by item_code item_code;
  
  When I create the new record in the form B and LOV allows to find and get the item code, LOV works very well
  and he returns the key value in the field of item_code.
  But when I try to update the record (I have a link to the page of the form B), item_code field value is not the key-value of LOV, but is a
  Display value of LOV.
  
  Any ideas?
  
  Thank you.

  Hello:

  If you want to display the key value, and then create a new field that can be a test field or a tabled text (display only) and assign the value of the column of the reporrt link or just the column as it appeas in the database.

  If you use the form at the same time create and view, you might want to do this new field, but also your LOV field as conditional.

  Bruce

• Get the Max values and average of the different cycles in the single channel

  Hello

  I'm trying to get the Max values and average of the single channel that has different cycles it contains. I tried to use commands such as Chnclasspeak3 and chnpeakfind, but they were not useful for me. What I need is the Max values and average of the different cycles numbers saved in the data channel.

  Exampld if the string contains 5 numbers of repetitive cycles, then we must find the maximum values and the average of these 5 cycles in the single channel. Attached reference data. This is the .raw file and I have the plugin for it to use in diadem 11.1.

  Kind regards

  X. Ignatius

  Hello, Ignatius,.

  Sorry, it took some time to provide a replacement based on the script for the function. Please take a look at the attached script. I changed the script to use my function if the tiara-version is less than 12. My script function is not as fast and more stable than the implementation of tiara, but for now, it does the job

  Andreas

• Change of values and change when you save a picture BW

  Hello community and first of all Merry Christmas to whom it may apply

  I am trying to solve this problem by doing my own research, but I work against the clock and I found no specific useful information so far.

  I'm sure he can have to do with the profile settings, but frankly, I'm a little lost.

  Here it goes:

  • I have these black and white photos I shot, which I first edited in Lightroom, (RAW images. CR2) and then decide to take them to Photoshop for some finishing touches so I use "Edit in...» Function of Photoshop"in Lightroom.
  • At the opening in Ps, I get the usual profile of the conversion options (my Lr settings are ProPhotoRGB) so I decide to convert the photo of my Ps work space: Adobe RGB (1998).
  • So far so good, on the surface, like comparing my pic between Lr and PS, virtually identical.
  • I have to put it back end in Mode files: grayscale /. Hair, so when trying to save with (and frankly, any other) extension, the problems start: final result varies quite considerably in values and working space Ps rendering tones (and of course, the 'original' Lr edited pic)

  I tried a lot of combinations (and the box of grain dot checked and unchecked in the file save dialog box) color profiles and settings, but I'm going crazy here...

  Any suspicion or any brief reference where I can learn at this address will be more than welcome. Time is NOT on my side (talk about season Hollidays ha!)

  Many thanks and best wishes to all!

  A simplified workflow:

  Adjust the RAW image and save as TIFF 16bitperchannel (PCBs) in AdobeRGB.

  Modify as necessary in Photoshop.

  Convert to TIFF 8bpc and save as a TIFF.

  Convert grayscale with GrayGamma = 2.2 and save as a TIFF.

  Most likely the error is the result of the settings of tones "confused."

  In fact the tones is based on a (TRC) tone reproduction curve.

  GrayGamma = 2.2 uses the same TRC as AdobeRGB.

  Therefore work in Photoshop, with always embedded in profiles,

  all the parameters are properly taken into account. But other programs are subject to errors

  even if gray profiles are incorporated.

  In short: the workflow suggested reduced the risk of confusion.

  Cordially - Gernot Hoffmann

• Displaying an Enum value and the name of the element when the values are not sequential

  Hello

  I use Enum and controls indictators successfully with shared and modbus variables.

  For example:

  Name of the element Value

  Off:                0

  Start 1

  On                2

  Œuvres enum Setup, I don't need to look for a cheat sheet to convert the name of the element in its value, I see the name of the item in my order/indicator.

  My new variables, I'm currently managing look like this:

  Name of the element Value

  Code 0 x 201

  Beginning Code 0 x 202

  Code 0 x 001

  Any ideas how I can display the value and the name of the element on a façade. (for a control and indicator)

  For enumerations, it seems that the item values must go 0,1,2,3,4,5

  I found the solution:

  http://digital.NI.com/public.nsf/allkb/79BA4505AE8C755E86256FB2000140B0

  use a ring of text and deselect the sequential box