shared - variables multi-network

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• Shared Variable (published network) communication

  Hi all

  All day I was hitting my head with variable communication shared between RT host and the host computer:

  I basically tried to pass an array of the host of the CR to the host computer. For this I used a published shared variable of network type Array U64. I used this link to help me understand usign shared variable communication

  http://www.ni.com/white-paper/4679/en ...

  I also activated RT FIFO. Now in the city that link the information given on the use of FIFO of the single element or Multi element FIFO

  "By enabling real-time FIFO, you can choose between two types of compatible FIFO slightly different variables: the only element and the buffer insurance program. A distinction between these two types of buffers, it's that the only element FIFO reports no warnings on positive or negative overflow conditions. A second distinction is the value returned by LabVIEW when several readers read an empty buffer. Several readers the only element FIFO receive the same value, and the only element FIFO returns the same value until a writer writes back to this variable. Several readers of a FIFO empty array each get the last value that they read from the buffer or the default value for the data type of the variable, if they have not read before variable. "

  I had read the content above a 100 times, but still I'm not able to get a clear picture of the difference and when to use which option. So I decided to take the text and tried to try something for me.

  I had a loop in the reception of RT who writes arrays of 3 different elements in the 'network published variable shared'. Now when I use the option of multi element with "number of berries as - 2" I am able to read tables separates one by one in the host computer (as you can read a queue in general).

  Now when I used the option of single element for the RT FIFO with 1 UN editable table option, only the last table written in the 'shared variable published network' is read in the host computer.

  This seems absolutely ridiculous as if this is the case, then what is the purpose of creating the "buffer". For testing purposes, I had put the buffer in 5 tables.

  In fact, I have only a single author (written in loop in the reception of RT) and a reader (new looping in the host computer). So I don't know even if I need option of the RT FIFO for the published network shared variable.

  I'm sorry for the long message but I've reached the limits of going around in circles waiting to type somewhere

  I know I made a mistake stupid somewher or it miss me probably a clear simple trick but don't know what it is...

  I request some clarification... In fact I posted a little while earlier today so ... bind - http://forums.ni.com/t5/LabVIEW/RT-Host-to-Host-computer-communication/td-p/2348130 )

  any help would be appreciated

  See you soon

  me

  Hello

  I think that the difference between these two types is clearer by using LabVIEW:

  "

  Activation of the FIFO in real-time

  You can activate the FIFO in real-time to a shared variable since the page FIFO in real-time of the properties of the shared Variable dialog box. Check the box Enable the FIFO in real-time in a deterministic way share data using the one element or several elements FIFO.

  Single element FIFO

  One FIFO shares the most recent value of the data. The shared variable overrides the value of data when it receives a new data value. Use this option when you need only the most recent value. Configure the size of the elements of the array or the size of the waveform for the FIFO buffer, if you select a table or a waveform data type.

  Several elements FIFO

  A FIFO multi-elements implements buffer the values shared by the shared variable. You can configure the size and elements of the buffer FIFO to match the parameters of buffering to use of the Variable page, or you can configure a custom size for the FIFO and FIFO elements.

  Note  For single item both multi-elements FIFOs, if the variable contains data table or a waveform, you must configure the size of the elements FIFO equals the size of the data to share. If the network buffer both the RT FIFO are enabled, the network buffer should be at least as big as one of the elements of FIFO. Sharing data smaller or larger that the specified length results in a memory allocation which affects determinism.

  Note  Waveforms contain variant of varying size that are not compatible with real-time FIFO. Therefore, if you enable the FIFO in real-time on a shared variable that contains the waveform data, the item variant waveform data does not transfer.

  "

  http://zone.NI.com/reference/en-XX/help/370622K-01/lvrtconcepts/rt_projectvariable/#Single_Element_F...

  ' Hope this helps

  Aurélie

• writing in shared variable published network hosted on rt (defined as slave modbus for crio) problems

  Hello Forums or

  This is my first post on this forum and I've been using labview for about 8 months now

  I have a problem about writing data in the modbus registers through a server of e/s defined as a slave modbus for my hardware 9074. Once I finished the project of construction and deployment of the variables and by following the instructions here , he reports no results but a row of zeros. I have the DSM nor opened and configuration modbus master to see whether the data is actually read or written on the respective sides that give the same line of zeros so.  What I am actually trying to write is a single-precision floating data table. The registers are structured F40000-F46534 runs from 10 items or have them for range AF40001L1-AF46534L1 of the AF40001L10 point where it's an array of length 10. (Referenced beaches here)

  I know 1 thing for you, the modbus connection works and is ready for data requests, I tested cela NI DSM and set manually the data for and received my master.

  System and project specifications

  Windows 7 operating system

  LabVIEW edition development system complete 2011

  No module Labview DSC, but I use the real time such referenced by one of the documents

  This project is an application in real time with fpga mode (and not scan interface)

  The master and the slave are the same network and subnet

  Connection Modbus type: TCP

  9074 compact slots rio 8

  9234 module x 3

  module 9221 x 1

  9472 module x 1

  Engine service Variable shared running on windows os and rtos system

  Used this guide to learn more about the Protocol modbus, as I have searched all over the internet to learn more about modbus

  I already have software Modbus IO Server installed on the crio thanks to max or 1.8 for NI RIO 4.0 version

  file attachment (s)

  Image of software specifications Crio

  Image of data written in scheme-block rt variable

  Short version of the problem: why is the e/s no variable writes in with the converted correctly data?

  Okay, Yes, it's that I was the one proposed. Regarding the news of the error, if you look at the bottom of your image to DSM, you see a little commfail and an error code, but it seems that those are OK.

  The only thing I can think is that DSM (or another function) is written for a range of values that includes 400004. I suggest you to put into service 4-going to a range of 3. 3 s are entered only (perspective control), then you can be sure that the master is not trampling on the data. Once you have checked that, look at DSM and any other code running to make sure q EU not accidentally write 0s to the same reg.

• VI refuses to run when the published network shared variable is not available

  I have a VI of logging data on my PC that gathers data from several sources, including several shared variable published network hosted on an RT target.

  The problem I have is that the data logger VI refuses to start if the target RT is disabled and the VI is abandoned if the network connection is interrupted.

  Is there an easy way to detect when running, be published these variable network are available and use a placeholder value, if they are not rather than the current behavior of refusing to work?

  I saw many people using data sockets, but I try to avoid the overhead of setting up and testing a loop of treatment relatively complex network on both ends when the network has published shared variables are so simple to use and works perfectly as this abnormal behavior.

  You can replace them with programmatic access (shared variable aperture and friends) and the dummy data placeholders if the variable is not accessible.

• not possible to bind a variable shared via Ethernet network

  Hello!

  I have computer A and B with windows xp, sp3 and labview 8.6, professional edition. The two computers are in the ethernet network. I'd like to Exchange data between two applications of LV using shared variables. I create a shared variable (published network) on both computers.
  The problem is in the properties of shared variables not possible to bind the variable of the remote computer to the local computer. In the first step, there is even no possible to see any computer on the network. After the registration of the computer (Tools-> shared-> computer registry variable)
  I see the computer remote, but without any variable sharing.

  Do you have any idea how to solve this problem?

  Thank you for the answers.

  Hi ,

  Visit this link, maybe it can help you.

• delay in shared variable writing

  Hi all.

  I use LV 2010 SP 1 on a Windows platform.

  I have a Boolean indicator of façade and a shared Boolean variable that I write to simultaneously. My shared variable is network published with buffering enabled.

  Elsewhere in the same program, I read that the shared Boolean variable *. My problem is that sometimes there seems to be a delay in updating the value of the shared variable. The front panel indicator change, but when I question the common variable must seconds surveys repeated before its value also changes.

  Has anyone else seen this problem? Is there a simple solution?

  Thank you

  Zola

  * Yes, I know I can use the shared variable unique process affecting to communicate within a program, but the shared variable is also used in another monitoring program.

  Check if you write the data at all times and read at the same pace. Since you're using buffer if the receiving party is not fast enough to read the data as your write speed, it may take time to read the data and so it looks like a delay for you. Try turning off the buffer and simply use it as a global variable.

• Shared data varying variable published network write error

  In my project in real time, on the VI host running on my Windows PC, I try to write in a number of published network shared variables.  All these write operations are successful (which means that I can read them on the RT target, then a cRIO-9012), except for these shared variables network-published with data type defined as Variant.  I'm not sure what is causing the problem.

  I take the table of clusters shown here...

  

  .. .and going through one "in Variant' VI and then subsequently in writing to the shared variable (data type: Variant).  Diagnosis of the failure of the VI in real-time to read the data, I found that variable writing shared on the host VI produced the following error:

  Error - 2147467259 appeared to Variable shared in the PC host TTS CTRL.vi

  Possible reasons:

  LabVIEW: Unspecified error (Hex 0x80004005).
  =========================
  System OR Configuration: Various operating default (Hex 0x80004005).

  This error or warning occurred when writing the following shared Variable:
  Shared \\My Computer\Network Variables\TC trust Array Group - network
  Shared \\128.144.90.143\Network Variables\TC trust Array Group - network

  .. where 128.144.90.143 is the IP address of the PC.

  Any thoughts?

  Sean

  I saw this post, and when I found myself with no other option, I have redefined the variables in question to the string data type and replaced all the "to variant" and "given Variant of ' functions with functions 'Flatten channel' and"The string Unflatten"respectively.  Initially, it did not work - functions "Chain Unflatten" would produce error 74, until I realized that the "data includes array or string of size? (T)"input on each 'string Unflatten" function must be set to FALSE. Wiring a constant false for each instance of "Unflatten to the string" seems to have corrected the problem.

  I have still no idea why wouldn t Variant.  Shared variables Editor allows to define a variant data type, so I guess it's supposed to?

  Sean

• Network shared Variable breaks rtexe

  I have a cRIO-9063 which I want to use for the control (PWM digital output for pumps signals) and measurement (temperature and voltage) of a system. In the ideal configuration the cRIO would be able to take measures and rebroadcast to a PC for monitoring and logging. The PC must be also able to change the digital output PWM on the cRIO lines. The cRIO should be able to continue to operate when the PC is not available. To do this, I use Scan interface for data acquisition and shared variables (single editor, no RT FIFO) hosted on the cRIO for network communication.

  I have developed the code for the target cRIO as well as my host PC meets my criteria. However, this code only works in development mode. When I try to build and deploy a rtexe on the cRIO, it does not work. I reinforced to the back and made a simple LED flashing user vi, ensure what I create and deploy properly. Slowly adding things to this flashing vi, I discovered it's shared network variables that break the vi once it is integrated into a rtexe.

  After flipping through other-related posts, I'll include the following:

  -There is no object on the remote VI front panel. Simply add a variable node shared is enough to break the vi (when it is deployed).

  -J' tried including my shared variable library in support of the construction directory, but what I saw there is not copied during construction or deployment. I manually copied the library to the /home/lvuser/natinst/bin/data / directory on the cRIO, then used an invoke node to deploy the cRIO variables when the software starts first. Even when you include a delay of 10 seconds after the invoke node, it did not work, just a mistake of 1043 at "the method or property is not supported in this version of LabVIEW."

  -NSV is referenced as absolute

  Some details of my configuration:

  LabVIEW 2015

  cRIO 15.0

  NOR-RIO 15.0

  Communication via ethernet, static IP

  Any help would be GREATLY appreciated. I suspect that I forget a few minor step or detail, otherwise am poorly understand exactly how and when shared network variables are deployed.

  I found shared to not be worthwhile over the years network variables.

  The RT EXE is not able to use the library to deploy to deploy the shared Variables.  See Help topic: http://zone.ni.com/reference/en-XX/help/371361M-01/lvprop/app_libdeploy_library/

  In general, SV are deployed once the project and they persist through reboots of the RT system.  In general, you should have a startup routine that checks the shared variables and expected for there to be without error on a node of the OAS and then move on to the rest of the program, defining the commissioning of values and check that they spread in the engine of the Variable is a typical method.

  See here for more information on the deployment of a variable in an application of the RT.  http://digital.NI.com/public.nsf/allkb/990508969805A7C086257619007189E7

  The section deployment of Variables shared in a real-time (RT) target running Headlessly is downstairs.  Because you are connected to an HMI PC, you should be able to use the library to deploy feature of the PC code targeting the cRIO.

  Usually, it's a faster, more scalable solution to replace your shared network Variables with a stream of network dedicated to the HMI and another for HMI - RT EXE commands.  You can send complex structures such as a cluster or even define the message as a cluster of enum and variant type to be able to use the Enum to convert the variant correctly according to the Enum value.

• new variable networked shared in my computer, but not in the shared variable engine list

  I have a Variables.lvlib shared on a cRIO target and test algorithms when I don't have access to material cRIO. Thought I could do a new project, add the library to the windows target (workstation). I need to add a few additional variables, I did in the original (i.e., while the library was the target in real time). Then create a new project and added the lvlib to the project (under my computer), and then wrote a VI to write in these SVs. When I let fall a constant Variable Refnum shared on the block diagram and browse for objects variables under 'Variable' Motors > ni.var.psp > localhost > shared Variables, list of variables shows everything except the 6 new variables. When I switch the view 'Current project', I get the same variables for new list WITH THE 6. However if I select the variables in the list and run the VI I get an error-1950679035 impossible to locate the variable in the shared Variable engine. Of course, I forgot something, anyone out there set me straight?

  Thanks for your time - lmd2

  Hello Lawrence,.

  Looks like you'll have to maybe just to deploy the new variables - refer to this document:

  LabVIEW Help: Making static Variables available on a network

  http://zone.NI.com/reference/en-XX/help/371361K-01/lvconcepts/sv_deploying/

  Hope that helps!

• Embedded FPGA vi - network shared variable not updated

  Hello

  I work with an ethernet RIO 9149 of data acquisition. I use a hybrid programming mode.

  I have a very simple FPGA VI that I downloaded on the flash memory. I used the indicator led to show my VI runs once the power of the RIO. Everything is fine, except that my shared network variables are not updated in the DSM ("no known values" displayed). However when I run the FPGA VI of my laptop, only once then stop and close (with 'interactive execution'), then my shared variables are updated in the DSM.

  Any ideas why is this and how do I get the RIO update automatically shared variables without having to run the VI once?

  Thank you very much.

  Hello

  I did a few tests and research and discovered that it doesn't seem to be possible. It is important to note the difference between Network-Published static (NSPV) and Variables of e/s of Network-Published.

  The other are "user defined variable I/O" to communicate between FPGA and RT (RT absent on chassis Ethernet as the NI 9149) host. If these variables are checked to be published-network (in properties). They are accessible by VI running on the hosts of the same LabVIEW project, so you need to run a VI to access, as you mention. This is explained on the next page, Variable IO data custom FPGA of e/s (real-time Module or Module FPGA):

  https://zone.NI.com/reference/en-XX/help/371361H-01/lvioscanhelp/io_vars/#user_IOV

  I did find a way without a host (host RT or Windows PC) running a VI. If you have a cRIO with RT and NPSV host in the RT VI it is possible.

• Are published network shared variable write & read Atomic actions

  Hello

  I have a very basic question about shered (published network) variable.

  I think I know the answer already, but since I couldn't find in my documentation, I thought that it is more prudent to request...

  Are reading and writing on a shared variable of stocks Atomic?

  To be more precise: on my target real time I create an array with data (each element being the configuration item or a cluster containing name, value, and type) and when the table is finished I am this store in a published network shared variable.

  On my host (Windows), I'm voting (in a loop) until the table contains at least 1 item, when this is true I'm parsing all the elements in the table.

  Is there a chance that, reading of the shared variable, the table contains a subset of the original painting on RT target (i.e. the action of reading takes place while writing is still ongoing).

  Or is the action of reading delayed until the write is completed? (i.e. both write and read actions are atomic even over the network)

  I think the latter is true but not could find no evidence in the documentation.

  Kind regards

  SoC

  Hello Rob,

  Yes, you can access the entire value, data type - you use both. For the table data type, the integer value is actually the full picture. So, Yes, you can see reading and writing as Atomic actions.

  But, on the other hand, you can lose data if the RT system rewrites the variable before the host had the time to read. To avoid this, you can enable buffering for the variable. See the following links for more information:

  http://www.NI.com/white-paper/4679/en

  http://zone.NI.com/reference/en-XX/help/371361H-01/lvconcepts/buffering_data/

  Finally, you can also activate a FIFO RT on your target RT if you need to send data through the variable in a deterministic section of the RT. See also, more information:

  http://zone.NI.com/reference/en-XX/help/370622H-01/lvrtconcepts/rt_projectvariable/

• Passing an array via one RT FIFO network shared Variable, Code error-1950679034

  This should be simple.  I'm just passing through a table via a single RT FIFO network shared Variable element.  And yet I get nothing.  How could - not working?  What is this error?

  

  Well... it must have been some sort of thing calendar because adding an expectation of 100 ms fixed it straight up.

  Now don't feel ridiculous

  

• network Publish shared variable

  I'm hosting the OAS of a sbRIO engine, developing with LV10.  I share an array of Boolean values on the sbRIO and I need to be modified by (1) the sbRIO by programming the control array, and (2) a LV GUI running on PC graphically (i.e. option boxes).  I share the table and PC HMI can connect and view the States of the button as established by the sbRIO, but when I try to click on one of the radio buttons, the sbRIO seems to outweigh demand and turn the reverse button (I know demand is through, I see a very rapid change in the State of button/table on a temporary HMI connected through the sbRIO project).

  Do I need a separate shared table for applications for PC/HMI that I must then analyze via w/Combinatorial logic and find the changes then send updates until the sbRIO to write in the "master" control programmatically array?  Or is it a type of feature for arbitration to a shared Variable NP?

  THX

  Hey Atlas,

  This looks like a problem that arises from the conditions of competition, access to shared variables. You always read or write variables in a loop on each application? If the Boolean values are poised to the HMI, you must use a "send" or the "write" button that writes to the shared variable. If the HMI application is constantly reading and writing to the shared variable, you can overwhelm network variable motor and see problems like these. If you still have problems, feel free to post your screws or block diagram screenshots so that we can see what you're doing.

• read into the buffer variable published network shared

  

  I use a shared variable that is published in the network buffer to write data to an RT target and read data buffered by the host application.

  I followed a different behavior regarding data buffering using Variable vs reading read the shared Variable node.

  There is no problem the shared variable node read but using the results of reading variable function of loss of data, such as access without alkaline reserve. I can read only some of my data values.

  I see no difference in access in the buffer in LV2009 help.

  against

  Any help is appreciated

  Christian

  Hi Christian,

  The behavior you describe is because the client side PSP buffering is not applied to the Variable API shared in LabVIEW 2009.  It was a design decision, but eventually, we hope to include this feature in a future version of LabVIEW.  This bug here as you pointed out is the lack of documentation for it.  Corrective Action Request # 202159 has been filed for this issue.

  Let me know if you need assistance working around this issue.

  See you soon,.

• Why network shared variables is wrong values at startup?

  I run the example of the "RT FIFO Variables - Networked.lvproj" expedition. Once I have deploy shared variables that I can run successfully the host and the target live. Data is exchanged as expected. However, once I press the STOP button on the host VI VI target cannot be restarted independently of the execution state of the host VI. The only way I can get the target VI to start running again is to change (for example to add a text box or somekind of NOP) and then redeployed.

  It seems that some incorrect value gets stuck in the target variable stop FIFO and so cannot run the target. I tried to add a variable entry to the variable STOP before the loop in the example, but this is not enough.

  Can someone explain to me why this example of shipping can be run twice consecutively without a necessary redeployment?

  I vaguely remember something on the initialization of the shared Variables (I can't find the reference right now).  But I tried the demo code (finally) on and (as it turns out that) I had reason - is an example of poorly written, precisely because it is 'designed by omission"to work exactly once!

  Remember that instructions must start the host, and then start the target.  The first time, at the start of the target, you get a sinusoid.  But once you stop the host (which also stops the target), if you start again host, then the target, the target will stop immediately.  This is because the target (but not host) the shared Variable stop (when the target starts to run) as True (what it was the previous time the target ran) and stops see.  What you need to do is to provide sufficient time for the Variable (reset) shared between the host and spread throughout the network and gain access to the target.  I tried to put a 50 ms delay before entering the loop of the target - not long enough.  But 500 ms was fine - the example ran fine the second, third and a fourth time.

  I'll bring this to the attention of OR.

  Bob Schor