More shared variable help

Yep, I'm attempting a large shared variable project, so, I guess it's time to get active on the board again.
Anyway, so I had this problem;
http://forums.ni.com/t5/LabVIEW/Getting-a-list-shared-variable-references/td-p/1817829
but we got that figured out.
Now, when I go to write the data to the variables, I can watch it go from 'No Known Value' in the distributed system manager to ' ', and yes, I mean blank. Granted, the data is coming from a simulated DAQ currently, but I can probe the data line in the .vi and there's numbers there, they're just not getting to the shared variable. Any ideas as to what I'm doing wrong? I've got the variables deployed and the shared variable engine is running on the computer. Is there something I need to do programmatically prior to writing to them?
Here's the snippet so you don't have to switch between tabs to look at it,
Thanks for any help,
-Ian
Solved!
Go to Solution.

Hi Ian,
It is hard to tell exactly how the data will display when pulling from a citadel database. One recommendation I have for you is to use the Read Trace/Write Trace .vi's which will allow you to break up the waveform and handle the data apart from the timestamps they are associated with.
Hope this helps!
Allison M.
Applications Engineer
National Instruments
ni.com/support

Similar Messages

Shared Variable Help

Hey,
I need some help with shared variables. Here is what I'm trying to do. I run a vi on the computer that uses a camera to track certain objects. I would like this program to send the position of the object to another vi that is running at the same time on the speedy-33. The speedy-33 takes the position and rotates the robot towards the object. The problem I have is communicating the position from the computer to the speedy-33.
From what I've read, I think I'm supposed to do this with shared variables. On the computer target, I created a library with an integer variable (to hold the x position of the object). I set this variable in the computer vi using the shared variable. All of this is in a while loop. On the speedy-33 VI, I've connected a control to the shared variable. When I run the program everything works as intended so far. When the object's x value changes the control on the speedy-33 front panel changes appropriately. However, when I try to drag the variable onto the speedy-33's block diagram from the project explorer I get a bunch of errors. The first is "My Computer\Variables.lvlib\xpos: Not supported for current target." Since it appears this isn't supported for the speedy-33 how am I supposed to transfer the data?
Hope all that makes sense.
Thanks

Squirell wrote:
Hope all that makes sense.
Well, I for one got lost somewhere in there. Didn't you say that you already had the shared variable in both the computer VI and the Speedy-33?
It may be a good idea to take a look at the Shared Variable Client-Server example, and perhaps test it to see if it, at least, can work on your setup.
I for one gave up on shared variables (flow control was just too much trouble) and am using "functional globals" instead. http://zone.ni.com/devzone/cda/epd/p/id/4364 was particularly helpful.Message Edited by kehander on 02-20-2007 12:46 PM

Using shared variable not in the project.

hi all
I have a project with the 2 RT targets and the development PC which were i currently deploy all my shared variables, But I need to finally deploy these shared variable in a different stand alone windows based machine. To do this I created separate application which does nothing but deploys the shared variables in this PC. but when i tried to bind to this variables (frount panel binding) from my RT targets it woudnt work, the led does not glow, it is always transperent. but when I tried to connect to these variables from my development PC it works fine. I double checked the firewall problem, that is not the case here. Can anyone tell me what am i doing wrong?
Thanx
Arun

Hi Prashanth
Thanks for the reply. I did realize that the front panle connection would not be supported in RT, now i have the shared variables on my RT machine which has te source as the windows machine. If the windows machine is my development machine the shared variables connect fine, but if its a different PC the shared variables connect for few seconds and with the error info "shared variable value 0" then the connection gets disconnected.
Also i read a note in the shared variables help, it said to subscribe and publish on a network shared variable all the shared variable which connects to this variable should be active. does this mean that if there are 2 RT targets that subscribe data and one of them is not switched on the shared variable does not work.?
Thanks again for your support.
Regards
Arun

Why string type shared variable takes more time to update in the client

I am using shared variables to share the data across a master and the client PCs connected in a network. (Network published & no buffering)
I have created an integer type shared variable(I32) and a string type shared variable (data size is 60 bytes) in the Master and subscribing to the same in the client PCs. In the master PC, I am modifying the data in this order - update the data in the string type variable and then update the data in the integer vaiable.
But in the client PCs, due to the size difference in the variables, I am receiving the data of the integer first and after that about 3-4 sec later only I am receiving the string data. Can any optimization be done to reduce this latency period? Instead of the string data type any better data type will reduce this delay?
Please suggst. Advnced thanks.

Latency has a lot to do with your network. 3-4 seconds is a long time though. This could also be due to the larget data size of your string. The integer data size is definitaly not 60 bytes. If you're looking for better performance, I would highly recommend looking into Datasocket communication or TCP/IP communication. (There are shipping example for both.)
When it comes to performance of throughput and efficiency, network-published variables are lower on the totem pole.
I hope this helps,
Kevin S.
Applications Engineer
National Instruments

Need help getting networked shared variables on compact fieldpoint to work

I'm still a newbie and am trying to get Networked Shared Variables to pass from a VI running on a PC to a VI running on a Compact Fieldpoint. I created a VI that sends a message via a Networked Shared Variable and a VI that receives it. I have them both in the same project. If I run them both on the PC, it works, I can send a message string from the first VI to the Networked Shared Variable and read it in the second VI. I have the second VI turn the LED "A" on and the LED "B" off if I send the string "a", and turn the LED "B" on and the LED "A" off if I send the string "b", and turn them both off if I send anything else. It works as expected if both the VIs are running on the PC. The second VI also continuously blinks the LED "C" so I can verify that it's running.
I "deployed" the second VI to the Compact Fieldpoint as follows:
In Project I dragged the VI from My Computer (under Project: name.lvproj) down and put it under the Compact Fieldpoint name.
I right clicked on Compact Fieldpoint name and verified it was set to "Connect".
I right clicked on the second VI and selected "Deploy".
I started both VIs with the "Run" arrow. At this point I know second VI is running since the LED "C" keeps blinking. But, when I try to send an "a" or "b" nothing happens, so the VI on the Compact Fieldpoint must not be receiving the messages in the Networked Shared Variable.
I also right clicked on Compact Fieldpoint name and selected
"Disconnect". The second VI continued to run since the LED "C" keeps
blinking, but I still can't get messages to pass.
Any help will be greatly appreciated.

I got this to work. I moved the library (.lvlib) containing the Networked Shared Variable to down under the Compact Fieldpoint name. Now it works.

Print-time charting with shared variables on a report without groups...

hello all,
I have an interesting conundrum; I am working on a report (Crystal XI) with no groups to it, just several subreports. Presently the report is run weekly and sent to the manager of one of our departments.
The report itself showcases all areas of the department with total tasks, longest outstanding task, average days outstanding, MTD tasks completed, and YTD tasks completed. Due to the variety of tables the data pulls from, I have it set up as subreports that simply display the data.
All total, there are 20 different shared variables that have been obtained from 10 different subreports. I have the shared variables set as the running totals from the subreports (hence, all are print time). Since the running totals and all the subreports are time based and are not actually linked to ANYTHING on the main report, I am struggling with how to set up the formulas described in the white paper, "Charting on Print Time Formulas".
The setting up of the two formulas ({@onchngof} and {@showval}) will be different for my situation, as all of the subreports run off of date information relative to when the report is ran. I've got all of the subreports that the shared variables originate in early in the report; but where to from here?
Would I set up maybe a date grouping or some other non-essential consistent grouping to make it work? The way this report is, it really doesn't need grouping, because the main report is just a display agent for the subreports...
As always, any help is greatly appreciated!

Let me ask couple of questions before trying to resolve this.
1. The chart you are trying to built is placed in which section and is it on Main report or sub-report of its own. This is needed because if you are trying to access shared variables values in Main report, the section should be below the sub-report placed sections.
2. Try pacing few test formulas in Main report and make sure the correct values are being pulled in on Main report.
If you are successfully pulling the variable values on the report, try creating a simple chart in report footer with the values you have pulled and see if its taking you somewhere...
Would need more information on how those variables are being accessed form sub to main or sub to other sub for example are you making an array of those variables and splitting or bringing it in as separate...

How to add a new Shared Variable programmatically to an existing and deployed library?

Hi there!
I am trying to accomplish this on both LabVIEW 8.6 and LabVIEW 2010 and seems like it's not any different in this situation.
My case: A project has a library with 4 Shared Variables (SVs). The library and the variables are deployed (visible in Distributed System Manager 8.6/2010). I want to add 2 more variables into this library. It is possible to do this manually from Project Explorer window's options menu. But while running an application it has to be done programmatically. Can I provide the library reference to the one currently existing without creating a new one?
"Create Or Add Library To Project" function in the Datalogging and Supervisory Control (DSC) toolkit does not help in this case. That function, as the name suggests, just tries to create a new library in the project.
Two possible methods:
The function "Add Shared Variable To Library" (DSC>EngineControl>Libraries & Processes) needs a library reference, which could be provided via "CreateOrAddLibraryToProject" function, but this function tries to create a new library, and if I provide the path of the existing library it throws an exception that the library already exists in the project (yes, as I wrote above, I need to add new variables to an existing and deployed library).
OR
The function "Create Shared Variable" (DSC>EngineControl>Variables & I/O Servers) will add Shared Variable in a process, and not physically in a library file, and the problem (limitation) with this approach is that it doesn't allow to add complex data type Shared Variables (for example in LabVIEW 8.6 it has only 4 datatype options in input parameter, and even in LV2010 it does not have "Image" datatype that I need).
The scond method is my preferred method as it allows to work on Online Shared Variables and doesn't create them physically in libraries (and this is good as the variables' scope remains only till the Variable Engine is running). But it doesn't support advanced data types, and the first method is powerful in terms that it supports to virtually any datatype, it just seems tricky to get that reference to the library.
Any tips?
Thanks ahead!
Vaibhav

<<<<>>>>
As the above two images show, while a library does not exist, it is easy to use the "CreateOrAddLibraryToProject.vi" which will add a new library to the project (if it doesn't exist on file system, a new library will be created) and that way, using the reference (the green wire going out from the function and the Case Structure, can be used to add Shared Variables to the library. The problem was what to do when a library already exists in the project, how to add more variables to it. I was looking for a way to get a library reference, and somehow I could not see it inside a Project's property (VI Server functions). Hence I posted the question. And upon continuing my search, I found it on the Application's property list.
I hope it was useful for someone else as well. And thanks for the replies. Please share a better idea if you have.
Vaibhav

Peculiar behavior of Shared Variable RT FIFO

I'm trying to "leverage" the enhanced TCP/IP and Shared Variable properties of LabView 8.5. My application involves (among other things) doing continuous sampling (16 channels, 1KHz/channel) using 6-year-old PXIs (Pentium III) and streaming data to the host. I developed a small test routine that was more than capable of handling this data rate, even when I had the host put a 20msec wait between attending to the PXI (to simulate other processing on the host). To do this, I enabled the "RT FIFO" property of the Shared Variable (which was an array of 16 I16 integers) and specified a buffer size of 50 (that's 50 arrays). Key to making this work was figuring out the "error codes" associated with the SV RT FIFO, particularly the one that says the FIFO is empty (so don't save the "non-data" that is present).
Flush with success, I started developing a more realistic routine that involves rather more traffic between Host and Remote, including the passing back and forth of "event" data. These include, among other things, "state variables" to enable both host and remote to run state machines that stay "in sync"; in addition, the PXI also acquires digital data (button pushes, etc.) which are other "events" to be sent to the Host and streamed to disk. I developed the dual state-machine model without including the "analog data" machine, just to get the design of the Host/Remote system down and deal with exchanging digital data through other Shared Variables. Along the way, I decided to make these also use an RT FIFO, as I didn't want to "miss" any data. One problem I had noticed when using Shared Variables is the difficulty of telling "is this new?", i.e. is the variable present one that has been already read (and processed) or something that needs processing. I ended up adopting something of a kludge for the events by including an incrementing "event ID" that could be tested to see if it was "new".
Today, I put the two routines together by adding the "generate 16-channels of integer data at 1 KHz and send it to the Host via the Shared Variable" code to my existing Host/Remote state machine. I used exactly the same logic I'd previously employed to monitor the RT FIFO associated with this Shared Variable (basically, the Host reads the SV, then looks at the error code -- a value of -2220 means "Shared Variable FIFO Read Buffer Empty", so the value you just read is an "old" value, so throw it away). Very sad -- my code threw EVERYTHING away! No matter how slowly the Host ran, the indicator always said that the Shared Variable FIFO Read Buffer was empty! This wasn't true -- if I ignored the flag, and saved anyway, I saw reasonable-looking data (I was generating a sinusoid, and I saw numbers going up and down). The trouble was that I read many more points than were actually generated, since I read the same values multiple times!
Looking at the code, the error line coming into the Shared Variable (before it was read) was -2220, and it remained so after it was read. How could this be? One possibility is that my other Shared Variables were mucking up the error line, but I would have thought that the SV Engine handling reading my "analog data" SV would have set the error line appropriately for my variable. On a hunch, I turned of the RT FIFO on the two Event shared variables, and wouldn't you know, this more-or-less fixed it!
But why? What is the point of having a shared variable "attached" to an error line and having it return "Shared Variable FIFO Read Buffer Empty" if it doesn't apply to its own Read Buffer? This seems to me to be a very serious bug that renders this extremely useful feature almost worthless (certainly mega-frustrating). The beauty of the new Shared Variable structure and the new code in Version 8.5 is that it does seem to allow better and faster communication in real-time using TCP/IP, so we can devote the PXI to "real-time" chores (data acquisition, perhaps stimulus generation) and let the PC handle data streaming, displays, controls, etc.
Has anyone been successful in developing a data-streaming application using shared variables between a PXI and and PC, particularly one with multiple real-time streams (such as mine, where I have an analog stream from the PXI at 16 * 1KHz, a digital stream from the PXI at irregular intervalus, but possibly up to 300 Hz, and "control" information going between PC and PXI to keep them in step)? Note that I'm attempting to "modernize" some Version 7 code that (in the absence of a good communication mechanism) is something of a nightmare, with data being kept in PXI memory, written on occasion to the PXI hard drive (!), and then eventually being written up to the PC; in addition, because the data "stayed" on the PXI, we split the signal and ran a second A/D board in the PC just so we could "see" the signal and create a display. How much better to get the PXI to send the data to the PC, which can sock it away and take samples from the data stream to display as they fly by on their way to the hard drive!
But I need to get Shared Variables (or something similar) working more "understandably" first ...
Bob Schor

Bob,
The error lines passed into and out of functions are just just clusters with a status boolean, an error code, and an error string, and are not "attached" to a particular function as you describe in your post. Most functions have an error in input and an error out output, and most functions will simply do nothing except pass through the error cluster if the error in status is True (to verify this for yourself, double click on a function such as a DAQmx Read or Write and look at the block diagram. If there is an error passed in, no read/write occurs). This helps prevent unwanted code from executing when an error does arise in your program. By wiring the error cluster from your other shared variables to your analog data variable, you're essentially telling LabVIEW that these functions are related and that your analog data variable depends requires that the other shared variables are functioning properly. The error wire is a great way to enforce the flow of your program, but you must always consider how it will affect other functions if an error does arise.
Anyways, it's great that you have things more or less working at the moment. Keep us all updated!

CRIO and ni 9234 modules not working or communicating through fpga with accelerometers, fpga connected to real time application which is also connected to shared variables linked to modbus slave

Hi,
I have a compact rio which has a 4 way chassis attached to that chassis is three ni9234 modules they are linked using fpga to a real time application then using shared variables in the low speed loop that are linked to a modbus slave to communicate with dcs, the ni 9234's have accelerometers connected to them with iepe ac coupled option on the c modules, my problem is the real time application seems to be running okay even when power loss occurs it restarts with no problem and the fpga writes to the portable hard drive bin files fine but without a accelerometer connected I get low noise readings as soon as I connect a accelerometer to any one of the 10 outputs it just goes to a fixed number (0.03125) as soon as disconnect it again it reverts back to reading noise, I have run a scan on the modules and only get a spike when I connect or disconnect the accelerometer, I have tested the voltage at the pins of the module and I get 22 volts dc which makes it more likely that the hardware is not the problem but a software is maybe causing this to hang-up, I attach project and files for your perusal. I also carried out a new project which in scan mode directly linked the module input to shared variable and the same scenerio again. Help would be much appretiated.
Many thanks
Jason
Solved!
Go to Solution.
Attachments:
logger 2plusmodbus2.zip ‏679 KB

Whren using waveform acquisition with the 9234s we recommend the following FPGA and RT template.
http://sine.ni.com/nips/cds/view/p/lang/en/nid/209114
it can be extended as a data logger with:
http://zone.ni.com/devzone/cda/epd/p/id/6388
or using shared variables combined with scan engine
http://zone.ni.com/devzone/cda/tut/p/id/9851
The FPGA in all of these, as well as the RT framework have been used successfully by 1000s of users. I would recommend giving these a try.
Preston Johnson
Principal Sales Engineer
Condition Monitoring Systems
Vibration Analyst III - www.vibinst.org, www.mobiusinstitute.com
National Instruments
[email protected]
www.ni.com/mcm
www.ni.com/soundandvibration
www.ni.com/biganalogdata
512-683-5444

DSC: Importing Shared Variables results in error -1950679010

This post is more of an "FYI" rather than a question. I am using LV DSC 8.2.
ASIDE: I ran into this problem because I was trying to solve a related problem with Deploy Library.vi (I had dependant libraries that deployed manually, but not programmatically). Eventually, I found the answer in http://digital.ni.com/public.nsf/allkb/8EF71E1DDDC36C908625716900594B50 (not a very satisfactory answer however, IMHO).
During my solution search, another hint was provided with http://forums.ni.com/ni/board/message?board.id=170&message.id=177268&requireLogin=False which hints that using a "Network" defined SV, as opposed to a "Project" defined SV, could help. Then I discovered the difference between NetworkrojectPath and Network:URL in the SV property definition. Then I realized that NetworkrojectBinding is exposed in the Import fields (using the Multiple Variable Editor to do the importing of course), and this gave me the idea of being able to define a Network SV using the Import function.
Unfortunately, it does not work. In the csv file I set NetworkrojectBinding to FALSE, Network:UseBinding to TRUE and provide a valid Network SV path, but this results in error -1950679010: "Shared variable is bound but path or URL is not specified", which occurs when trying to save the LVLIB. It would be nice to know why this doesn't work, as I think it should. I think it is a problem with the SV import mechanism.
David Moerman
TruView Technology Integration Ltd.

Yes, you can do this programatically. I've attached a small chunk of example code (LV 8.5) that creates just 1 variable, as well as an image of it in case you are using an earlier version of LV. If you want to create multiple variables for the same library just put the "AddSharedVariableToLibrary" in a loop, of course.
David Moerman
Attachments:
Create Library and SV.PNG ‏48 KB
Create Library of SVs - BASIC.vi ‏24 KB

LV7.1 DSC tag engine VS LV8.6 DSC shared variables

I'm currently running LV7.1 with DSC and RT. To handle communications and logging RT variables I'm using the init / read / write publish.vi's on the RT side and datasockets on the HMI side (Windows XP). This has worked out great - new tags can be programmatically created in real time with the publsih vi's and then I go to the the .scf file and use the tag configuration wizard to add them to my scf file and handle data logging. This worked very well - the wizard would organize all of the memory tags into folders by block name used by the init publish vi. I could also select entire groups of tags and add hundreds at a time to the .scf file. Hardware Tag also worked in a similar fashion, organizing tags by controller and module folders. Now - looking at LV8.6.I found I can still use the init / read / publish vi's on the RT side - great. However there is not tag configuration editor as in LV7.1 to let me add large numbers of tags through a wizard. The closest thing I've found is to create a library to represent each block name from the RT init publish.vi then use "create bound variables" option under the library to bind the new shared variables to the RT memory tags. I can browse to the tags on the controller by network items, but when I add them it doesn't bring the block name of the tag as it did in 7.1, only the item name. I use a lot of PID loops that share the same tag names (i.e.: P,I,D, mode, output), so not including the block name represents an organizational problem. The problem with this is, it's very labor intensive compared to the wizard in LV7.1 DSC, especially talking about creating systems with thousands of RT memory tags. Also, there is a similar problem with hardware channels (I'm using compact FieldPoint). To log channels via DSC do I have to create a shared variable for each channel to access the DSC logging capabilities? Again how do I add all of the hardware channels in some organized fashion? I hope I'm missing some tool that is an analog to the tag configuration wizard to bring in these channels and organize them. Any help or suggestions would be appreciated. Thanks,Brad

Hi lb,
We're glad to hear you're upgrading, but because there was a fundamental change in architecture since version 7.1, there will likely be some portions that require a rewrite.
The RTE needs to match the version of DSC your using. Also, the tag architecture used in 7.1 is not compatible with the shared variable approach used in 2012. Please see the KnowledgeBase article Do I Need to Upgrade My DSC Runtime Version After Upgrading the LabVIEW DSC Module?
You will also need to convert from tags to shared variables. The change from tags to shared variables took place in the transition to LabVIEW 8. The KnowledgeBase Migrating from LabVIEW DSC 7.1 to 8.0 gives the process for changing from tags to shared variables.
Hope this gets you headed in the right direction. Let us know if you have more questions.
Thanks,
Dave C.
Applications Engineer
National Instruments

Migrating large project from DSC 7.1 to LabView 2009 Shared Variables ... What's the next step after recreating my variables?

I am in the process of migrating a large distributed (multi-workstation) automation system from the LabVIEW 7.11 DSCEngine on Windows XP to the LabVIEW 2009 Shared Variable Engine on Windows 7.
I have about 600 tags which represent data or IO states in a series of Opto22 instruments, accessible via their OptoOPCServer. There are another 150 memory tags which are used so the multiple workstations can trade requests and status information to coordinate motion and process sequencing. Only one workstation may be allowed to run the Opto22 server, because otherwise the Opto22 instruments are overwhelmed by the multiple communications requests; for simplicity, I'll refer to that workstation as the Opto22 gateway.
The LabVIEW 2009 migration tool was unable to properly migrate the Opto22 tags, but with some help from NI support (thank you, Jared!) and many days of pointing and clicking, I have successfully created a bound shared-variable library connecting to all the necessary data and IO. I've also created shared variables corresponding to the memory tags. All the variables have been deployed.
So far, so good. After much fighting with Windows 7 network location settings, I can open the Distributed System Manager on a second W7/LV2009 machine (I'll refer to it as the "remote" machine henceforth) and see the processes and all those variables on the Opto22 gateway workstation. I've also created a few variables on the remote workstation and confirmed that I can see them from the gateway workstation.
Now I need to be able to use (both read and write) the variables in VIs running on the remote workstation machine. (And by extension, on more remote workstations as I do the upgrade/migration).
I have succeeded in reading and writing them by creating a tag reader pointed at the URL for the process on the Opto22 gateway. I can see a way I could replace the old DSC tag reads and writes in my applications using this technique, but is this the right way to do this? Is this actually using the Shared Variable Engine, or is it actually using the DataSocket? I know for a fact that attempting to manipulate ~800 items via Datasocket will bog down the systems.
I had the impression that I should be able to create shared variables in my project on the remote workstation that link to those on the Opto22 gateway workstation. When, however, I try to browse to find the processes on that workstation, I get an error saying that isn't possible.
Am I on the right track with the tag reader? If not, is there some basic step I'm missing in trying to access the shared variables I created on the gateway workstation?
Any advice will be greatly appreciated.
Kevin
Kevin Roche
Advisory Engineer/Scientist
Spintronics and Magnetoelectronics group
IBM Research Almaden

I have found the answer to part of my question -- an relatively easy way to create a "remote" library of shared variables that connect to the master library on my gateway workstation.
Export the variables from the master library as a csv file and copy that to the remote machine.
Open the file on the remote machine (in excel or the spreadsheet app of your choice) and (for safety's sake) immediately save it with a name marking it as the remote version.
Find the network path column (it was "U" in my file).
replace the path for each variable (which will be either a long file path or a blank, depending on the kind of variable) with \\machine\'process name'\variable name
where machine is the name or ip address of the master (gateway) workstation (I used the ip address to make sure it uses my dedicated automation ethernet network rather than our building-wide network)
and process name is the name of the process with the deployed variables visible in the Distributed System Manager on the gateway machine.
NOTE the single quotes around the process name; they are required.
The variable name is in the first ("A") column, so in Excel, I could do this for line 2 with the formula =CONCATENATE("\\machine\'process name'\",A2)
Once the formula worked on line 2, I could copy it into all the other lines.
Save the CSV file.
Import the CSV into the remote library to create the variables.
Note: at this point, if you attempt to deploy the variables, it will fail. The aliases are not quite set properly yet.
Open the properties for the first imported variable.
There is probably an error message at the bottom saying the alias is invalid.
In the alias section, you'll see it is set to "Project Variable" with the network path from step 4.
Change the setting to "PSP URL" with the same path and the error message should disappear.
Close the properties box, save the library, and then export the variables to a new CSV file.
Open the new CSV file in Excel, and scroll sideways to the NetworkrojectBound field.
You'll notice it is False for the first variable, and true for the rest. Set the field FALSE for all lines in the spreadsheet.
Scroll sideways... you'll notice there are two new columns between NetworkrojectPath and Network:UseBinding
The first one is NetworkingleWriter; it should already be FALSE for all lines.
The second one is Network:URL. That needs to be set equal to the value for each line of NetworkrojectPath.
You can accomplish this with a formula like in step 4. In Excel it was =U2 for line 2, and then cut and paste into all lines below it.
There is a third new field, Path, which should already be set to the location of the variable library. You don't need to do anything with it.
Save the edited CSV file.
Go back to the remote library, and import variables from the just-edited remote library CSV file.
Once you have imported them and the Multiple Variable Editor opens, click on done.
You should now be able to deploy the remote variable library without error. (Make sure to open the Distributed System Manager and start the local variable engine. It took me a few failures before I realized I had to do that before attempting a deployment).
Voila! You now have a "remote" library of shared variables that references all the shared variables on the master machine, and which should be deployable on other machines with very little difficulty.
It actually took longer to write out the process here than to perform these steps once I figured it out.
Kevin Roche
Advisory Engineer/Scientist
Spintronics and Magnetoelectronics group
IBM Research Almaden

Deploying Shared Variables to Remote Target?

I have a 2-application server/client setup where my client(s) merely read information "published" by the server via a Network-Shared Shared Variable. If I run my server on a "clean machine" (i.e. no LabVIEW development) and I "publish" the shared variable library (via the "Library : Deploy Library" Application method) to the localhost, I have no problems whatsoever reading the data in the client (the path of the .lvlib file provided to the Invoke Method VI is an absolute path to the .lvlib file, BTW). However, I'm having a bear of a time getting the server to deploy the library to a machine running a second client on the same network - to do this I still use the same absolute path to my .lvlib file for the first input to the method (it's in the same place on the target as well as on the host, not that I know what this means for a targeted host) and I specify the IP Address of the target machine on the second input. There is no firewall on either machine (I removed it because I was getting nowhere and needed to eliminate a possible source of problems) and my router doesn't filter traffic going across the local subnet. Am I not using the programmatic publishing correctly to publish to another target (from within the server), or can anyone point out any problems in my usage?
By the way, if I publish to the local host (127.0.0.1 or the host machine's IP address) I do not get an error out of the "Invoke Node" VI. However, when I try to publish to a network target (both machines have the Variable Manager running and both machines work fine if both server and client are on the same machine) I get error code 1 and the message: "Invoke Node in MyServer.vi<APPEND> Method Name: <b>Library : Deploy Library</b>" which is anything but helpful.
Any help would be greatly appreciated!
-Danny

Hi Arun,
I hope you're doing well. I'd like to clarify the architecture that you are actually using. It sounds like you are deploying a network-published shared variable library on two seperate host PCs. You are then attempting to read data from both of these hosts from a RT target using the Datasocket VIs. The RT target seems to be reading from the shared variables from one of the hosts just fine, but you can't read from the other host. Are both hosts deploying their libraries in an executable as mentioned in previous posts, or is the deployment process done through the LabVIEW development system? Also, when you connect to the hosts using Datasocket, how are you entering in the addresses for each item? Lastly, it might help to know whether you have LabVIEW and LabVIEW Real-Time versions 8.0 or 8.0.1. If you could provide some more information on your set up, we can try to give some suggestions. Thanks!
Thaison V
Applications Engineer
National Instruments

Target VI stops before being commanded using shared variable

All,
I decided to post this in general since it deals mostly with shared variables however I am working with a RT target so feel free to move it to another forum.
I originally posted a problem I was having with the RT Module Getting Started example, regarding the 1950679023 error, and trouble shooting led me to create the simplest test project I could think of. (I know you all want a link to the VIs but my company does not allow me to access internet file sharing sites to upload data so bare with me.)
NOTE: This is NOT an RT project. Just deployed on an RT target.
In Project Explorer I have Host.vi under " My Computer " and Target.VI and 3 networked-published shared variables (call them A,B,C here for simplicity) with RT-FIFO checked, under my RT target.
Host.vi is a single while loop with a 0.5sec time delay express VI. The loop contains (along w/ the time delay) 1 numeric control wired to SV A, 1 numeric indicator wired to SV B, and finally a Stop button wired to SV C plus the conditional term (stop if True). SV A is configured as write, SV B as read, and SV C as write.
Target.vi is a single while loop with a 0.5sec time delay express VI. The loop contains (along w/ the time delay) a numeric add function wired to a constant double and SV A configured as read. Also, SV C is wired to the conditional term configured as read (stop if True). The VI adds the two numbers, one of which is controlled by the Host.vi using SV A, and sends the results to Host.vi using SV B until the Stop button is pressed on Host.vi and sent back to Target.vi using SV C.
I successfully ran this project (which included my always present 1950679023 error). Then changing no code but merely redeploying/running it again right after or through out the course of many other project deployments I get incorrect data on Host.vi. Basically sometimes it would work, sometimes it wouldn't; having changed NO code. First discovery was that Target.vi would automatically stop after running ~ 1sec since deploying/running on the target and before I could disconnect and open/run Host.vi. I then deployed/ran Target.vi with a probe on the wire between SV C and the conditional term and highlight execution running. After an average of 3 runs through the loop the SV C would automatically send out a True signal even though I never open/run Host.vi. How can shared variable C, which is write controlled by Host.vi, automatically change it's state like that when I never even open/run Host.vi?
Another interesting observation is, If I first open/run Host.vi and then deploy/run Target.vi, the program ALWAYS works. But those steps go against my limit understanding of running VIs with shared variables on a target, which I got from NI's RT Module Getting Started Guide? I am going to have a hard time developing anything useful with these shared variables if I can not get the LV RT Guide example and this simple VI working. Any help would be great.
Thanks
JD
P.S. I've noticed this error message a few times during deploying/running either the Host.vi or Target.vi. The error is not consistent; sometimes I see sometimes I don;t.:
error-2147220727 (Hex 0x80040309)
The client process cannot communicate with the configuration server process. If this problem persists please note the steps you performed that led to this error and contact technical support.
PXI-1045,PXI-8196 RT,PXI-4220 (slot 2),(2) PXI-6259 (slot 3 and 4),PXI-5152 (slot 5),PXI-2585 (slot 6),PXI-5404 (slot 7)
LV 8.2.1, RT 8.2, DAQmx 8.5, MAX 4.2, VISA 4.1,
Pharlap OS ver.12.0, PH_EXEC ver. 8.2

Thanks for the responses, (sorry this is going to be long)
- First question is how do you initialize a shared variable (SV)? I don't have the DSC module, which I know has an initial value parameter. The SV is configured as a read and doesn't have any inputs, so am I missing something on the way to initialize it? I know the boolean defaults to False, which is good for my application. Also, right clicking on the SV doesn't bring up any obvious solution? Help if I am lost. Also, all my code is inside the loop (both the RT.vi and Host.vi), nothing is outside the loop.
- I think I learned something through some trial and error. I made this test VI project even simpler by just having an incremental counter using shift registers inside the RT.vi while loop. The results of that counter are sent out, by way of a network-published SV, to the Host.vi. This network-published SV is located under the target within the Project Explorer. I temporarily got rid of the boolean SV, which was used to stop both the RT.vi and Host.vi. It was that boolean SV that gave me all the problems.
This new test VI works consistently (also as a stand alone application, which was a first for me). My thoughts are that the issues had something to do with not "completely" removing all previous run instances of the VI and associated SVs/library from the RTs memory. I think I was getting old buffer data or SV corruption when, on my first test VI, would re-run the RT.vi and have the boolean SV inexplicitly switch states from False to True, even though the write controlled instance on Host.vi wasn't even running. I now undeploy everything (and check the Variable Manager) to make sure I have a clean sheet when re-running the VI. Now that brings up a question, is undeploying the only, or proper, way to clear the RT's memory?
Anywho, I reintroduced the boolean SV into this new edition of the test project (read instance on RT.vi and write instance on Host.vi, while "hosted?" under the target in the Project Explorer) and everything works (although I still get that 1950679023 error once in a while when running for the first time). Meaning, I deploy the RT.vi then disconnect, then run the Host.vi and get valid data, then I press stop and both VI's stop. I then clear out the RT memory (I think all of it?) using undeploy and then repeat. Doing this I get consistent, valid results. If this seems like a learning experience for me please let me know, I don't want something to "work" just by accident.
- To answer the second reply: 1) all the SVs where created under the target in the Project Explorer. Also, I have not unchecked auto-deploy or tried deploying manually, but will give it a try. That brings up a great point, most of NI's data on SVs is "technical specification" like and not very in depth for something so complex. I have not been able to find any "tips/tricks" or "best practices", like trying to deploy manually. Is it because SVs are still new?? Also, a frustrating thing is that NI's step by step tutorials treat SVs like they are simple and fool proof, but following their instructions to the T I get errors. They leave out all the little nuances of correctly working with SVs and so it creates a steeper learning curve. Enough of my rant.
Thanks again for the responses and any more help to come.
JD
PXI-1045,PXI-8196 RT,PXI-4220 (slot 2),(2) PXI-6259 (slot 3 and 4),PXI-5152 (slot 5),PXI-2585 (slot 6),PXI-5404 (slot 7)
LV 8.2.1, RT 8.2, DAQmx 8.5, MAX 4.2, VISA 4.1,
Pharlap OS ver.12.0, PH_EXEC ver. 8.2

Modbus ip shared variable network failure

I am using lab view 8.6 DSC module to communicate to a watlow system which contains five watlow 96 controllers and an EM gateway. I have created shared variables for the process temperatures and setpoints for each of the five controllers using watlow modbus register Numbers with a 400001 offset. I have also created shared variables for Updating,CommFail,UpdateNow,and UpdateRate which where predefined. I have error when starting the VI if the SV has been dragged and dropped into the block diagram. The message is Error -1967353902 (The Modbus I/O server failed to receive any response from the Modbus slave device.) occurred at SV in vi. If I bind a variable in the VI to this same SV the error does not occur but the variable cycles between Good, Network Failure, No known value, and device failure as stated in the variable manager watched variables. The Updating, CommFail and UpdateRate all have a consistent Good in the quality column of the variable manager. UpdateNow has X in value, type, timestamp, and quality columns. CommFail and Updating does cycle between true and false randomly. I have tried a third party software called SpecView 32 demo to see if the commincation with the modbus system is not working and I can create five watlow controlers on my screen and direct them to the ip address along with a unit address and the system works without faults. This leads me to believe the commincation bewteen the SV Engine and the IP address is not correct. HELP Please.
Robert Jensen
UND EERC

If your application can deal with it I would recommend staying clear of the 'Networked Published' option.
When I started my Modbus development on cRIO....I left it enabled, and with ~100 shared variables on a 9074, the CPU was railing, and I saw a buffering behavior on the shared variables (which was not desirable in my application).
In my application I am using the old modbus library (as apposed to the new API) for cRIO to slave comms, the cRIO being the master.
I am also using the IOserver making the cRIO a slave to an external SCADA - and it passes essentially the same data arrays as I use on the modbus library for my local HMI [Not an NI product].....Which is two full Modbus frame writes (@ 120 words each, and about 60 words more for ~300 words outbound from the cRIO).
The IOserver slave was a recent addition and did not add much to the CPU load - although only 16 bytes is high speed, the balance of the total word package is at either 1 second or 3 seconds.
So, in my experince, the 'Networked Published' option adds significant CPU loading (on entery level cRIOs) YMMV.
I am huge fan of the shared variable engine (some at NI were pusing the CVT, and TCE etc...). However most of my shared variables are not the Networked Published variety (excepting local module channels) those have remained networked published for DSM (Distributed System Manager) use.

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