Replace local shared variables

Hi,
I have a bunch of VIs in PXI RT target. There are about 300+ local shared variables distributed among these VIs. What I'd like to do is to change all these VIs target to PC instead of RT and debug and test these VIs logic in my PC. The reason that sometimes I could not use RT target for debugging purpose is because it is used to test the other program. The problem I have is that my local shared variables library is set up under RT target, how could I transfer the shared variable library to my PC. Even there is a way to transfer the library to my PC, It is hard to monitor and change the value of these local shared variables. I am thinking setting up a global variable VI in my PC and replace all these local shared variables with global variables. In that case, it is easy for me to control and read the variable value from global variable VI. My question is whether there is an easy way or tool to replace these local shared variables with global varaibles, and after I finish debugging VIs in my PC I could replace them back.
Jason

Hi,
All of the files you deploy to your RT system are stored on your host PC. If you want to run some of the VIs on the host PC instead of the RT target, all you should have to do is move them to your PC in your project or create a new project and add the files and libraries you want to use. If you want an easy way to monitor the values of shared variables you can use the shared variable manager available under the tools menu in LabVIEW. Unfortunately there is not a utility to convert local shared variables to global shared variables.
Eric A.
National Instruments
Distributed I/O Product Support Engineer

Similar Messages

LabVIEW 8.0 Run-Time engine & shared variables

Has LabVIEW 8.0 Run-Time Engine the shared variable's support, I wonder?
The thing is that .exe with globals/locals runs alright, but beeing replaced with shared variables it refuses to run.
What's wrong? May be need in library(s) absend?
Thanks.

You can use the Shared Variable in the Run-Time Engine (you do not need DSC).
Can you be more specific about what happens when it refuses to run? Are you seeing an error message?
If you are using Network-Published shared variables, they need to be deployed before you run the application. You can either deploy them manually with the project, or your application can programmatically deploy them. You can find some more information about this in the LabVIEW Help under "Shared Variables and Stand-Alone Applications or Shared Libraries" (follow this link and scroll down to the bottom):
http://zone.ni.com/reference/en-XX/help/371361A-01/lvconcepts/project_variables/
-Chris

Shared variables problem

I have 2 applications runnng in different PC connected to the same network
Both applications are for testing purposes before going on with the real implementation. Written in LV 8.5 and based on Shared Variables.
While everything is fine when those application run on the same PC (in effect, localsystem), nothing seems to work when each is active in the proper PC.
Shared variables seem not to be seen from outside the PCs.
This happens also when I use Variable manager on both machines: I create a variable on PC1, defining it as published. Then I create another variable on the other machine (PC2) and try to bind it to the variable deifned in the PC1. Pressing the Browse button the list of PCs networked to mine appears. Selecting th eone I need (PC1), Variable Manager tries to populate the tree but hangs up. Or, better said, simply does not populate the tree. The ariable Manager still works but the item son the other PC are not seen.
Any suggestion?
Regards
Walter

Hi there,
I'm having a very similar issue. My set up is 2 pc's on the same network, the "server" (date generated on this pc) running LV 8.0 ip#1, the other is running LV 2010 and will only see the data, ip#2.
I have set up two test network shared variables and configured them on the server machine Ip#1 to bind to ip#2. When I run the vi's I see that the shared variables are deployed to the particular machine.
On ip#1 I included a test vi in the project to read data from the ip#1 shared variable, and I see no data. I have other local shared variables working within ip#1, but the network shared variables cannot be read even within the same project.
Any ideas as to why I cannot read the networked shared variable within the same project on the same computer?
Also the link about multiple network-adaptors is dead. I have seen strange issues when configuring the networkd shared variables if I have a VPN sessing going to an outside network on both computers, I will see both the windows computer name and the ip address.
Is there anyway to delete a computer after adding it as a shared variable potential source?
Thanks for any help, there are a couple of questions here.
Jim

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

Shared variables update in QuickClient but not in Variable Manager

Greetings,
I am using LV 8.6 Developer with the DSC module installed. Also, I'm using WinXP Service Pack 3.
I am trying to create a VI that will interact with an OPC server connected to some equipment.
I've created shared variables to read the value of tags in my OPC server exactly according to the instructions on this page:
http://zone.ni.com/devzone/cda/tut/p/id/6346
For some reason though, the value of the shared value never updates to reflect the value on the server.
When I follow the tag on the OPC QuickClient, it updates just fine, but somehow the value of the shared variable isn't updating.
I also tried retreiving this data using the DataSocket method in the "Multiple OPC Items Monitor.vi" example, but running that VI crashes LabView every time.
Also, I can create a shared variable and write to tags using a VI, but I can't read them.
It seems like I'm *this* close to getting the shared variables to work. Any suggestions?

Hi Rob,
To answer your questions...
DataSocket: NI doesn't give me the option to investigate the error when I restart the program. I did a search for .cpp files, but none turned up. I did collect the error report that Windows generates, and I attached it. I'm not sure if that would be something useful or not.
SharedVariables: I went to use the Distributed System Manager to take a look at the variables. For both my shared variable as well as the tags on the I/O data source, the data type is listed as "advanced" and the quality is "unknown bad." I collected the logs from the I/O server and attached them. Oddly, when I look through there, I see some Quality=BAD and some VT_ILLEGAL flags. The deadband is set to zero, and the update rate is 1,000ms.
Also, I've configured the DCOM and Local Security Policy settings as described in numerous support articles, and my Windows Firewall is turned off. The OPC server and LabView reside on the same computer.
I suppose the confusing thing is why the QuickClient works fine, but the SVE doesn't.
I've tried this on three different computers with the same results in all cases. Currently, LV and the OPC server is the only software installed on any machine. The only other OPC server I have access to is the LV server, and it seems to work okay.
Thanks,
Wes
Attachments:
a793_appcompat.txt ‏133 KB
screen.JPG ‏105 KB
OPC I-O Server Diagnostic Information.txt ‏69 KB

Dsc opc shared variables yields Server Failure

I've been struggling with the transition from DSC 7.1 to 8+ ever since the release of version 8. I use the Allen Bradley OPC server supplied with the DSC module (Industrial Automation OPC Servers v 5.1) to communicate with a PLC 5/30 via Ethernet, or at least I did when I was using 7.1.
Prior to today I always failed to get the shared variables that were bound to addresses in the OPC server to deploy, usually getting an error number that started with -19. However today I finally got it to deploy by keeping the I/O server and the shared variables in separate libraries within my project. Now that they deploy I find that I am unable to monitor them. I keep getting a Server Failure. I have browsed the forums here heavily, and the documentation all relates to remote OPC, which is not what I'm doing here (OPC client and server are on the same machine). I tried changing the login account for the Variable Engine service anyway, but that doesn't help, so I put it back.
I have had some luck simply binding my front panel objects to the OPC server addresses using Datasockets, so it appears that my OPC server is working. However, Datasockets is not a viable option for me because there are times when my project needs to write to a large number of addresses in the PLC sequentially, which never works over datasockets (in my experience).
We have continued to work in version 7.1 because of the challenges of moving to 8+, but since we can no longer purchase DSC runtime licenses for version 7.1 in order to deploy, it seems that we MUST move forward to 8+ or abandon LabVIEW altogether (which is certainly an option).
For clarification, I am now working with version 8.2 (but I've been fighting with it since 8.0 without much success). If anybody out there can think of a critical step that I might have missed that might cause this, or if there is a known solution, I could really use (and would greatly appreciate) the help. Thanks!

Nobody out there seems to have any answers for this, so I kept pounding on it (and pulling my hair out). In the end I finally succeeded in getting one of my old 7.1 DSC projects to run on 8.2. Here's what I did:
1. I begin with a fresh installation of Windows. I tested it with both 2000 and XP Pro. Vista RC1 will absolutely NOT work!
2. Install LabVIEW 8.2, DSC 8.2, and just the OPC server that I need from the IA OPC CD (in my case the Allen Bradley server)
3. Open the IA OPC server editor, and create a new file with an object in it for my PLC (PLC 5/30, Ethernet in my case)
4. Save, set it as the startup file
5. Run LabVIEW, create an empty project
6. Add an IO server
7. Launch Multi Variable Editor, load project file created in step 6, and bind one variable to PLC address
8. Save all. Uncheck auto deploy for the library, and deploy all.
9. Launch variable monitor, browse to new variable, double click to monitor.
10. This will ALWAYS fail with "server failure". Don't worry, just exit completely out of LabVIEW.
11. Stop the Variable Engine service.
12. Run OPC server editor again, and load up the lpd file from your old project. Modify if needed, save, and set as startup
13. Start the Variable Engine service again.
14. Launch LabVIEW
15. Create a new empty project (I created mine in the same directory as my old 7.1 project resided)
16. Add an IO server, and uncheck auto deploy for its library
17. Save all
18. Run Tools->DSC->Migrate->import scf
19. Convert your old SCF file
20. Add the new library to your project (it will be named LabVIEW)
21. Uncheck auto deploy for the "LabVIEW" library you just added
22. Right click on the "LabVIEW" library and do deploy all
23. Save, and open the variable monitor
24. Browse to a tag in the LabVIEW library, and double click
25. This time it will actually monitor the variable, with a status of "Good"
26. Now you can add your main front panel VI to your project, open it and run it
27. Version 8.2 will select the proper legacy tag read/write VI's, whereas 8.0 does not. The writes however do not work. Replace them with shared variable writes. The reads work fine.
28. The empty project that you created in step 5 is a throw away. It will never work anyway.
29. So far the only variables that I can get to work at all are the ones that I import from an scf file, which is a pain, but if I must create all my tags in 7.1 and import them into 8.2 I will (for now). I may try exporting to Excel and copying variables that work in order to get functional new variables, since binding them in the editor does not work.
I hope this helps anybody else out there struggling with moving to 8+ DSC. I saw a few posts with similar issues, but without ANY answers at all. It's a convoluted solution that doesn't make a lot of sense, but for me it is repeatable.

Using Shared Variables and Initialize Front Panel Binding (to PSP)

Hi,
I use LV DSC RT 8.2.1
I have a Vacuum System That includes signals from - Pumps failure, Valves status, Vacuum gauge, start Pump ...
Each signal is read by a FieldPoint.
All the relevant FieldPoint Channels are read by the Server (a computer in the Ethernet Network) and published to the network in the form of Shared Variables.
I have a client VI that is reading the Shared Variables published by the Server using Front Panel Binding.
Problem :
Some of the Bindings are in the mode 'Write &Read' and that causes some initialization problems.
For example - Valve #1 is Open, and then a User start running the Client VI, (the Valve #1 Status mode is 'Write & Read")
if in the VI the status of Valve #1 is closed (before running it) then the Valve status is changing to Closed.
I want the Client VI to first read the Physical status of the instrument and then to change the Value if the User changes it.
But that's seems to be a problem when using Front Panel Binding... (is it?)
I know I can Deploy a lvlib in the Client Side and Item Bind to the Shared Variables or Use DataSocket.
(Is DataSocket is a Reliable method when connecting to Shared Variables? What are the disadvantages when using DataSocket?)
What is recommended by those of you that are experienced or by NI ?
Sincerely Yours,
Amitai Abramson.

Amitai Abramson,
Hello and thanks for using the NI Forums.
I'm glad that you've read the Using the LabVIEW Shared Variable Tutorial on our website. Check out these other resources:
Network Variable Technical Overview
Troubleshooting Network-Published Shared Variables
Why Do I See Unexpected Value Change Events for Shared Variables Using LabVIEW DSC?
All You Need to Know About Shared Variables
Creating a Value Change Event for Shared Variables
Alternative Method for Using Shared Variables Between Systems in LabVIEW 8.x
What Is The Difference Between Using Shared Variables And DataSocket VIs To Access OPC Tags?
The issue that you are seeing by having "Write & Read" bound items on both the server and client side is essentially a race condition, you don't know which one is being read/written at what time. To resolve this issue I would take a look at some of the documents below.
Using a Local, Global, or Shared Variable in Parallel Loops Can Cause Race Conditions
Using Local and Global Variables Carefully
Tutorial: Local Variable, Global Variable, and Race Conditions
Locking a Shared Resource or Variable in LabVIEW Using Semaphores
You mentioned not wanting to have two sets of shared variables (one on each side), but this is a great method to resovle this issue, that, or you can develope some sort of hand shaking to prevent these race conditions.
I would suggest that in the future when using these forums you try to ask only one question per thread and make it more concise. It's hard to tackle multiple questions and such broad questions as "I want to know all the ways that I can connect to Shared Variables, and I want to know the advantages and disadvantages." I suggest this because we want you to get your questions answered and more concise questions will result in quicker and better answers.
Message Edited by Ben S on 10-01-2009 06:05 PM
Ben Sisney
FlexRIO V&V Engineer
National Instruments

Modbus and shared variable performance in large application

Hi all,
I am preparing to work on an application which is going to reading from up to 500 Modbus input registers on a CompactRIO over Modbus Ethernet using the LVRT Modbus IO Server implementation. I've put together some minor test VIs on the local network to test the Modbus connectivity and understand in the shared variable minding mechanism.
To save potential headaches in the future, do you all have any best programming/proejct management practices for using high channel count Modbus applications? Has anyone done high channel count testing (similar to the link below) but for shared variables bound to a Modbus I/O Server? Any caveats I should keep in mind?
Performance Benchmarks for Network Published Shared Variables
http://www.ni.com/tutorial/14675/en/
Thanks,
Chris
d2itechnologies.com

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.

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

Network shared variables lose binding

Hello,
I am developing an application in LabVIEW that uses network shared variables to transmit data between two PC's on the same subnet. The shared variables work fine when running the VI's in development mode, however, when i build the vi's into an executable I find that they no longer work. Here is what I have found so far:
I deploy the shared variable library on the publisher machine (also happens to be the development machine) through an invoke node in the executable. NI distributed system manager confirms that this does deploy and indeed updates as it should.
For the executable on the subscriber PC I created a second shared variable library (same project) with the same shared variables and bound them to the respective shared variables from the first library by selecting enable aliasing, then bind to PSP URL and browsing to the shared variable I wish to bind it to (e.g. \\hallnet-ellm2\shared variable library\serial Number). The machines listed under browse were listed by name so when I tried this initially and it did not work I manually changed the name of my machine in the URL box to the IP address of the publisher hoping that would fix it in case the subscriber could not resolve the publishers machine alias. So now my bind URL read \\192.168.0.1\shared variable library\serial Number.
As part of the executable on the subscriber I deploy this second shared variable library. NI distributed system manager confirms that this deploys but under quality for an individual variable it has a list of issues (see attached) and the bound variable is not updating. At this point the publisher shared variables are still functioning fine. By clicking on 'edit variable' I can see that the variable on the subscriber is still bound but the PSP URL is now \\localhost\shared variable library\serial number. Changing the PSP URL on the subscriber to \\192.168.0.1\shared variable library\serial number enables the variable to update as expected.However by this time my executable has already picked up the error and does not function.
I think that the issue lies with the bind URL used on the subscriber as for some reason it does not keep the binding configured in the project and instead changes to 'localhost'. Why is this? Should it not stay bound to the address specified in the project?
I have tried changing the IP addresses in the aliases file so that
[My Computer]
My Computer=localhost
becomes
[My Computer]
My Computer=ip of local machine
This did not help.
The shared variable libraries are included in the build spec to go into the support files directory and they are successfully deployed from there on both publisher and subscriber.
I am using LabVIEW 8.6 on Windows XP
Thanks for any help you may be able to offer,
Lee
Attachments:
distributed system manager.JPG ‏74 KB

Hi Lee,
I hope you are well. Thank you for your post. Your application sounds very interesting.
Looking at your issue I was wondering, have you tried lowering your firewalls, as this may be causing the problem.
Also, another option would be to setup a private network. Do you have access to any routers that you could use to link the two machines independent of your IT's infrastructure?
The other thing to try is two other computers entirely. Again, it would be ideal to take them off the network you are on, but it's something to try if my prior suggestion doesn't work. It should work on the original two machines though, and it's likely that different computers won't solve your problems because I suspect the network.
Remember that the client variables must know the location of the variables on the server, so you can't move the server exe around without changing this value.
Make sure to set the network location in the "Bind to Source" option for the client variables.
It is also possible to write a separate piece of code to install on every machine that is responsible for deploying the library and by doing so eliminate the need for programmatically deploying the variables in the original application. However, this won't really help you, because the variables you use in the application have to be the same as the ones deployed in the library, so if you change the library, they'll no longer be linked and they won't receive data. You'd have to create a separate exe for every binding source you wanted to link to, and then have a second, known library for the sake of communication locally on the computer between the ‘deployer’ and the actual application. The main application could then be assigned the responsibility of launching the correct ‘deployer’' if it sees it needs to switch to a different variable binding source. This method is not the most streamlined or effective, but it might work.
Just to let you know, you will need to use the DSC toolkit.
Please find below some knowledge base links that I think you will find helpful in your application.
Using Shared Variables in Executables
How do I Programmatically Change the Data Binding Source for Shared Variables?
I hope this information helps and if you can give these suggestions a go and let me know how you get on, that would be great.
Kind regards,
Prashant M
Applications Engineer
NI UK & Ireland

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.

Shared Variable programatic access error -1967362038

I am trying to read/write about 300 tags from a AB ControlLogix 5561 processor from Labview 2011 on windows XP SP2 through RSLinx Classic OEM OPC Server.
At first, I tried to do everything through front panel data binding through Datasocket, but I've seen that it becomes slow/unreliable when the bound control count reaches beyond 100 tags or so. Wrong values are read/written, some controls just won't bind intially or lose thier binding...it's really odd. So, I've put all of my faith in Labview's DSC module to solve all of my problems.
I installed it on a development system, played around with the programmatic access VI's using the NI's test OPC server and everything worked great. It really looked like the answer to all of my problems but upon installing it on the target system I can't get it to work the same way!
I've created a library of simply 3 bound variables to the PLC through an IO server pointing at the local instance of RSLinx. I am able to browse the PLC tag structure, so at least the link through RSLinx is working to some extent.
Fairly often, when running the seach variable container vi on that library, I get error -1967362038 with explaination "IAK_SHARED". When this error occurs, the same error shows up in the distributed system manager and the shared variables can no longer be read. I can't seem to pin down a pattern but happens every few minutes or roughly ever 3rd or 4th time I start the vi. When it happens, the only way I've found to get things working again is to undeploy and redeploy the library, while watching it in the distributed system manager, then continually loop the search variable container VI for a few seconds and eventually, the variable comes back to life.
Does this sound like an issue with RSLinx? One of the previous posts related to this error mentioned that it may be due to some corrupt files in MAX?
Other network published shared variables (non-OPC) seem to be OK so I think this is a problem related to the DSC module.
I rebooted twice immediately after the DSC installation.
I have uninstalled SQL Server 2005 and the DSC module and reinstalled both. Twice.
What could be causing this error?
Would it be worth while to port over to the NI OPC Server?

Hi pjrose,
First, I notice that this post is pretty similar to a service request that one of my colleagues has been working on. Are you working with another NI Applications Engineer on this issue?
That said, the issue could very well be related to the DSC module. I doubt that the error is a MAX corruption error, at least at present. One thing that would be worth checking would be the connections on your network. Additionally, what are the types of variables that you are accessing, and how specifically are you coding the access to them? If you could post an example of how you're accessing them, that would be helpful.
Best,
Dan N
Applications Engineer
National Instruments

Deploy Shared Variable Engine in localhost

I need to talk to multiple RTs using single computer. It seems
obvious to deploy shared variable engine (libraries) in localhost instead of
RT. However, the problem is the shared variables (read) used in localhost VIs
are not being updated from RTs. But when I am using another local VI to update
the shared variable, it is working just fine. The variable path of the RT looks
like "\\My Computer\Local NPSVlvlib\Test
Data". I think this is the problem why the values are not being updated
because RT cannot resolve the network path ("\\My
Computer\Local NPSVlvlib\Test Data"). Also, I tried to change the shared
variable path in RT but I could not do it. Help Needed!!!!
Solved!
Go to Solution.

Thanks for your reply. I found in this link http://zone.ni.com/devzone/cda/tut/p/id/9900#toc2 that host computer can host the shared variable library and RT does not need the shared variable engine. See below
If your application includes a single host computer and a single or multiple RT targets it is recommended to host the library on the host computer. This will save memory and processor time on the RT targets. Also, by hosting the library on the host computer instead of the RT target, you can reduce the software install footprint on the RT target. The RT target will not need the Network Variable Engine, but will still require Variable Client Support. The Network Variable Engine allows hosting, the Client allows communicating with libraries on other machines. You can see a RIO target with these installed in Figure 4.
That exactly what I am trying to do. Any comments?

Error connecting to shared variable OPC item

I have a DSC application that has a bunch of shared variables. Some of those variables are bound to an OPC server(Eurotherm). When I place controls or indicators in a VI and bind them to the shared variable, some of them get the "green light" and some of them get the "red light". If I hover over the red light, there is a message about an error connecting to the shared variable. However, all the values update and appear to be working correctly. Why would I get this error?

Hi Brian,
Which version of the DSC Module is this? Is the OPC Server that you are trying to connect to on your local machine or on a remote machine?
Have you tried deleting the front panel object and redragging it from the project explorer? What type of value is this (boolean, double, etc?)
What are you referring to when you mean an "identical instrument" - are you connection to two different OPC I/O servers in your projects?
Would you be able to post a screenshot of this error please?
Best regards,
-Sam F, DAQ Marketing Manager
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Shared Variable Engine on Windows PC w/o full install of LabVIEW

I have the NI Developer Suite (8.20) and need some conformation before I get too deep in a project.
First of all, it is my desire to become very efficient on develop compiled executables with LabVIEW 8.20 as my NI Developer Suite license allows me to deploy these programs to any number of machines without facing copyright infringement. I have been successful with this to a certain degree, but am still having problems in the testing stages of my application especially in cases where the hardware I am trying to target does not exist on my developing station. If anyone can point me to white papers that would help me get the mindset to develop in this way, I would appreciate it.
Onto the topic of this post:
I am just scratching the surface of the shared variable interface that is available in LabVIEW 8.2. My project involves two computers where both of them need to share variables back and forth from each other. I've been reading everything I can get my hands on and I am having a hard time answering my unlying question: Is it possible for both of these machines to be running compiled LabVIEW programs and still manage the shared variables between them? That is to say, can one of the machines have the Shared Variable Engine running on it as a Windows service, or compiled into my application executable.
I've read that I can access shared variables from my compiled LabVIEW application through NI-PSP. I am wondering what my limitations would be sans-LabVIEW installation other then the troubleshooting head ache you get from developing applications without direct access to the hardware.
Thank you for your time and submissions.
-Nickerbocker

I am trying to get the "Shared Variable Client - Server" project example compiled so that both the server and client vi's can be run as executables on a standalone machine.
I have created 3 build specifications:
1. "My Server" which is the compiled EXE of the server.lvib. Added that entire library to the source.
2. "My Client" which is the compiled EXE of the client.lvib. Added that entire library to the source.
3. "My Installer" which is the installation package of the vi's and NI supporting software. In the additional installers I have added:
* NI DataSocket
* NI LabVIEW Run-Time Engine 8.2
* NI Measurement & Automation Explorer 4.1
* NI Variable Engine
* NI Variable Manager
* NI-DAQmx 8.3
Some of those are added for future needs. Installed the package on my target machine and run the server executable it appears to run fine but I get various error messages from my client.exe package (which I won't go into detail here, yet). Upon stopping the server I get the message "LabVIEW: (Hex 0x8BBB0005) Unable to locate variable in he Shared Variable Engine. Deployment of this variable may have failed."
I check the services running and see that the "National Instruments PSP Server Locator" and the "National Instruments Variable Engine" are both in the list and "Started." I open up the Variable Manager that has been installed on my target machine and manually add the "waveform" and the "command" variables under a process I call "server" and start the process. After that I start my server.exe that I have compiled from the server.lvib library. The process gives no error messages until the stop button is pressed, and then I receive the message "LabVIEW: (Hex 0x8BBB0011) The connection to the server was disconnected."
The compiled programs run fine on my development machine as well as the uncompiled VIs within the LabVIEW development enviornment. Something tells me that I simply do not have the Variable engine properly configured on my target machine. Also, the process and variables should automatically be populated under "Local System" in the Variable Manager, right? I do not need to add them manually, or do I?
Thanks for your input!
-Nickerbocker

Replace local shared variables

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