Shared Variable Read Access Denied from Fieldpoint

I've posted this in the Fieldpoint forum, but I think I may get more responses here:
I've created a shared variable bound to a single analog input (AI) channel on my fieldpoint 2120. When I attempt to read from this variable in my VI, I get the error: "Read access is denied to the shared variable."
BUT, when I view the variable in the shared variable manager, the analog signal is updating correctly and continuously.
Anyone know what I may be doing wrong?
Thanks!

Link to post in Fieldpoint forum.

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Analoge shared variable read Problem

Can any body help me in reading analogue shared variable read in LabVIEW 2009 dynamic event structure. I have tried to read the above tag through Tag Reader VI but i have experienced too much delay in first read for real data i.e. Plant data from PLC. when this particular VI executes it take minutes to display the data. if some needs its code i can provide it. Thanks in advance

This seems to be a LabVIEW problem, so please post it over in the LabVIEW forum.
(the feedback forum is for problems with the website itself)
LabVIEW Champion . Do more with less code and in less time .

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

Lion SMB file sharing with windows "Access Denied"

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I have this issue as well. and I have it on multiple configurations. My windows machine can't open an fla file on a osx lion share. another person working on the same project (on a different network setup) can't to it either. seems like something broke with lion that was working perfectly fine on snow leopard.

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Hi,
Plesase check ntfs permisions and share permssions of the shared folder. You could try to set share permissions to Full Control for the Everyone group to see if the issue still exists.
Share and NTFS Permissions on a File Server
http://technet.microsoft.com/en-us/library/cc754178.aspx
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Mandy
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are trying to better understand customer views on social support experience, so your participation in this
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File read access denied for signed applet

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I have also made a CLI application that uses the above code and it works perfectly.
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A solution to this problem is not clear, but possibly, serving the pages from a trusted server, the java script will be trusted, some documentation seem to indicate.

Use of Shared Variables for data transfer from a RT traget to a desktop application

Hi,
I want to adopt the shared variables to share data in an existing distributed application comparable with the T3 Benchmark configuration in this document:
[1] http://zone.ni.com/devzone/conceptd.nsf/webmain/5B4C3CC1B2AD10BA862570F2007569EF
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To use the shared variables instead of this RT FIFO + TCP/IP implementation I need to read the shared vairable buffer at once each time the desktop application reads the shared variable.
But according to this quotation from [1]:
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this seems to be impossible. Am I right?
Are there any suggestions to circumvent this problem? Or are shared variables not made to share data between unsynchronized processes without data loss?
Regards Till

You can use the error-cluster to detect the end of your queue. The erroroutput of the shared variable will return a -2220 Warning, if it reads a value it has read already before. I attached a modified example and saved it for 8.2 I hope you can open it.
Attachments:
readbuffered82.zip ‏51 KB

Network-Shared Variable - read string with CVI

I need to read an NSV string with CVI. I have been digging into accessing and writing NSV with CVI, but they are all scalar value. What should I do with strings, clusters and arrays?

'm an employee at National Instruments and I wanted to make sure you didn't miss the Network Variable API that is provided with LabWindows/CVI, the National Instruments C development environment. The the Network Variable API will allow you to easily communicate with the LabVIEW program over Shared Variables (http://zone.ni.com/devzone/cda/tut/p/id/4679). While reading these links, note that a Network Variable and a Shared Variable are the same thing - the different names are unfortunate...
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File Read: Access Denied

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FROM FEjava.io.FileNotFoundException: C:\ProgramData\Adobe\Photoshop Elements\5.0\Locale\en_us\How-Tos\recipes\adobe\013\020 (Access is denied)
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Err, he said the file is being read. How will making it not read-only help that?
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Mangement Tasks access denied from Device manager

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I'am using admim account.
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Hi,
LMS 3.2 Solaris 10
There are 3 functions available with device center : Tools / Reports /Mngt Tasks.
I select a random device => i have just Tools and Reports functions. I remove and re-add this device from DCR, there are the 3 functions.
Same thing for 2000 devices. Never had this problem before the package update. Thx

Not able to access Network Shared Variable when deployed in PC

Initially, when we deploy a Network Published Shared Variable in PC and try to access the same (Read/Write) from RT, we get an error/warning "-1950679023". But when we access the same variable from the PC, it works fine. In the distributed system manager, we can see the variable getting deployed. Also the value changes in Distributed System Manager if we write a value from PC. The attached image "Shared variable Issue.png" will give more understanding of this issue.
The other way round it works fine i.e deploying in RT side and accessing from both RT and PC is working fine.
We also see that the network adapter settings is not loading properly in MAX, if at all we install any software in RT. With no software installed, it loads properly.
The following were the steps that we tried to solve the issue.
1.Flushing the entire NI software and Re- installing again
2.Formatting the RT(PXI).
3.Removing the EtherCAT Card and testing.
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Attachments:
Shared variable Issue.png ‏491 KB

First Root cause needs to be identified before any actions.
I would suggest first check if you can access the shared variable hosted in PC from RT using other ways like using SVE API (Logos and PS protocols, Datasocket etc..)
Check if antivirus or firewall is playing...
Check the same experiment with some other PC if you can.
You can also try creating another Shared Variable in RT and binding the same to the PC and try to access it...
Since you have did all the reinstallations already
Best Regards,
Vijay.

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,
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Hope this gets you headed in the right direction. Let us know if you have more questions.
Thanks,
Dave C.
Applications Engineer
National Instruments

Why should you explicitly open and close shared variable connections?

I'm looking into switching over from the old Datasocket API to the new Shared Variable API for programmatic access to shared variables, and I noticed that LV doesn't seem to have any problems executing Shared Variable Reads & Writes without first opening the connection explicitly. That is, I can just drop in a shared varaible Read VI, wire a constant to the refnum input, and it will work. I'm wondering, then, what benefits are offered by explicitly opening the conenction ahead of time...?
I guess I could see some cases where you want to open all necessary connections in an initialization state of a top-level state machine, particularly if you want to use the "Open & Verify Connection"---so you could jump straight to an error case if any connections fail. But other than that, why else might one want to explicitly open the connections.
And, along those lines, are there any problems with implicitly opening the connections? One reason why I am hesitant to open them explicitly is because for one of our applications, we need to be able to dynamically switch from one variable to another at runtime. It would be nice to just switch the variable refnum (wired to the input of the Read function), without having to manually close out the old connection and open a new one. A quick prototype of this seems to work. But am I shooting myself in the foot by doing so?
Thanks in advance.

I'd expect there's a very small number of people at NI that would know the answer to the detail you're asking for. But, let's try to extrapolate from this rather old post to see if we can understand what they're forming their impression on.
The shared variable has to have some sort of reference going on in the background. It looks like they're calling this a connection. It's how LabVIEW knows where to find this variable on the network. We can also see this reference certainly exists if we're opening/closing the reference in the explicit method. You see the connection as just a string referencing the variable by URL. This "reference" has to be stored somewhere. No matter how we're looking at this, we're aware there's a reference of some sort stored.
Now, we'd want to look at what would cause this reference to go away. If you open/close explicitly, it's easy to see it goes away at the close. If it's implicit, when would it make sense to close it out? The VI can't be expected to guess where it's done being referenced and close it out. This puts us into a situation where the soonest it could close is when the VI ends. From my experience, references tend to be wiped when you close out LabVIEW. It's this kind of idea that makes the FGV possible. I wouldn't be surprised by Morgan's claim here.
If we look at scalability, you're talking about two different topics. You're talking about adding an extra open, close, read, etc rather than just a few wires. That certainly would look a mess. In terms of the dynamic swap that was being discussed, we wouldn't be adding all of those. The concern would be if enough connections were opened it'd start to behave similar to a memory leak. This could be something that works with a smaller number of variables. If you continue to scale, it becomes problematic. This is why they suggest it's not scalable.
To your questions:
Does LV allocate some kind of session in memory using that string as a lookup?
It would HAVE to allocate some memory to hold that string. Otherwise, it'd be pointless to even have the reference.
Does it reuse that session if other parts of the application reference the same variable, or does it create a unique session for each referencing call to "Read Variable.vi"?
I would expect this to be "it depends." With the implicit method, I would expect it to open a new reference in each point it isn't wired. This is similar to int x,y = 5; x and y share the same value but are their own unique memory location. If you wire the reference to the other points, it should use the same reference. This would make more sense to me than the program seeking out any other potential usage of the variable in the application to see if there's already a reference open. I could be wrong, though.
And what resources does this "connection" actually represent?
At best, this is just the string. At worst, it's the string and the TCP socket. I'd lean towards the first. Opening and closing sockets should be relatively easy in most applications. But, it also wouldn't surprise me if it holds the socket.
I'm sure others have a better understanding than I do. But, that's what I'd expect for anything you've asked.

I/o server shared variable not working in deployment system ( error no-1950679034 (0x8BBB0006) (Warning))

Hello ,
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First Root cause needs to be identified before any actions.
I would suggest first check if you can access the shared variable hosted in PC from RT using other ways like using SVE API (Logos and PS protocols, Datasocket etc..)
Check if antivirus or firewall is playing...
Check the same experiment with some other PC if you can.
You can also try creating another Shared Variable in RT and binding the same to the PC and try to access it...
Since you have did all the reinstallations already
Best Regards,
Vijay.

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Hello!
I am running a cRIO 9075, which is publishing network shared variables.
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hi,
in which way to you read your shared variable? If you read it before you write a value "into" the variable it may couse this waring.
Have you tried this?
http://digital.ni.com/public.nsf/allkb/7DBC2C3E95AFD85C86257442005CF74C?OpenDocument

Shared Variable Read Access Denied from Fieldpoint

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