Creating and loading 4000 shared variables

I need some help laying out the design of this system. The data is coming over reflective memory. I've written a dll and a simple server to do the interface between the reflective memory and shared variable engine. Everything seems to be working. The problem I am having is with scaling the application up to handle approximately 4000 variables. I have a spreadsheet to manage the reflective memory allocation and can use it to import the shared variable definitions with the names from the system that is writing the data.
I am having trouble deciding on the best way to proceed. I would like to read a buffer from reflective memory instead of reading 4000 times. I also would like the server to read in a file that defines the association between the shared variable and reflective memory address. The problem I am having is getting the data out of an array into each of the shared variables. I don't see a way to load the value of a shared variable using the property node (so that I can do this inside a loop). I also can't setup an alias that would access an array element. I don't want to manually create 4000 variables.
Any ideas would be appreciated. Thanks.

I have never had to resort to creating Shared variables programatically so I will leave that for others.
I would cheat.
In LV 7.1 DSC i could import my tag config from a csv file. After importing and saving in LV 7.1 I could let LV create the SV's when the code is updated.
THat all assumes I will only have to do that one.
I have used the interupts fired when SCRAMNet locations update to "steer" the value to appropriate code which could then in turn update the SV using a datasocket write since I can compose the URL for the SV dynamically.
Just sharing ideas,
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

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I have used a data socket open to open a connection to all variables when my program starts. I then use datasocket read on the opened connections to write to an array. This works fine until I try to write to one of the variables using a shared variable node. The variables writes can take from 4secs to 2 mins. When I remove the shared variable node again all is fine. Also when I stop using the data sockets, all is fine.
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Hi
Sorry I forgot to mention the LabVIEW version, its 8.20. I have tried saving the shared variable node as a sub VI and it makes no difference.
Attached is a stripped down version of the software. You will not be able to connect to the IO server because it requires some Wago hardware and software. You may spot something I have done wrong with the I/O servers, variables or sub VI's.
The main program that runs is called 'HMI Engine' in the 'Framework' folder. There may be some other things in the project that aren't used in this example. I have removed all but the variable connection part of the code.
I hope someone can help!?
Thanks
Mark.
Attachments:
HMI Test.zip ‏144 KB

How do i create and pass a global variable from one vi to several sub-vi's?

Hi Guys,
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Hi Parga,
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Like a variable declared at web dynpro component context level can be used among all views.
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Initialize the shared variable

"From the issue description it seems that the Shared variable needs to be reinitialize.
Create a formula to initialize the shared variable value and place it in appropriate section of the Main Report based on the section in which you are displaying shared variable value of the Subreport." (post from Poonam Thorat 7/7/08)
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Hello
Lets say you have a report like this
Report Header
Page Header
Details
Report Footer
Page Footer
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whileprintingrecords;
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If you needed to use this shared variable in the Details section, then you would place the Rate formula in the Report Header, or Page Header (above Details so that it is created before the Details section is created)
In details lets say you have some other calculation - Commission
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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/
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If your application can deal with it I would recommend staying clear of the 'Networked Published' option.
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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.
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Data Logging a programmatically created shared variable of cluster or array datatype into citadel DB

Hi,
Is there a way to log a programmatically created shared variable of cluster or array datatype into citadel DB?
I have attempted to programmatically create a shared variable of type 'double' and was able to successfully log the same into Citadel DB. In the attachment, Please refer to the attached project SV_TC.lvproj and specifically to SV_W.vi for the code that i have used (W.png file shows the dB in MAX and shared variable in NI Distributed System Manager)
However when i tried the same approach to create a shared variable 'array of double', i noticed that traces are not getting created and hence data logging isn't happening into the Citadel DB. I was however able to write and read the shared variable array without issues. The same is true with cluster datatype also. Please refer to SN_NW.vi for the code that i have used - only difference from SV_W.vi is that i have tried to create a shared variable of type 'array of double'
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Attachments:
SV_TC.zip ‏3925 KB

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Why do Single-Process shared variables create a single variable VI in my dir.

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Attachments:
Shared Variables in Directory.JPG ‏383 KB

Hi davidreed10,
This is a known issue with single process variables that are saved in a
project that has the .lvproj and .lvlib files initially saved in different
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previously reported to our R&D department with the ID #56580, and
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Network Datastreams and FIFO Shared Variables

Does someone know why one would use a Network Datastream as opposed to a network published shared variable with FIFO enabled? Seems like they would be identical except that the Shared variable could potentially have multiple listeners.
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Craig

Hey Craige
You are correct that a major difference between Network Steams and Network Published Shared Variables with RT FIFO enabled is that the Shared Variable can publish to many computers at once. There are a few other differences that are outlined in the comparison table in this article
http://zone.ni.com/reference/en-XX/help/370622J-01/lvrtbestpractices/rt_gui_bp/
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http://zone.ni.com/reference/en-XX/help/371361H-01/lvconcepts/networkstreams/
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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.
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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 variables location

   I'm starting a fairly large project and wanted to organize it properly. When I needed a shared variable, I first created a new library. I was able to specify the location of this library in a sub-directory within my projects file structure.   Then I made some shared variables (single process). After saving the project, the shared variable files appeared in the main project directory, at the same level as the .lvproj file, not in the subdirectory where the library was created.
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Thanks,
    Dave
David Thomson Original Code Consulting
www.originalcode.com
National Instruments Alliance Program Member
Certified LabVIEW Architect
There are 10 kinds of people: those who understand binary, and those who don't.

   Thanks for the reply. Unfortunately, the problem remains:
   I first create the library explicitely, before creating any variables. I saved the library to a subdirectory. Then I create variables. When the variables are instantiated within a VI, at some point LabVIEW automatically creates vi files on the disk corresponding to these variables. These VI files were placed in the main directory with the project file, not in the subdirectory where I put the library. This is surprising to me and I would think this is a bug.
    My solution at this point was to create a "Project" subdirectory. I put the .lvproj and the .lvlib file in that subdirectory and now the shared variable vis appear there as well. This is a kludge.
   My main question at this point is: can you specify where these shared variable VI's get created and stored? I suspect that you could edit the .lvproj file or other xml files to change the share variable paths, but that is inappropriately difficult. I tried just moving the files to where I wanted them, but then the variables don't load. I managed to reload them, but at some point, they recreated themselves in the original location.
   At a minimum, the shared variable VIs should create themselves in the same directory as the .lvlib file that they belong to. At least you can specify where the .lvlib file lives.
Regards,
   Dave
David Thomson Original Code Consulting
www.originalcode.com
National Instruments Alliance Program Member
Certified LabVIEW Architect
There are 10 kinds of people: those who understand binary, and those who don't.

I am trying to connect Dashboard shared variables to a server on a different subnet. Any ideas?

My goal is to control a device that is connected to our wired network using an Android tablet via Dashboard. I have created a vi with shared variables that controls the device as expected when it runs on a computer that is connected to the same wired network. The problem is that my Android tablet running the Dashboard app cannot connect to the shared variables on the PC running the vi on the wired network.
Our wireless network is on a separate subnet from our wired network. I am able to ping my Android tablet from the PC on the wired network but when I try to connect a variable in Dashboard, the PC running the SVE cannot be found. I tried listing it in the alternative server settings window and it still did not work. The only way I have been able to get around this is to run the vi which launches the server on a laptop that is connected to the wireless network and the wired network at the same time. My tablet can then find the server and my VI can connect to the instrument that is connected to the wired network. The laptop is somehow acting as a bridge between the subnets. I need to find a way for the Dashboard app to connect directly to the PC on the wired network. My PC IP address is 192.168.0.105. My Android IP address is 192.168.10.93.

Data Dashboard doesn't care about subnets, but it has to be able to access the server using the right ports. There is probably a firewall blocking the shared variable ports. This document explains how to configure a firewall to allow shared variables to be accessed. Your challenge will probably be to figure out where the firewall is and how to configure it.
It is also possible that the router that your Android device is connected to doesn't know how to route to the other network. Again, that is an issue with your router that you need to resolve.

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How does one set the Bad Status of a Shared Variable in 2009?
IE). I have a custom device that communicates via TCP/IP. I wrote my own I/O server that handles this communication and publishes a set of Shared Variables that my Main Application displays on a screen. These variables are all doubles and hold pressures and temperatures. If my I/O server in labview loses communication I would like to be able to set the status of the variables to bad so they will set off an alarm. In our main application we have colour indicators that are able to display this status. For example the background goes yellow for all indicators that are in "HI" alarm status, red in "HI HI" and orange when "Bad Status" (disconnected).
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None of the Shared Variable IO Properties can be configured to allow you to set the alarm. You can only configure the properties such as turning the possibility of the alarm status on/off and the priority, name etc. You do not have the ability to indicate that this shared variable is in alarm because your custom server has encountered a problem. I've talked to tech support about it and I've been informed that this was something that was removed when the shared variable engine was introduced. I've been told informed that the recommended alternative is to create an additional boolean shared variable that will contain the status of the items, or to write some sort of unique garbage value to the actual tag value to indicate there is a problem with it.
I now have to come up with a new way of providing this information. I just find it will likely be a poor programming choice because now my entire system will have to handle "tags" differently based on what hardware is being used. (IE) if its coming from a custom I/O device or from an OPC / Modbus etc capable device.

Creating and loading 4000 shared variables

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