Shared variable version on host and RT target

Hi,
Is it possible to use different shared variable engine on host computer and RT target? We use shared variable to communicate between RT target and host computer. Once the products shipped to customers we will keep the software on RT target unchanged but we would like to keep updating the program on the host computer with newest LabVIEW version. Is it possible to just update the host computer without updating the RT target?Thanks for help!
Tao

Hi Tom,
Are you getting an error code or some thing else?
Attached are two zip files. The 8_5.zip is a LabVIEW project that was written in 8.5 and deployed to a cFP. The 9_0.zip is a LabVIEW project written in LabVIEW 2009 (9.0), that reads the shared variable off of the cFP running the 8.5 code.
This works for me, so if you could give a little more detail, hopefully I can help you out.
Justin Parker
National Instruments
Product Support Engineer
Attachments:
8_5.zip ‏36 KB
9_0.zip ‏30 KB

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Are you making them network published shared variables and binding them to each other? This doc gives a pretty good step by step:
http://digital.ni.com/public.nsf/allkb/7815BCE435DCC432862575DA006FEBF8
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Hi,
I want to share data between a RT-target and one or more hosts (LV 8.6.1). The network shared variables are deployed to the RT-Target. According to NI accessing shared variables from another project or host has to be done by defining a shared variable on the host and aliasing it to the NI-PSP data object on the target.
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The host project:
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Attachments:
AliasTestWrite-RT.vi ‏8 KB
AliasTestConsumer.vi ‏8 KB

Dear Mr. Quade,
thank you for posting at the National Instruments Forum. There is a known issue with the path of the bound variable with LabVIEW 8.6.1
Please download the patch for LabVIEW 8.6.1, it should solve your problem:
http://joule.ni.com/nidu/cds/view/p/id/1255/lang/de
Best regards from Munich
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Shared variable, missing data, the same timestamp for two consecutively data

hello
I have a problem with missing data when I read from a network published shared variable.
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In a host VI on my Laptop (HP with WinXP Prof.) i'm writing data to the shared Variable "data". Between two consecutively write operations is a minimum of Milliseconds waiting time. I use that because I want to be sure that the timestamp for each new data value is different then the preview one (resolution shared variables is 1 ms)
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Simplified Example:
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Would it change something when I host the shared Variable on the RT-System ?
Thanks for your help
Regards
Reto
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Hi Reto,
I had a look on your modified Example.
Because the Shared Variables didn`t work like Queues or Notifiers (No Event or Interrupt when a new value has been written. And for sure the´re not possible over a network) you will see the issue, that the code is reading the values more often with the same timestamp (Polling Problematic) if the reader is faster then the writer. And because the timestamp is written with the value you´re able to program like you do. Filter out whats duplicated when you have the same timestamp.
Everything is described in here:
http://zone.ni.com/devzone/cda/tut/p/id/4679#toc1
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Regarding your question: Would it change something when I host the shared Variable on the RT-System? --> No
In my experiences, you should consider to place the Shared Variable Engine after asking some questions regarding the application.
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Does the application require datalogging and supervisory functionality?
Does the computing device have adequate processor and memory resources?
Which system is always online?
And you`re right the smalles time interval you can see in the timestamp is 1ms.!
What you also can do is working with an enabled "timed out". This might be more performance efficient than reading the timestamp.
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I hope this helps
Alex
NI Switzerland

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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.

Hello Dave,
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Shared Variable Deployment and Hosting

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There are some questions you need to ask yourself before you make those decisions. The following tutorial has that covered under the title 'Recommendations for Shared Variable Hosting Location'. Have a look and let us know if you have any further questions:
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RT target slows down after updating with a shared variable

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Hi Mark,
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Attachments:
Host Data In.ctl ‏33 KB

Modbus Ethernet read and write to a Eurotherm 6180XIO Modbus server using LV8.2 shared variables

I am having EXTREME difficulty trying to establish communications with a Modbus device using LV8.2 shared variables. The device is a Eurotherm 6180XIO Datalogger configured as a Modbus master. The PC and a cFP-1804 are slaves. All IP addresses are set correctly. This approach using shared variables would seem simple, but I can't find any examples or proper guidance on how to get it working. I am trying to avoid having to mess around with TCP/IP, OPC, or any other old-fashioned method.
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Multiple versions of Shared Variables on same network

I have 2 seperate reactors working on the same network each deploying ~50 shared variables (different names on each process) communicating with LV 8.5RT running on FP hardware. One of the reactors is requested for new features and to be upgraded. Is it possible to heve 2 different shared variable engines (8.5 and 2010) and versions on the same network and client computer, or am I asking for trouble.
Paul Falkenstein
Coleman Technologies Inc.
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Solved!
Go to Solution.

I believe we address this here: http://forums.ni.com/t5/LabVIEW/multiple-versions-of-Shared-Variables-on-same-network/m-p/1487366#M5...
Sam S
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National Instruments

Shared Variables, Scan Engine & Multiple Targets

I am seeking some general advice about the structure of my LabVIEW project.
The project consists of a laptop with LabVIEW, and a joystick connected, and a CompactRIO connected via ethernet. I had been running the cRIO in FPGA Interface mode, however a change in some things caused the project to have to be shifted to scan mode.
As of now, the code on the laptop updates shared variables on the cRIO, and reads from shared variables on the cRIO for monitoring. I want the shared variables hosted on the cRIO because it will also need to operate without the laptop connected. Before switching the cRIO to scan mode, I found that I had to first run the laptop code, and then run the cRIO code, or the shared variables would not communicate properly. Now that I have switched to scan mode, I have to run the cRIO code first, and even then the shared vars do not communicate properly for more than a few seconds, and are much laggier.
My ideal project solution is a system that can run with or
without the laptop connected, and obviously not having all these shared
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have the user run the laptop code if necessary, but in the past this did
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I am really confused about why this is happening. Hopefully I have explained my problem well enough. I don't really want to post the entire project on here, but I can email it to people if they are willing to take a look at it. Thank you for taking the time to read this.
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I do this type of stuff all the time...
Move all your NSV libraries to the cRIO. From the project you must deploy to the cRIO and from then on they are persistant until you reformat.
From your windows HMI app, you can place static NSV tags on the block diagram or use the dynamic SV API to R/W. Also you can bind HMI controls and
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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

LABVIEW 2012 - shared variable error during programming of NI CRIO 9023 and TPC 2212

HELLO,
i am using CRIO 9023 with TPC 2212 and LV 2012. I want to develop a stand alone app which has a front panel on TPC. at first i am building a simple app with two controls variables, one is a sliding bar on TPC Vi and the other one is the while loop variable "i" on CRIO VI. i used shared variables.
first i creat shared variable on CRIO side and access this on TPC Vi. I COMPILE both Vi,s and they are working fine. But when i created the slide bar control in TPC VI, compiled and deploy the TPC Vi, it get deployed in TPC. But when i start compiling the CRIO VI an error mesage occured as follows;
I have tried every option to best of my understanding like formating crio then installing all softwares including Network variable engine etc. i also go in properties of the executable file of TPC Vi and go in properties-shared variable- then check the "deploy variable in application" option . below is image displayed.
I am in despirate need for solving this problem as i have to develop the final app for testing soon. can some one help me regrarding this.
REGARDS

I would not recommend using shared variable engine. It is supposed to make things easier, but in fact, you will spend more time troubleshooting why it is not working than you will actually coding an alternative solution.
Try the Simple TCP Messaging instead.
http://zone.ni.com/devzone/cda/epd/p/id/2739
Machine Vision, Robotics, Embedded Systems, Surveillance
www.movimed.com - Custom Imaging Solutions

Shared variable version on host and RT target

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