Problem bound variables(shared variable)

hi , I'm trying to take values from step7 using OPC server, there is no problem sending the values . the only problem is that I can't get the negative values knowing that in OPC server the negative value is seen . when I use an indicator in labview I'll get 4.29 for negative values . I dn't know where is the problem .

riki35 wrote:
as it is indicated in the OPC it is in float point :/ . what doyou mean by endianness ??
http://en.wikipedia.org/wiki/Endianness
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Coercion problem when using Shared Variable

I have a curious coercion problem when using Shared Variables. I want to share the state of a State Machine, which is an enum saved as a control (typedef) called TYPE State (see attached). I create a shared variable called State and define it as a Custom Control, using the just-mentioned typedef. So far, so good. I've attached three simple VIs -- the first one, Init State, simply wires a constant to the input of the Shared Variable to initialize it -- the wired constant is, of course, defined by the typedef. However, the Get State and Set State, meant to wire an indicator (for reading the state) or control (for setting it), develop coercion dots when wired into the Shared Variable. Why? How do I get rid of the dot? [I suppose I could abandon my typedef and custom control, but the beauty of typedefs and custom controls is that it "enforces" rules, lets you use enums for clarity, keeps the code "honest", etc. -- I'd hate to give that up just to get rid of a dot!].
On a related note, the code seems to work. This is much too simplistic to do anything, but if you open Set State and Get State, set the state to anything, run it (it immediately stops, of course), then run Get State, you'll see the chosen state appear in the indicator. So it does appear to work. The "error" (coercion dot) may, I suppose, be a "bug" in Labview because it can't figure out the mapping of the (very simple!) Custom Control, but if so, I hope it gets fixed quickly!
Bob Schor
Attachments:
Coercion Problem1.zip ‏38 KB

Hello Bob,
I am also seeing this behavior, I will escalate this question to our LabVIEW developers and post again here no later than next Tuesday, November 27th as National Instruments will be closed for the remainder of this week.
If this issue does turn into a product suggestion, I would suspect the workaround would to live with the coersion dot for the time being.
Enjoy the holiday
Regards,
Erik J.
Applications Engineer
National Instruments

Indicator bound to shared variable

Does anyone use indicators that are bound to shared variables? How is it working out for you? I inherited an app that has a gazillion SV's and want to simplify a few things. Thanks in advance.
PaulG.
"I enjoy talking to you. Your mind appeals to me. It resembles my own mind except that you happen to be insane." -- George Orwell

They've worked out great for me. I have quite a few indicators of various types to display telemetry in the UI to the user during a test. The shared variables are all written in a particular background thread. I don't use a "gazillion", though, perhaps no more than 40. I'm able to read, process and write the shared variables (and see indicator updates) at a 60 msec rate under Windows XP on a PXI controller.
“A child of five could understand this. Send someone to fetch a child of five.”
― Groucho Marx

Problem Sharing Variables between 2 machines

I am having problems trying to create a project that would share variables between multiple computers. I am using Labview 8.2.1 (I am new to 8.2.1 and Shared Variable).
here is what i did:
1. I created the project with Client and Server VI's and a library containing shared variables, which both of them call
2. I placed this project onto 2 computers (XP on a local workgroup, no firewall, see each other).
3. On one of the computers I bound all shared variables to their counterparts on the other computer
The system is "almost working"
The problems are:
- I initially used wrong type variables for few items. I then modified the variables in both VI's and Shared Variable libraries and repeated the Steps 1-3 above.
But the sysrtem has some sort of a buffer somwhere, because it keeps bringing the old types of shared variables back (when I monitor them using Shared Variable Monitor).
- When I do binding to source, the system shows wrong variable types (for example DBL instead of U8).
- It takes almost a second to write and read shared variable (my network is quite fast)
I saw that the Labview Example with Server and multiple Clients uses 2 sets of shared variable and they bind - separate sets (different names) fro client and server within the same project. Do I have to do this or is this done just to simplify bindinga nd future distribution?
Is there a buffer/setup/file that I need to clear to get rid of "old" shared variable assignements? (I tried undeploy/deploy - does not help...)
Thank you very much,
Gleb.

Hi Gleb,
It sounds like the shared variable is not getting completely undeployed from the shared variable engine. I would recommend opening the shared variable manager and undeploying the library from there just to see that it is no longer in the engine. Then, redeploy the library and rebind your variables to the host library that you have deployed.
It is not necessary to have different sets of variables for client and host. The important part of the variable is what it is bound to, not necessarily what it is named. So just undeploy your variable, double check the settings of the host variable, then redeploy using the variable manager and rebind your client variables.
I hope this helps,
Brian Coalson
Software Engineer
National Instruments

Blink while alarm on using shared variables with remote panel

I am creating an application where I have front panel indicators data bound to shared variables. I also set it up to have them blink when the alarm is on. I am using the DSC module.
This works great under the development environment. But when I connect using the remote panel, I can no longer see the blinking indicator if there is an alarm. I can see the blinking indicator on the machine that is running the program, but no on any of the remote panels (I have no problems connecting to the remote panel and controlling the program).
I have the remote panel set as embedded, since I want the user to be able to change some settings over the network.
I am sure I am missing something simple, any ideas??
thanks
Kenny

I have been using IE6 and Firefox, and I have found that the blinking does show up, if you refresh the page. And then if the alarm stops and the blinking stops, you will not notice it until you refresh again.
Kenny

Reading shared variables

hi ,
im having problems reading a shared variable value from a vi ,
i created a project library , periodic i/o server deployed it. created the shared variables i needed . bound them , created my new vi draged the shared variable i wanted to read , just a time value , set it to a indicator , then ran the two vi s the triangle has apeared on both the main vi and the hmi vi ,and is green , no conflicts arose , but the hmi vi isnt displaying the data ,
both vi s are on the same computer , have i missed somthing ,?

Hi Vadajooz,
Good Morning and I hope your well today.
I was wondering how you got on with your application and if you still require support?
If so, I would be interested to know what version of LabVIEW you are using?
I would make two simple VIs, one to write to the variable and one to read from the variable.
1. Create the bound variable.
2. Deploy the library, make sure it appears in the Distributed System Manager (DSM - LabVIEW 8.6+) or Variable Manager (LabVIEW 8.5 - ).
3. Run the writer VI, for example, just have a switch (true/false) and when you change the switch state does the status update in the DSM or Variable Manager?
4. If so, then run the reader VI, is the status matching the writer and there DSM/Variable Manager.
*DSM/Variable Manager can be found by going to tools>>... in the VI toolbar.
If you are still having problems,
A. There is a known issue with bound variables in LabVIEW 8.6 - so I can inform you on this if you are using it.
B. I would confirm that the variable is deployed - to do this right-click the library and select Deploy All.
C. Make sure you write to the variable before reading from it.
D. Add error cluster indicators and note any errors you see.
E. Please attach your simple (test) project - so we can confirm its correct.
I hope this helps,
Kind Regards
James Hillman
Applications Engineer 2008 to 2009 National Instruments UK & Ireland
Loughborough University UK - 2006 to 2011
Remember Kudos those who help!

Issue with use of shared variables in Crystal Reports 2008 Offline Viewer

Hi,
I have a report that contains a number of sub-reports which include drill-down functionality. The report returns data relating to an individual team with the user being able to view top level summary information in each area from the parent report and then drill into the sub-reports to view see more detail. The data returned by the sub-reports is filtered, using sub-report links, based on the team code parameter value given by the user. This parameter field resides in the main report.
One of the values returned by the main report is the team name. This is passed to each sub-report using a shared variable and each sub-report displays this team name as part of a heading.
This all works fine in Crystal Reports 2008, but when a report, containing data, is opened using Crystal 2008 Offline Viewer there is a problem with the shared variable. The value is displayed correctly when the user initially drills into the sub-report. However, when the user begins to drill into grouped data within the sub-report the value passed to the sub-report using the shared variable disappears.
How can I ensure that, when a report is viewed using Crystal Offline Viewer 2008, the value within the shared variable is not lost when users drill into grouped data within sub-reports
Thanks
Stuart

Please re-post if this is still an issue or purchase a case and have a dedicated support engineer work with you directly:
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How to read shared variables inside event structure ?

Hi,
I have a problem that my shared variables do not update inside event structure. The program(s) I am trying to get working is seen in the attached screenshot. It works as follows:
0. I start the vi that is unsquared.
1. I write a string to a shared variable using vi in red square. I make sure that its updated using write-wait-read.
2. I run the other vi (blue square), this changes the boolean shared variable.
The unsquared vi has been running the whole time, it has event structure bind to boolean shared variable change (the one in blue vi). After I have runned the blue vi, the unsquared vi should change the indicator values to match the ones in red vi. However I have to start the blue vi multiple times to get it to change, sometimes even 6 times.
Also, when I change the value in red vi to a third value and start blue vi multiple times, the unsquared vi shows all the variables. I.e. I put "cat" to red then start red, put "mouse" to red then start red,... and then start clicking blue... Unsqured shows cat, mouse,..., dog (dog is the default).
How can I force the shared variable to update inside event sructure. I want the current value of the variable, not some historical values.
Attachments:
Screenshot-5.png ‏108 KB

Found the buffering... disabling it solved the problem... thanks.
FYI, there is another solution that I just found out... attached. Adding timeout to the event structure and the variable read outside the event structure... This makes the shared variable strings (one that is read outside and the otherone that is read inside) different.
Could someone explain why the variables are in different state even if they are used in the same place and looped with 10ms intervals?
Juha
Attachments:
Screenshot-6.png ‏110 KB

Exporting Shared Variables to csv

When I try and export SV information to csv, LV (2009, DSC) doesn't seem to recognize any variables that are located within virtual folders in the library. Does anyone know a work-around to get that data tabulated short of cycling through the whole library writing values from SharedVariableIO property nodes to file?
Thanks,
Kyle
CLD using LV, DSC 8.5-2009, RT 8.5
Ghoti!

muks wrote:
Have you seen this?
Yep. That's the problem. The shared variable library I'm working with contains well over 1000 variables that are organized into a few dozen virtual folders within the library. When I use the Export Variables function you linked to, it doesn't "see" any variables in folders, only those in the library root.
CLD using LV, DSC 8.5-2009, RT 8.5
Ghoti!

Error with the Shared Variable Engine

Hi,
I have a problem with the Shared Variable Engine,
A .doc File is attached to this message, decribing the problem with pictures.
I will be glad if anyone can help me.
Sincerely yours
Amitai Abramson
Attachments:
Question.doc ‏819 KB

Hi Amitai,
Good afternoon and I hope your well.
A member of the team from NI Israel contacted me regarding this post.
I want to provide you with extra details on how to resolve your issue - i.e. Repair (Or Re-install) the Shared Variable Engine.
If you use the MsiBlast Tool it will populate a list of all MSI NI Installers. One of these will be NI Variable Engine. On the right-hand side you can the click 'Repair'. I would also Repair the engine support for the versions of LabVIEW you have installed. Please see attachments for MsiBlast and a screenshoot of the MSIBlast screen.
If this doesn't work I would recommend re-installing LabVIEW using the following guide, which I posted on this forum. (second post by me).
Please let me know how you get on,
Kind Regards,
James.
Message Edited by Hillman on 12-03-2008 12:19 PM
Message Edited by Hillman on 12-03-2008 12:19 PM
Kind Regards
James Hillman
Applications Engineer 2008 to 2009 National Instruments UK & Ireland
Loughborough University UK - 2006 to 2011
Remember Kudos those who help!
Attachments:
Repair Shared Variable Engine.JPG ‏97 KB
msiBlast.zip ‏110 KB

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?

Shared variables not working on PC

Can anyone tell from the attached screen shot, why my one shared variable is not working with the labview application I'm running on my PC. I set the variable to 48 (I thought), and yet in the NI Distributed System Manager the value doesn't changed.
Solved!
Go to Solution.
Attachments:
shared_var_not_working.JPG ‏255 KB

Its not likely to be a deadband problem if you haven't touched the settings. I would check it out just in case though. In the project window, right click on the shared variable>>properties and select Update Deadband. See attached image. If it's not this, I shall have to think some more about what else could cause this.
As for ensuring it works when setting it from DSM...from your screenshot you appear to have a VI that writes to the SV. Change the code ore create a new VI so that it reads the SV and then double check that if you change the value in DSM, the VI also reads back the updated value. It may be that the number changes in DSM but does not update the SV in the VI - this would indicate a problem with the shared variable engine or the deployed variable library...Reboot PC and retry... if the problem persists let me know or attach the SV library!
Regards,
Dave
Senior Software Engineer
www.Adansor.com
Attachments:
SV_deadband.PNG ‏8 KB

Deploy shared variable on specific ip

Hi, there is the problem to deploy shared variable on a specific network interface. There are many network interfaces in my computer. If I wan to deploy the variable on the nework interface with the physical address 00:50:56:C0:00:01 and the ip 192.168.117.1 I followed this, but I get that: This is the wlan ip. What is wrong? use Labview 2012 SP1 32bit

What version of LabVIEW are you using? Are you deploying the Shared Variable with LabVIEW Project? Are you running LabVIEW Real-Time? Do you have a Remote declared in the Project? If so, simply put the Shared Variable Library (in Project Explorer) on the Remote and tell it to Deploy -- it should (automatically) go to the right place.
Note that the note you cite is from LabVIEW 8.2.1, which was one of the earliest implementations of Shared Variables. There have been many changes in the last 5-7 years ...
Bob Schor

Slow update of Shared Variables on FP-2015

My application consists of a VI running on an FP-2015 which collects and transmits data from/to various I/O modules (DI-301, aI-111,Do-401 etc.) and passes this data to a Host PC using Shared Variables. It runs embedded on the FP-2015 so that it can react to certain conditions I/O conditions and implement the appropriate safety measures independently of the host pc. When I try to change some of the values of the shared variables from the host PC, it seems to take a long time for them to update on the Fieldpoint controller. For instance, if I try to change the value of a Digital Output on the DO-401 from the Host machine, it can take anywhere from 1-3 seconds before the I/O point actually toggles. I am using an Array of Booleans as the shared variable type. I am pretty sure the code is running at the correct speed at that this delay is caused by the shared variables because if I remove the shared variable and toggle the digital outs from high to low and low to high, they switch at the appropriate rates. Has anyone had any problems with using shared variable on a FP-2015? (The shared variables are hosted on the PC, not the 2015)
Also, I have seen some postings which say the FP-20xx do not have enough memory to run the shared variable server. Should I be OK if the server is running the Host pc? The link below says the shared variable engine will not work properly on the FP-2015 because it does not have enough memory but the second link below says 32mb are required (although 64 are recommended), which the FP-2015 has. Any confirmations whether the shared variables will work properly on the FP-2015. In all, I presently have 6 shared variable, each on being an array with a length of 20 elements.
http://digital.ni.com/public.nsf/allkb/6e37ac5435e44f9f862570d2005fef25
http://zone.ni.com/devzone/cda/tut/p/id/4679
Thanks
Damien

Thanks Tommy, I appreciate the advice. However, I think I will be abandoning the network-published shared variables for now. Before I left the office yesterday, I found the "communication wizard" for the Real-Time module. It allowed me to select my top-level VI and it automatically set up a communication routine to transmit all the controls and indicators from the RT target to the VI running on my host PC. It allowed me to select from multiple communication protocols (I selected TCP) and everything is working well now. I would have liked to use shared variables because they seem to be so simple to use but I do not want to waste time trying to hunt down a problem I may never fix. For now, out with the shared variables, in with TCP.
PS. I didn't change any of my code, (I was using timed loops in case you were wondering), and by changing over to TCP communication all my delay problems were solved. This reinforces my suspicion that the delays were caused by the shared variables.
Damien

Labview is reading zero from shared variable

Hello everyone
-I have a problem in labview shared variable cause it reads only zero value for all inputs and outputs and timers in S-1200 ...etc
but in NI OPC server using quick client it reads the correct value but when adding them in labview project they are not reading the correct value and only retruing zero
any suggestions
Thanks

Hi,
I recently finished the commisioning of the system I started to work upon. Hence the delay to come back to this thread.
During the commissioning of the system, I was concentrating on finalizing the system functionality and was using only the PC#1. Now when all the system functions were finalized, we duplicated the changes to PC#2 and started the operation.
What we observed when the PC#2 was started, was that if we were to open the same HMI page as in PC#1, the operation of the HMI was very sluggish. When we selected a different page for both PC#1 and PC#2, the HMI operation was good, all operations seemed to happen in real time!!
To give a background of the HMI, we have a subpanel to which the desired HMI page/screen is loaded. This loads a VI related to the HMI page.
Here, I am guessing that when I load the same page in both the PCs, the read/write operations to the shared variable(it is the same in both PC, and is deployed in a library on the cRIO) are some how hindered due both PCs trying to access the same network resource from different locations.
Is this guess correct? Any work arounds or solutions? Do I need to post any more information?
Thanks in advance,
Regards

Problem bound variables(shared variable)

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