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Do away with DSC run-time license for getting shared variable value change events

Status: New

 Getting a value change event on a shared variables seems to me like something that ought to be expected "out of the box" in LabVIEW.  Polling shared variables for changes is taxing on resources, and such an architecture is generally frowned upon by NI and the LabVIEW community for things like front panel interactions and the like.  Why, then, should we expect to pay extra to deploy applications which such an architecture for interacting with shared variables?


I completely understand the extra license for the DSC run-time, as there are numerous other terrific tools included.  It just seems to me that the SV value change events are one thing that should be freely available for deployment to everyone already paying for the application builder.






Thanks for your comment.  One of the main reasons I recommend NI products to my management is the support that NI provides to its customers, as evidenced by your comment here. 


From my internet and personal discussions with other engineers I know I am not alone in my appreciation of this feature or my consternation at the barriers to using it.


Unlike, say, FPGA, it is hard to get management to understand why thy should pay so much for a module when we really don't need most of it.  What usually happens is that we don't buy DSC, and if the SV events feature is really critical (which it sometimes is for distributed applications) it has even led to us not using NI products for tthat particular solution at all. If NI feels that it must sell SVEs as a seperate product, I am sure that I could get my management to pay $100 for an SVE module rather than over a thousand for the DSC, for which a runtime also has to be purchased for every fielded system. That is often a show-stopper in my projects, even with me on your side as an NI evangelist who positively represents NI products at meetings.


Thanks for your attention.


This would be a really nice improvement for getting rid of the polling for value changes in the shared variable. The DSC license is also out of scope for our use case, espacially considering that this would be the single use case for the features provided by DSC.


I just ran into this issue again for the 4th or 5th time in 5 years.  I urge NI to somehow make the network shared variable events available to labview users without DSC.


My team has encountered this and related issues when attempting to use LabVIEW for OPC communication.  Frankly, Data Sockets are a really poor choice in almost all circumstances based upon our experience.  When OPC is required, we're beginning to look to other programming languages and toolkits, as LabVIEW is simply too much of a hassle.  It's a shame, as it seems to me an industry standard network protocol for exchanging process control data would be right up LabVIEW's alley.. DSC is still a ridiculous expense for something so easily handled in other languages.

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I use datasockets and have no problems. The ability to not poll for changes is a must. No extra charge for a DSC module required.


I understand that this is an Idea Exchange and not a support forum, but since people were discussing so much about the DSC module and value change notifications I couldn't help it.  I had the fortune to work with Shared Variable Value change notifications in DSC Module. But the event keeps on firing to all changes irrespective of what is defined. It apparently made my interface stuck and caused me a lot of troubles. If my memory is right, I think I have read somewhere that the value change notification would fire for all changes if the datatype used is Boolean or Numeric. I now doubt what is the use of that vi. Even the example that came with Labview has the same issue.

I use labview 2016 by the way. If I get the link I will post it.


Update: I found the NI knowledge base link here. Seems like there are a lot of other datatypes too. I would suggest using the good old TCP/IP for communication. Alarms and Event generation would be a bit difficult though (or so I think). DSC had a lot of features which literally made alarm generation a piece of cake.