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[CR] Variant Repository

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  • 2 weeks later...

I assume you meant XNodes not XControls.  After an XNode is interacted with it will make the VI using scripting.  And so in an EXE this VI should be what is used, and therefore no XNodes exist in a EXE, only the VIs they make.  Besides NI uses XNodes all the time.  A common one is the match regular expression so you shouldn't have any issues.


...that being said I just tried to make an EXE with my VR package and it fails...so yeah I need to look into that.


EDIT:  It looks like this does work.  I've been making a few changes since this release and something in that version broke which doesn't allow EXEs to be made.  This version works fine.


Double EDIT:  So it looks like from source works, from the files on the palette it doesn't so something got messed up in the package making process.  But this shows that that XNodes themselves can be in EXEs.


Tripple EDIT: Okay so I found the issue was with the Post-Install VI that was being used in the package making process.  It wasn't all that necessary and I got rid of it and uploaded a new version that I have built into EXE without a problem.  The new version uses the UpdateData ability so older copies of the XNode should be replaced with newer ones after opening a VI that used the older version.

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  • 5 months later...

Some have asked for the Variant Repository VIs to be available as non-XNodes.  So I wrote some scripting code to make polymorphic instances, edit VI icons, and make the polymorphic VIs.  But what I hope this illustrates is just how useful XNodes are.  


The Non-XNodes version is 252 VIs and one control.  That's a lot of VIs to have to load into memory when using these polymorphic instances.  That's 60 normal VIs inside each of the 4 polymorphic VIs.  And it doesn't even support all of the features the XNode counter parts do.  


From a reusability stand point polymorphic VIs have many things that make using and maintaining them difficult.  From the number of files loaded, to custom help, icons, and terminals from each instance, along with supporting more types than the polymorphic could.  Don't get me started on when a bug is found and it isn't something you can easily fix with scripting.  So then you need to open up each of the polymorphic types and make changes to each one.  Oh and ever try to use the polymorphic editor with 60 instances?  Yeah I've stopped trying and use a combination of tools so I never need to.


Some day, hopefully NI will be able to invest the time needed to make XNodes an official feature.  But until then I'll likely need to support many polymorphic types, when XNodes aren't trusted.

Variant Repository Non-XNode.zip

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  • 1 year later...


Great tool. Considering using it for sharing data between vision functions in a plugin based architecture. Passing the variant repo reference as a DVR to the modules. Though I need some more datatypes Specifically from VDM (point, line, reference coordinate system, ROI etc.). Anyway to do that ?



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Very nice indeed  :beer_mug:


I am thinking about using this in a project where I have to interface with some external equipment via OPC-UA and some other custom protocol. I have lots of "variables" (tags) and want to experiment how things can be done as much as possible by just using a channel name in my code rather than individual element access.


Anybody given any thought as to how best to share the variant between processes? Lots of options here, as Kahrma mentioned perhaps a good technique is a DVR? 

Edited by Neil Pate
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It wouldn't be hard to change the XNode to take a DVR of a variant rather than the variant itself. I did something similar so it would take an object and it was a lot easier than I thought it would be.


For OPC UA in the past I've used the CVT and just made a small process which reads each OPC UA data value and copies it into the CVT. Then you can define groups for each of your tags and read data by group.


NI made something very similar recently, although not as nice as this variant repo. The advantages though are that it has some metadata (last update timestamp, whether or not the value is valid, and then another variant for metadata):


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Yeah I have other issues with the CVT, like performance.  And when writing a messaging library that is uses a wrapper constantly for variant data, I wanted it to be light weight, and generally I didn't find a wrapper for a look up table that wasn't better when it comes to performance than Variant Attributes.

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One of my issues with the CVT is that as it stands everything is a double right?

No, numerics, bools, strings, and arrays of the same.


Yeah I have other issues with the CVT, like performance.  And when writing a messaging library that is uses a wrapper constantly for variant data, I wanted it to be light weight, and generally I didn't find a wrapper for a look up table that wasn't better when it comes to performance than Variant Attributes.

Doesn't sound like you're using it for an appropriate use case -- if every access is completely dynamic then yes there is no point to it vs a lookup. where it shines is neil's use where there are a fixed set of tags which you want to share globally but, being fixed, you can cache the lookups for. An equivalent but sometimes slower implementation would be using your variant repo where every contained value is a dvr or queue or notifier. The dvrs can be slower if, as in the opc ua situation, you want to access a large number of elements in one go. 

Edited by smithd
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Doesn't sound like you're using it for an appropriate use case -- if every access is completely dynamic then yes there is no point to it vs a lookup. 

It sorta is dynamic.  Actors can unregister or register to new events at run-time, but in practice is never really needs to.  And the messaging structure is based on user events, and you can't register for an array of user events, unless each of the data types of each event are the same, which is where I used the variant as the data type.  Also there are times when I might only want some information from the variant, and I don't pull out all of the payload, something like meta data instead, and I believe this is most efficient with a variant attribute, where you don't have to read everything.

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  • 2 weeks later...

Well that is concerning for sure.  Unfortunately I don't have 2015 SP1 yet, but this might be as good of reason as any to start the long download process of that whole software suite.  But the fact that this happens on the save makes me even more confused.  If it were on the wire operation then I could do some debugging and look into the VIs that get ran, when the wire operation takes place.  But the fact that the wire operation works just fine, and it is just on the save, makes me think it might be something more difficult to troubleshoot and resolve.  Well I guess I'd send the report to NI...and hope for some support.

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I can't really narrow down what causes it.  But it seems like if you copy the read var xnode from the existing diagram and wire the same cluster type to it, its fine.  But if you select a new instance of the xnode from the addons pallette and place it on the diagram and wire to the same constant, then save it crashes.  I don't know if that helps narrow it down to an ability or not.  Also it doesn't seem to happen with the string data type.  So far I have just seen it on clusters.  It may be a labview bug and be unrelated to the xnode.  I have no idea.

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  • 4 weeks later...

Well you shouldn't need a license to edit them, they are just XML and can be read in a text editor.  I haven't yet figured out how to link to a specific post in this new format, but the New XNode Editor 2012.zip I posted here should allow you to look at all the abilities in an XNode and do some basic editing like add other abilities.


EDIT:  Oh I figured it out, this is the actual post.

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I still must be doing something stupid, how do I actually made modifications to an existing (or a copy of) XNode?

I can open the ability VIs fine, but they are locked.

All I want to do is try and modify your XNode to make it accept a DVR to a variant rather than a plain variant. This is my first real foray into XNodes, so I am probably missing something obvious even though I have tried to read as much of the literature as I can.

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  • 2 weeks later...
On 4/23/2016 at 9:51 AM, Neil Pate said:

I can open the ability VIs fine, but they are locked.

This is probably because a copy of the XNode is in memory.  Just like an XControl you can't edit an XNode while it is in memory in another instance.  At least I think that is what is going on here.  They shouldn't be locked.

On 4/23/2016 at 9:51 AM, Neil Pate said:

All I want to do is try and modify your XNode to make it accept a DVR to a variant rather than a plain variant. 

Neat addition feel free to post your contribution if you get anything working.

On 4/24/2016 at 4:49 AM, LogMAN said:

Wow, new Lava embeds videos now :o

Super cool BTW.

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  • 4 months later...

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