"shared variable is not allowed" error on sbRIO

[InfiniteNothing]

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Ravens Fan wrote:

One of the things mentioned in that error message was "change the type of the variable."  That is a rather unclear message.  It should at least tell you what is wrong with the "current type".

I did notice that you had logging turned on for that SV (which is a DSC function that got me talking about DSC functions on the cFP target).  I would try turning that off.  Perhaps play around with network settings, buffering settings, anything else that might be settable.  See if any of those changes make the error go away and you stumble on whatever it considers the "correct type".  That might give a clue as to what is going wrong.

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Turning off all the DSC features (logging, the alarm, etc) makes it work but those are important features for me.

[Spex]

InfiniteNothing,

We have left out an important question thus far, which version of LabVIEW are you using?

Also, I don't have DSC installed on the laptop I'm using, so I haven't been able to take  a look at your example code yet.   It's been a while since I've worked heavily with DSC (since I've move to focus on Single-Board RIO), but I think my previous post is accurate.  

I'm trying to get my hands on a machine with Real-Time and DSC installed so I can take a look at your code later today.  In the mean time, hopefully an Applications Engineer will look into it as well and chip in their observations/recommendations.

Say "Hi!" to M. Slaughter and J. Spinozzi at Cyth for me...

Cheers,

[jkurtw]

Strange... on first inspection this looks like a bug.

This is not an issue with CompactRIO. I just tried it with a 9074.

Maybe it is disabled on sbRIO for a good reason I don't know of, but I believe the functionality is there. The sbRIO context is just not letting you place that node on the diagram.

Try using the programmatic read like this:

 

LabVIEW can't break the VI when you use this read, so at least you can check to see if it works while running.

Kurt 

[Spex]

I agree this looks like a bug.  We'll check in with the developers to see if there is any technical reason why DSC variables are not allowed on Single-Board RIO, and what they suggest for work arounds.  In the meantime, I think we've identified a couple work arounds.  

I tested the method Kurt suggests, and it does work, but you will need to replace the "localhost" address with the IP address or machine name of the host PC that is hosting the variables. 

I also tested binding shared variables that are deployed local to the Single-Board RIO to variables hosted on the PC.  That method also worked.  

To bind a share RIO, check the box on the variable page for Enable Aliasing.  Then Browse the project variable you want to bind to, and click OK.  For large applications, you can also use the multiple variable editor to create all your Single-Board RIO variables and bind them to the host URLs, or Export your shared variable list to Excel, modify them for the Single-Board RIO target, then re-import.(thjis sounds a lot more complicated than it is... 🙂 )

Cheers,

[InfiniteNothing]

When I try the aliasing I get this error from rt.vi: -1950679023 

I can't try the "Read Variable" vi (nice snippet) because currently I'm using 8.6 though I'll upgrade if I see no other option. If you could, check my attachment, to make sure I didn't mess anything up.

Message Edited by InfiniteNothing on 09-15-2009 05:54 PM

[jkurtw]

You can also use a datasocket read VI to read your NSVs.

I believe the URL will be psp://computername/library/variable 

If you look at the Help for datasocket you can find the various data sources it can read from and their URL syntax.

I'll let you know if I get a chance to try your code today.

Kurt  

[Spex]

You mentioned LabVIEW 8.6, but does it happen to be 8.6.1?  I did a quick search on the error message you are receiving, and several of the results were related to a bug in 8.6.1 shared variables which is discussed, and patched in the first two links below:

Shared Variable Error -1950679023 in LabVIEW 8.6.1 Forum Post

Patch for deployed shared variables on LabVIEW Base Development System 8.6.1 - Windows 2000/Vista x6...

Sounds like this error can sometimes also be attributed to the Windows Firewall.

 Cheers,

[InfiniteNothing]

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Spex wrote:

You mentioned LabVIEW 8.6, but does it happen to be 8.6.1?  I did a quick search on the error message you are receiving, and several of the results were related to a bug in 8.6.1 shared variables which is discussed, and patched in the first two links below:

Shared Variable Error -1950679023 in LabVIEW 8.6.1 Forum Post

Patch for deployed shared variables on LabVIEW Base Development System 8.6.1 - Windows 2000/Vista x6...

Sounds like this error can sometimes also be attributed to the Windows Firewall.

 Cheers,

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Yes I'm using 8.6.1. I will try the fix

[InfiniteNothing]

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jkurtw wrote:

You can also use a datasocket read VI to read your NSVs.

I believe the URL will be psp://computername/library/variable 

If you look at the Help for datasocket you can find the various data sources it can read from and their URL syntax.

I'll let you know if I get a chance to try your code today.

Kurt  

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Hmm, I used datasocket with SVs early on in the project. I can't remember why I dropped them. They seem to work well with a 0 ms timeout.