Using shared variables between different verions of labview

[RMaso]

Hello,

I am investigating the use of shared variables between two different versions of LabVIEW. We have a system made of 2 PXI's and a single PC. We're currently updating the code on the PXI's to be 2014, but the PC is still running 8.2.1. We now have a need for an ARINC-429 card that only runs 2009+, which is why we're updating. Initial tests show that the shared variables don't communicate between the two. I believe the reason may be that the PXI is running the 2014 version of the shared variable engine, while the PC is running 8.2.1, but I'm not sure if this is exactly the reason it doesn't work. Is there a way to communicate between two different versions of LabVIEW with Shared Variables?

Thanks!

[Bob_Schor]

Wow!  I'm willing to wager far more than my usual dime that there's no way this will work!  Heck, I can't even get my LabVIEW 2014 Real-Time project to run on a PXI that was build with LabVIEW 2012 software unless I rebuild the PXI to be exactly the same LabVIEW version as the code being developed!  [If I'm wrong, I'll stake you to a beer at NI Week ...]

BS

[RMaso]

Well, that makes sense, on your PXI, because of the run-time engine version. It sounds like you're running a 2014 program on the 2012 RTE? I wouldn't think that would work either.

On the issue I posted though, I was able to get the shared variables to communicate between 2 laptops, one with 2014 and the other with 821. So there may be hope. It appears that the version of the shared variable engine may not matter. I may have had another issue that was preventing the PXI and PC from communicating. 

[mikeporter]

I'm with BS -- I mean Bob -- 😊 I doubt that cross versions, especially that far apart, will work. How many shared variables are we talking about here? There are alternatives that I know will work, but it will require modifying existing code.

Mike...

PS: in case some strange characters appear above, that is my phone's attempt to insert a smiley face...

[RMaso]

There is a significant number of shared variables... about 75; clusters, doubles, arrays of doubles, strings, all the fun things. Like I said above though, I'm getting all of them to talk between 2014 and 8.2.1 with 2 different laptops connected to each other. Next step is to try the code with the PXI and a laptop.

I do agree that it seems like an insurmountable task with 821 being so dated. But here's hoping!

[RMaso]

Update:

I took the same code that I was running on the 2014 Laptop and put into a 2014 configured PXI. Naturally, everything communicates between the PXI and the 2014 laptop. When I connect the 821 laptop to the PXI, the shared variables do not connect (red triangles) or update. Also, the shared variable manager with 821 does not connect or update to the PXI, but it can see what variables make up the library being broadcast. 

Any ideas? Is there some other software I need to install on the PXI to get the communication to work between versions?

[RMaso · Accepted solution]

SOLUTION

There are two key components in the software install process that are critical to getting the PXI to communicate with a different version of LabVIEW: Variable Legacy Protocol Support and Variable Legacy Server Support. The first, Protocol Support, was installed automatically through the selection of other components (although I'm not sure which triggered its install). The second was nested inside the Protocol, but wasn't automatically selected. 

The Protocol allows the 2014 PXI to communicate to shared variables hosted by 8.6 or earlier devices, while the Server allows pre-2009 devices to communicate to shared variables hosted on the 2014 PXI (which was the original problem)!

[mikeporter]

Excellent! And kudos to you for coming back and documenting what you found. Future generations may not, "rise up and call you blessed" but be assured you have saved somebody down the line a bunch of time.

Mike...

[Bob_Schor]

I owe RMaso a beer!  Look me up if you come to NIWeek 2015 ...

Bob Schor