Using shared variables to communicate between two myRIOs.

[SHalim]

Hey all,

I have been trying unsuccessfully to send data between two VIs on two separate myRIOs using a shared variable. I created the library with the shared variable (ballPosArray) in the myRIO that writes data to it. I can get the data when using the variable in other VIs on the same myRIO or on VIs on the computer (testSignalComputer.vi). However, I can't read the data from the variable in VIs on the second myRIO (testSignalRio.vi). I tried accessing it by just dragging it to the Vi first. Then I tried creating a separate library and variable on the second myRIO and binding it to the original shared variable (PSP URL) but I get a 'process specified in the binding URL does not exist' error. I have gone through the threads containing similar issues, but can't seem to get it to work.

Any help will be greatly appreciated!

Thanks,

Sanjid

[AGJ_CR]

Hi Sanjid,

Welcome to our Forums!

Does it also happen if you try to do the opposite? With this I mean hosting the variable on the second myRIO and accessing it from the first one or the host PC.

Regards,

Andres G.

NI

[AGJ_CR]

Sanjid,

Do you get any errors when trying to access the variable from the second myRIO?

 In the case that you don’t have it, you can wire an indicator to the error output of the shared variable to see if something weird shows there when reading.

Andres G.

NI

[AGJ_CR]

Sanjid,

Do you get any errors when trying to access the variable from the second myRIO?

 In the case that you don’t have it, you can wire an indicator to the error output of the shared variable to see if something weird shows there when reading.

Andres G.

NI

[SHalim]

Hey Andres,

Thank you for your response.

Firstly, I do get an error when trying to access from the second myRIO :

    Error -1950679023 occurred at Shared Variable in Rio2_Rio1Read.vi

    Possible reason(s):

    LabVIEW:  (Hex 0x8BBB0011) The process specified in the binding URL does not exist. Ensure that all shared variables are deployed and the variable identifier URL is correct.

I did deploy the libraries before running the VIs.

When hosting a variable on the second myRIO, I can read it from the computer and other VIs on that myRIO, but not on the first myRIO. Interestingly, when I try to bind a variable on the first RIO to one hosted on the second using PSP URL, the library and the variable on the second myRIO (the host) does not show up when I browse for variables. This is not the case when I am going the other way.

I am not sure what the difference in between binding to PSP URL vs Project variable, and I tried the latter as well. I can access the second myRIO variable from the first if I select project variable when binding, but I get the same error as earlier.

Hope this is not too confusing.

Thanks,
Sanjid 

[AGJ_CR]

Hi Sanjid,

That’s certainly unexpected.

Are you able to access these variables from the Distributed System Manager on your Windows machine with no errors?

Have you reproduced this same behavior with another project? Preferable a simple project with a simple variable and one VI for each system (host, myRIO1 and myRIO2). With this we can isolate if the issue is related with the current code.

If nothing of this gives different results, we might want to try reinstalling the Network Variable Engine on the myRIO devices.

Regards,

Andres G.

NI