cRIO 9002 : "Bind to Source" required for network-published shared variables?

[Penny]

Hi,

We have a cRIO-9002 with a PC on the same subnet, and
would like to host the library of shared variables on the cRIO.
Our question is:  If we make the shared variables "network
published", should that be sufficient to make them readable/writable
for the PC and the cRIO?  Or, do we also need to select the
"bind to source" box, and choose a source explicitly?

Note:  We are "autodeploying" the library on the cRIO, and can
presumably "deploy" the shared variable library from the cRIO
to the PC at the beginning of the host.vi .

Thanks!
-Penny

[MattP]

Hi Penny,

If all you're looking to do is be able to share data between the cRIO and the PC, then setting up the variables as 'network published' will do so.  If you wanted the shared variable to also be bound to a process item (for example, to communicate to a PLC via Modbus), then you could use the 'Bind to source' option as well.  For simple communication, this is not necessary.

When using network-published shared variable, the variable must be hosted by one machine which acts as a server for that variable, publishing the data that other computers can then read from.  Before we can publish the data, the variable must be deployed on the host machine - essentially this is what tells the server to begin sending and receiving data for that variable.  You only need to deploy a variable in one location, since once it has been published, other machines then have access to that data.  So in your case, when you deploy the variables on the cRIO, your host machine can then connect to the cRIO and find the correct data.  If you're doing your development with the LabVIEW Project, then this communication will be transparent to you.

For some more background on how shared variables work, I'd recommend the Using the LabVIEW Shared Variable white paper - this is an excellent resource for understanding the underlying principles involved, and will shed some light on what the various options mean.

[Penny]

OK thanks!

-Penny