Shared Variable Values after PC rebooting

[Kursant]

Hi.

I use shared variables on several projects on different nodes. On some of them, after rebooting the OS, the variables restore their value (as it should be), on others this does not happen. I use Windows 10 and approximately the same setting. Does anyone know where you can search in the OS settings or labview to get predicted DSC behavior after rebooting the OS.

Sincerely, Vitaly.

[RavensFan]

Are any of the shared variables linked or aliased to other variables in other libraries on other PC's?

[Kursant]

One "bad" node has 4 SVs aliased to another node. To test we removed these SVs manually (using System Manager) from main process and then rebooted the PC. After rebooting the problem with resetting SVs to Not Knowing values remains. But some SV (double) have restored to the values of one day ago (as operator said). Because of resetting boolean SVs to Not Knowing values, rebooting process couses switching off mains, working devices and so on, it is very important for us to retrieve the last good (working) values after rebooting. Is there a place on disk, or file(s) where LabVIEW stores its runtime database with SVs?

[RavensFan]

Not that I'm aware of.

If "t is very important for us to retrieve the last good (working) values after rebooting."  then you should build that into the program.  At the beginning of your program, set your shared variables to known safe states.  If needed, save the values to your own configuration file whenever they change.  On startup of the VI, read that file and set the shared variables to those values.

Shared variables can be tricky when you get to aliasing because you can make a chain of variables that are based on different libraries on different PC's.  You can set the variables to be read only, write only, or read-write.  You need to make sure libraries are deployed.  Change one aspect of any of these and you can have quite a few combinations of conditions where some times things  work fine and other times they don't.

[Kursant]

Thank you for your help. We considered such a solution. But since the LabVIEW claims that the variables should be preserved after a reboot, we want to understand the true causes of the problem of the impossibility of restoring values ​​in order to eliminate it. After all, on some PCs, everything works well. In our system, there are about 9000 variables on 4 PCs. We use about 20 programs (drivers, HMIs) working with shared variables. For us, in a tuned and running system (for example, vacuum maintanance), the last (combination of) values before rebooting are safe values. The problem is the spontaneous reboot of the os, for example, when updating windows. We would like to use the internal mechanism for saving and restoring variables, implemented in a LabVIEW, rather than periodically saving 9000 variables to disk and an additional recovery service, which will reduce system performance.

https://www.researchgate.net/publication/320517991_USING_LABVIEW_TO_BUILD_DISTRIBUTED_CONTROL_SYSTEM...