I've read the articles you proposed. To the approach with the data persistence, I have doubts in my case. This seems to be more a storage for configuration files. Updating a file every 5 ms seems to me not to be a good idea as it might harm the hard disk on long term. This is why I want to use the NVRAM of the controller and not the file system. As far as I understood, the way to use the NVRAM is to use the data layer with RT access. I've already tried the SDK example for shared memory and copied the relevant code to my project. This worked as long as I used the non-retain shared memory. As soon as I switched to shared retain memory, I got the error message "DL_CLIENT_NOT_CONNECTED". In the meantime, I've found out that for some reason the shared retain memory doesn't work if you run the program in the app build environment, using the COREvirtual datalayer. If you use the datalayer broker of the app build environment, it seems to work. At least, it doesn't generate any error messages. But you don't see the data layer in your browser. If you create a snap and let it run in the COREvirtual, it works as well. So especially the retain memory seems to have the restriction that it can only be used from the own controller. In the end, it was a lot of trial and error, because of using the app build environment in combination with the COREvirtual. But finally, using just the COREvirtual, it worked.
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