There is logi.CAD 3 FBD-Light in the store. Do I need this for the development of commercial programs in ST or does it only provide me with FBS in addition? What are the differences to the normal logi.cad version?
This software is only used to edit programs via Function Block Diagram, so no, for the development of commercial programs in ST you do not need this software, it is an optimal extension. Thus your question about differences is also clarified - there is only one Logi.CAD version plus this optimal extension.
What license do I need and what is the difference between single and multicore license?
The license is due per device.
Multi Task means that the runtime runs on multiple processor cores.
Can the source code of a program be recovered by downloading it?
No, an installed program is available in binary form on the device.
https://revolution.kunbus.de/forum/viewtopic.php?f=12&t=2808
I am unable to connect to the device after an update of my code.
Basically logi.CAD 3 or the RTS will intercept a problem occurring at runtime (e.g. division by 0), unless it happens in a C block written by yourself. However, if you program "an endless loop" in the ST code - this will not be intercepted.You can then connect to the RevPi with tools like "Putty" and delete the file "RTSCode.so" there and restart the RTS.