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.