Dear Pierre,

I have noticed that PSOM will create a file named '1.txt' in the current path of matlab when 'background' mode is used (the code is in the psom_run_script.m). 
However, if we don't write permission in the current path, then the error occurred.
In fact, this is very common when PANDA used.

I recommend that this file can be stored in the personal fold (/home/username) of users in Linux.
Because we can ensure that the user have the write permission for the fold /home/username.

Best wishes

Zaixu