Cause : ACX: Writing to the parameter back-up file was unsuccessful - comes when riting to at least one parameter back-up file PSxxxyyy. in the non-volatile memory was unsuccessful.

- In the directory /USER/SINAMICS/DATA/ at least one parameter back-up file PSxxxyyy. has the "read only" file
attribute and cannot be overwritten.

- There is not sufficient free memory space available.

- The non-volatile memory is defective and cannot be written to.

check the file attribute of the files (PSxxxyyy., CAxxxyyy., CCxxxyyy.***) and, if required, change from "read only" to "writeable".

- check the free memory space in the non-volatile memory. Approx. 80 kbyte of free memory space is required for every drive object in the system.

- replace the memory card or Control Unit.