Siemens SIMATIC S7 Functional Safety Manual page 33

Access protection for the fail-safe CPU
The fail-safe CPU provides five levels of security for restricting access to specific functions.
When you configure the security level and password for a fail-safe CPU, you limit the
functions and memory areas that can be accessed without entering a password.
Each level allows certain functions to be accessible without a password. The default
condition for the fail-safe CPU is to have no restriction and no password-protection. To
restrict access to a fail-safe CPU, you configure the properties of the fail-safe CPU, and
enter and confirm the password.
Table 2- 1 Security levels for the CPU
Security level Access restrictions
Full access incl. fail- Allows full access without password. This is the lowest level of protection for a fail-safe CPU.
safe
(no protection)
Full access Allows full access, except write access to fail-safe blocks.
(no protection)
Password is required for modifying (writing to) fail-safe blocks and for changing the CPU mode
(RUN/STOP).
Read access Allows HMI access and all forms of PLC-to-PLC communications without password protection.
Password is required for modifying (writing to) the CPU and for changing the CPU mode
(RUN/STOP).
HMI access Allows HMI access and all forms of PLC-to-PLC communications without password protection.
Password is required for reading the data in the CPU, for modifying (writing to) the CPU, and for
changing the CPU mode (RUN/STOP).
No access Allows no access without password protection.
(complete protec-
Password is required for HMI access, reading the data in the CPU, for modifying (writing to) the
tion)
CPU, and for changing the CPU mode (RUN/STOP)
Result
The new project has been created and the configuration of the fail-safe CPU is complete.
S7-1200 Functional Safety Manual
Manual, 02/2015, A5E03470344-AA
Getting started
2.2 Configuring
33