Protecting Access To The Cpu Or Code Block Is Easy - Siemens SIMATIC S7-1200 Manual

If the CPU were to detect an event in priority group 3 (such as a time error event), the time-
error OB interrupts the processing of both priority group 1 (such as a program cycle OB) and
priority group 2 (such as a cyclic OB). The CPU executes the time-error OB and then returns
to the execution of the OB that was interrupted, either in priority group 2 (if interrupted) or in
priority group 1.
4.5

Protecting access to the CPU or code block is easy

The CPU provides 3 levels of security for restricting access to specific functions. When you
configure the security level and password for a 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 CPU is to have no restriction and no password-protection. To restrict access
to a CPU, you configure the properties of the CPU and enter the password.
Entering the password over a network does not compromise the password protection for the
CPU. A password-protected CPU allows only one user unrestricted access at a time.
Password protection does not apply to the execution of user program instructions including
communication functions. Entering the correct password provides access to all of the
functions.
PLC-to-PLC communications (using communication instructions in the code blocks) are not
restricted by the security level in the CPU. HMI functionality is also not restricted.
Security level
No protection
Write protection
Read/write protection
Easy Book
Manual, 11/2009, A5E02486774-01
4.5 Protecting access to the CPU or code block is easy
Access restrictions
Allows full access without password-protection.
Allows read-only access to the CPU, HMI access, and PLC-to-PLC
communications without password-protection.
Password is required for modifying (writing to) the CPU and for changing the
CPU mode (RUN/STOP).
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).
PLC concepts made easy
To configure the password, follow these
steps:
1. In the "Device configuration", select the
CPU.
2. In the inspector window, select the
"Properties" tab.
3. Select the "Protection" property to
select the protection level and to enter a
password.
The password is case sensitive.
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