Protection; Access Protection For The Cpu - Siemens S7-1200 System Manual

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Programming concepts

6.6 Protection

Instructions that take more than one scan to execute often provide a Busy parameter (Bool)

to signal that the instruction is active but has not completed execution. These instructions

often also provide a Done parameter (Bool) and an Error parameter (Bool). Done signals that

the instruction was completed without error, and Error signals that the instruction was

completed with an error condition.

● When Busy = 1 (or TRUE), ENO = 1 (or TRUE).

● When Done = 1 (or TRUE), ENO = 1 (or TRUE).

● When Error = 1 (or TRUE), ENO = 0 (or FALSE).

The CPU provides four 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. 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 at that level.

PLC-to-PLC communications (using communication instructions in the code blocks) are not

restricted by the security level in the CPU.

Security levels for the CPU

Security level

Full access (no

Access restrictions

Allows full access without password protection.

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

S7-1200 Programmable controller

System Manual, 03/2014, A5E02486680-AG