99BProgramming concepts
6.6 Protection
S7-1200 Programmable controller
154
System Manual, 11/2011, A5E02486680-05
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.
Table 6- 4
Security levels for the CPU
Security level
Access restrictions
No protection
Allows full access without password-protection.
Write 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
(RUN/STOP).
Read/write protection
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).
6.6.2
Know-how protection
Know-how protection allows you to prevent one or more code blocks (OB, FB, FC, or DB) in
your program from unauthorized access. You create a password to limit access to the code
block. The password-protection prevents unauthorized reading or modification of the code
block. Without the password, you can read only the following information about the code
block:
●
Block title, block comment, and block properties
●
Transfer parameters (IN, OUT, IN_OUT, Return)
●
Call structure of the program
●
Global tags in the cross references (without information on the point of use), but local
tags are hidden
When you configure a block for "know-how" protection, the code within the block cannot be
accessed except after entering the password.
Use the "Properties" task card of the code block to configure the know-how protection for
that block. After opening the code block, select "Protection" from Properties.