Technical data

Establishing an Online Connection and Making CPU Settings
18.1 Establishing Online Connections
Programming with STEP 7
Manual, 05/2010, A5E02789666-01 405
18.1.4 Password Protection for Access to Programmable Controllers
Using password protection you can:
• Protect the user program in the CPU and its data from unauthorized changes (write protection)
• Protect the programming know-how in your user program (read protection)
• Prevent online functions that would interfere with the process
You can only protect a module or the content of a MMC (e.g. for a CPU 31xC) with a password if
the module supports this function.
If you want to protect a module or the content of a MMC with a password, you must define the
protection level and set the password in the course of assigning the module parameters and then
download the changed parameters to the module.
If you enable the access protection on a CPU (integrated function as of STEP 7 V4.02), please
remember the following: If, following enabling of this function, you attempt to edit the CPU with a
version lower than STEP 7 V4.02, messages will be displayed indicating that this CPU is password
protected (for example "protection level not reached", "...could not be loaded", "...could not be
opened").
Note
If your CPU is set to protection level 1 and your CPU makes SFC 109 "PROTECT" available, you can
switch between protection levels 1 and 2 with this SFC.
If you need to enter a password to execute an online function or access the content of a MMC, the
"Enter Password" dialog box is displayed. If you enter the correct password, you are given access
rights to modules for which a particular protection level was set during parameter assignment. You
can then establish online connections to the protected module and execute the online functions
belonging to that protection level.