Technical data

Creating Blocks and Libraries
9.3 Creating Blocks
Programming with STEP 7
228 Manual, 05/2010, A5E02789666-01
Keyword / Property Meaning Example
[UNLINKED] for DBs only! Data blocks with the UNLINKED property
are only stored in the load memory. They
take up no space in the working memory
and are not linked to the program. They
cannot be accessed with MC7
commands. Depending on the specific
CPU, the contents of such a DB can be
transferred to the working memory only
with SFC 20 BLKMOV or SFC 83
READ_DBL.
[Non-Retain] Data blocks with this attribute are reset
to the load values after every power OFF
and power ON and after every
STOP-RUN transition of the CPU.
[READ_ONLY] for DBs only Write protection for data blocks; its data
can only be read and cannot be changed
READ_ONLY
Read-only block A copy of a block that is stored in
read-only status for reference purposes.
This property can only be assigned in
the program editor by selecting File >
Store Read-Only menu command.
The block protection KNOW_HOW_PROTECT has the following consequences:
• If you want to view a compiled block at a later stage in the incremental STL, FBD, or Ladder
editors, the code section of the block cannot be displayed.
• The variable declaration table for the block displays only the variables of the declaration types
var_in, var_out, and var_in_out. The variables of the declaration types var_stat and var_temp
remain hidden.