Technical data

Basics of Creating Logic Blocks
9.4 Working with Libraries
Programming with STEP 7
Manual, 05/2010, A5E02789666-01 241
10.1.2 Basic Procedure for Creating Logic Blocks
Logic blocks (OBs, FBs, FCs) consist of a variable declaration section, a code section as well as
their properties. When programming, you must edit the following three parts:
• Variable declaration: In the variable declaration you specify the parameters, system attributes
for parameters, and local block-specific variables.
• Code section: In the code section you program the block code to be processed by the
programmable controller. This consists of one or more networks. To create networks you can
use, for example, the programming languages Ladder Logic (LAD), Function Block Diagram
(FBD), or Statement List (STL).
• Block properties: The block properties contain additional information such as a time stamp or
path that is entered by the system. In addition, you can enter your own details such as name,
family, version, and author and you can assign system attributes for blocks.
In principle it does not matter in which order you edit the parts of a logic block. You can, of course,
also correct them and add to them.
Note
If you want to make use of symbols in the symbol table, you should first check that they are
complete and make any necessary corrections.