Siemens SIMATIC STEP 7 V5.2 Getting Started page 24

Creating a Program in OB1
Copying the Symbol Table and Opening OB1
In STEP 7, OB1 is processed cyclically by the CPU. The CPU reads line by line and
executes the program commands. When the CPU returns to the first program line, it has
completed exactly one cycle. The time required for this is known as the scan cycle time.
Depending on which programming language you have selected, continue reading in either
Section 4.2 for programming in Ladder Logic, Section 4.3 for Statement List, or Section 4.4
for Function Block Diagram.
You can find more information under Help > Contents
in the topics "Programming Blocks" and "Creating
Blocks and Libraries."
4-2
If necessary, open your "Getting
Started" project. To do this, click the
Open button in the toolbar, select the
"Getting Started" project you created,
and confirm with OK.
Depending on which programming
language you have decided to use, in
the "Sample projects" tab open one of
the following projects as well:
•
ZEn01_05_STEP7__LAD_1-9
•
ZEn01_01_STEP7__STL_1-9
or
•
ZEn01_03_STEP7__FDB_1-9
Here you can see all three sample
projects displayed.
Navigate in the "ZEn01_XXX" until you
reach the Symbols component and
copy this by dragging and dropping it
to the S7 Program folder in your
project window "Getting Started."
Then close the window "ZEn01_XXX".
Drag and drop means that you click any object
with the mouse and move it whilst keeping the
mouse button depressed. When you release the
mouse button, the object is pasted at the selected
position.
Double-click OB1 in the "Getting
Started" project. The LAD/STL/FBD
program window is opened.
STEP 7 Getting Started
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