Logic Stack Overview - Siemens SIMATIC S7 System Manual

Program instructions
7.1 Bit logic
FBD editor input assignment
The editor feature described in the following table is active only if an input stub is selected
and colored red, inside the FBD box cursor.
Input option
Add input
Remove input
Toggle negate input
Toggle immediate input
See also
Bit logic input examples (Page 182)
Logic stack overview (Page 172)
7.1.3

Logic stack overview

The STEP 7-Micro/WIN SMART program compiler uses the logic stack to transform the
graphical I/O networks of LAD and FBD programs into STL (statement list) programs. The
resultant STL program is logically the same as the original LAD or FBD graphical network
and can be executed as a program list. All successfully compiled LAD and FBD programs
have generated the underlying STL program and can be viewed as LAD, FBD, or STL.
For LAD and FBD editing, the STL logic stack instructions are automatically generated and
the programmer does not need to use the logic stack instructions.
You can also create STL programs directly with the STL editor. An STL programmer uses
the logic stack instructions directly. Combination logic can be created in the STL editor that is
too complex to be viewed in the LAD or FBD editor, but may be necessary for special
applications.
All successfully compiled LAD and FBD programs can be viewed in STL, but not all
successfully compiled STL programs can be viewed in LAD or FBD.
172
Place cursor
On box
On box and bottom input
On box and input
On box and input
Tool button
System Manual, V2.3, 07/2017, A5E03822230-AF
Shortcut key
+
-
F11
CTRL F11
S7-200 SMART