Specifications

Basic Concepts for Programming an S7-200 CPU
4-9
S7-200 Programmable Controller System Manual
C79000-G7076-C233-01
Function Block Diagram Editor
The STEP 7-Micro/WIN 32 Function Block Diagram (FBD) editor allows you to
view the instructions as logic boxes that resemble common logic gate diagrams.
There are no contacts and coils as found in the LAD editor, but there are
equivalent instructions that appear as box instructions. The program logic is
derived from the connections between these box instructions. That is, the output
from one instruction (such as an AND box) can be used to enable another
instruction (such as a timer) to create the necessary control logic. This connection
concept allows you to solve a wide variety of logic problems.
Figure 4-6 shows an example of a program created with the Function Block
Diagram editor.
AND
V50.0
TON
AC0
IN
I2.1
PT
T33
Figure 4-6 Example of FBD Program
The main points to consider when you select the FBD editor are:
 The graphical logic gate style of representation is good for following program
flow.
 The FBD editor can be used with both the SIMATIC and IEC 1131-3 instruction
sets.
 You can always use the STL editor to display a program created with the
SIMATIC FBD editor.