99BProgramming concepts
6.5 Programming language
S7-1200 Programmable controller
System Manual, 11/2011, A5E02486680-05
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Consider the following rules when creating a LAD network:
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You cannot create a branch that could result in a power flow in the reverse direction.
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You cannot create a branch that would cause a short circuit.
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6.5.2
Function Block Diagram (FBD)
Like LAD, FBD is also a graphical programming language. The representation of the logic is
based on the graphical logic symbols used in Boolean algebra.
To create the logic for complex operations,
insert parallel branches between the boxes.
Mathematical functions and other complex functions can be represented directly in
conjunction with the logic boxes.
STEP 7 does not limit the number of instructions (rows and columns) in an FBD network.
6.5.3
SCL
Structured Control Language (SCL) is a high-level, PASCAL-based programming language
for the SIMATIC S7 CPUs. SCL supports the block structure of STEP 7 (Page 138). You can
also include program blocks written in SCL with program blocks written in LAD and FBD.
