Siemens TOA portal module 040-020 User Manual
Industry Sector, IA&DT
SCE Training Curriculum
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TIA Portal Module 040-020, Edition 03/2013
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SCE_EN_040-020_R1209_Startup Programming in High-Level Languages with S7-SCL and SIMATIC S7-300
4.3
Program structure
Program execution is written in what are referred to as blocks. The Main [OB1] organization block is
provided as default. This block represents the interface to the CPU operating system and is
automatically called and cyclically processed by this operating system.
From this organization block, additional blocks can be called in turn for structured programming, such as
the function calculate_tankcontent [FC140]
This function is used to break an overall task down into subtasks. These can then be solved more easily
and tested in their functionality.
Structure of the tank content sample task
Main organization
block [OB1]
Block called cyclically
by the operating
system. Here is the
call of the function
calculate_tankcontent
[FC140]
block [OB1]
Block called cyclically
by the operating
system. Here is the
call of the function
calculate_tankcontent
[FC140]
Function:
calculate_tankcontent
[FC140]
The actual program is
contained in this
example.
Is called by Main [OB1].
calculate_tankcontent
[FC140]
The actual program is
contained in this
example.
Is called by Main [OB1].