General Programming; Operating System And User Program; Program Blocks - Siemens S7-1200 Programming Manualline

3 General Programming

3.1 Operating system and user program

3 General Programming
3.1 Operating system and user program
SIMATIC controllers consist of operating system and user program.
The operating system organizes all functions and sequences of the controller
that are not connected with a specific control task (e.g. handling of restart,
updating of process image, calling the user program, error handling, memory
management, etc.). The operating system is an integral part of the controller.
The user program includes all blocks that are required for the processing of
your specific automation task. The user program is programmed with program
blocks and loaded onto the controller.
Figure 3-1: Operating system and user program
Hardware
For SIMATIC controllers the user program is always executed cyclically. The
"Main" cycle OB already exists in the "Program blocks" folder after a controller was
created in STEP 7. The block is processed by the controller and recalled in an
infinite loop.
3.2

Program blocks

In STEP 7 (TIA Portal) there are all familiar block types from the previous STEP 7
versions:
Organization blocks
Function blocks
Functions
Data blocks
Experienced STEP 7 users will know their way around straight away and new
users can very easily get familiar with the programming.
Advantages
You can give your program a good and clear structure with the different block
types.
Due to a good and structured program you get many function units that can be
multiply reused within a project and also in other projects. These function units
then usually only differ by a different configuration (see chapter
3.2.8 Reusability of blocks).
Programming Guideline for S7-1200/1500
V1.2, Entry ID: 81318674
User
program
OB
Operating
Main
system
cyclic
call
FB FC
Local
FC
FC
Global
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