Struct Data Type And Plc Data Types - Siemens S7-1200 Programming Manualline

3 General Programming
3.6 Symbolic addressing
3.6.3

STRUCT data type and PLC data types

The STRUCT data type represents a data structure which is made up of elements
of different data types. The declaration of a structure is performed in the respective
block.
Figure 3-27: Structure with elements with different data types
In comparison to structures, PLC data types are defined across the controller in the
TIA Portal and can be centrally changed. All usage locations are automatically
updated.
PLC data types are declared in the "PLC data types" folder in the project navigation
before being used.
Figure 3-28: PLC data types
Advantages
A change in a PLC data type is automatically updated in all usage locations in
the user program.
Recommendation
Use the PLC data types to summarize several associated data, such as, e.g.
frames or motor data (setpoint, speed, rotational direction, temperature, etc.)
Always use PLC data types instead of structures for the multiple uses in the
user program.
Use the PLC data types for structuring into data blocks.
Use the PLC data types in order to specify a structure for a data block. The
PLC data type can be used for any number of DBs. You can easily and
conveniently create as many DBs of the same structure and adjust them
centrally on the PLC data type.
Programming Guideline for S7-1200/1500
V1.2, Entry ID: 81318674
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