Siemens S7-1200 Programming Manualline page 50

3 General Programming
3.6 Symbolic addressing
Figure 3-26: Indirect field access
Advantages
Simple access since the data type of the ARRAY elements is irrelevant for the
access.
No complicated pointer creation required
Fast creation and expansion possible
Useable in all programming languages
Properties
Structured data type
Data structure made of fixed number of elements of the same data type
ARRAYs can be created also multi-dimensional
Possible indirect access with runtime tag with dynamic index calculation at
runtime
Recommendation
Use ARRAY for indexed accesses instead of pointer (e.g. ANY pointer). This
makes it easier to read the program since an ARRAY is more meaningful with
a symbolic name than a pointer in a memory area.
As run tag use the INT data type as temporary tag for highest performance.
Use the "MOVE_BLK" instruction to copy parts of an ARRAY into another one.
Use the "GET_ERR_ID" instruction to catch access errors within the Array.
Note You will find further information in the following entry:
How do you implement an array access with an S7-1500 with variable index?
http://support.automation.siemens.com/WW/view/en/67598676
Programming Guideline for S7-1200/1500
V1.2, Entry ID: 81318674
LAD / FBD:
SCL:
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