Downloading Without Reinitialization - Siemens S7-1200 Programming Manualline

3 General Programming
3.2 Program blocks
Figure 3-12: Global DB as central data memory
OB
Advantages
Well structured memory area
High access speed
Properties
All blocks in the user program can access global DBs.
The structure of the global DBs can be arbitrarily made up of all data types.
Global DBs are either created via the program editor or according to a
previously created "user-defined PLC data type" (see chapter 3.6.3 STRUCT
data type and PLC data types).
Recommendation
Use the global DBs when data is used in different program parts or blocks.
Note You will find further information in the following entry:
What access types, value columns and operating options are there for the global
data blocks in STEP 7 V12?
http://support.automation.siemens.com/WW/view/en/68015631
3.2.7

Downloading without reinitialization

In order to change user programs that already run in a controller, S7-1200
(firmware V4.0) and S7-1500 controllers offer the option to expand the interfaces of
optimized function or data blocks during operation. You can load the changed
blocks without setting the controller to STOP and without influencing the actual
values of already loaded tags.
Programming Guideline for S7-1200/1500
V1.2, Entry ID: 81318674
FC
DB
FB
Local
36