Technical data

Memory areas and retentive memory
2.4 Memory behavior when loading software changes
Structure and Use of the CPU Memory
18 Function Manual, 01/2013, A5E03461664-01
2.4 Memory behavior when loading software changes
Introduction
In the STOP and RUN modes of the S7-1500 CPU, you can load changes to the software
without this affecting the actual values of tags already loaded.
In STEP 7, you load changes to the software under "Download to device > Software (only
changes)".
Impact of software changes on PLC tags
You can load the following software changes without affecting the actual values of tags that
have already been loaded:
● Name change
● Comment change
● Addition of new tags
● Deletion of tags
● Change of retentivity settings for Bit memories, times, and counters (Page 13)
The act
ual va
lues are affected by loading the following software changes:
● Data type change
● Address change
Impacts of software changes on data blocks with memory reserve
If you are using memory reserve for data blocks ("Optimized block access" attribute and
"Download without reinitialization" button activated), you can load the following software
changes without this reinitializing the actual values of tags which have already been loaded:
● Start value change
● Comment change
● Addition of new tags
To load the following software changes, you must deactivate the "Download without
reinitialization" button. During the next load, all actual values of the data block will be
reinitialized:
● Name change
● Data type change
● Retentivity change
● Deletion of tags
● Changes to the memory reserve settings