Switch To Cpu With Modified Configuration - Siemens SIMATIC CPU 410 System Manual

18.13.3

Switch to CPU with modified configuration

Switch to CPU with modified configuration
You may have modified the hardware configuration on the standby CPU. The necessary
steps are described in Section Replacement of failed components during redundant
operation (Page 223).
Note
Even though you have not modified the hardware configuration on the standby CPU, there is
nevertheless a master/standby changeover and the former master CPU switches to STOP.
When you initiate the link-up and update operation from STEP 7 with the "Switch to CPU
with modified configuration" option, the system reacts as follows with respect to handling of
the memory contents.
Load memory
The contents of the load memory are not copied from the master to the standby CPU.
Work memory
The following components are transferred from the work memory of the master CPU to the
standby CPU:
● Contents of all data blocks assigned the same interface time stamp in both load
memories and whose attributes "read only" and "unlinked" are not set.
● Data blocks generated in the master CPU by SFCs.
The DBs generated in the standby CPU by means of SFC are deleted.
If a data block with the same number is also contained in the load memory of the standby
CPU, the link-up operation is cancelled with an entry in the diagnostics buffer.
● Process images, timers, counters, and bit memories
The status of SFB instances of S7 communication contained in modified data blocks is
restored to the status prior to their initial call.
CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC
Supplementary information
18.13 Link-up and update sequence
351