Switch To Cpu With Modified Configuration; Load Memory; Working Memory - Siemens SIMATIC S7-400H Manual

Linking and Synchronizing
6.2.3

Switch to CPU with modified configuration

If link-up and update was triggered from STEP 7 using the option "Switch to CPU
with modified configuration" the behavior will be different as regards processing of
the memory content.

Load memory

The content of the load memory is not copied from the master CPU to the standby
CPU.

Working memory

The following components are transferred from the main memory of the master
CPU to the standby CPU:
• Contents of all the data blocks having the same interface time stamp in the two
load memories and with the attributes "Read Only" and "unlinked" not set.
• Data blocks generated in the master CPU by SFC.
The DBs generated in the standby CPU by SFC are reset.
If a data block with the same number is also contained in the load memory of
the standby CPU link-up will be interrupted with an entry in the diagnostics
buffer.
• Process images, timers, counters and memory markers
• Diagnostics buffer
If the diagnostics buffer in the standby CPU is configured smaller than in the
master CPU only the number of entries for which the standby CPU is
configured will be transferred. The most current entries will be selected from the
master CPU.
If there is insufficient memory the link-up will be interrupted with an entry in the
diagnostics buffer.
If data blocks that contain instances of SFBs of the S7 communication information
have been modified then these instances will be returned to the state they were in
before first being called.
Note
When switching to a CPU with a modified configuration the load memories of the
master and standby may be of different sizes.
6-12
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07