Supplementary information
16.12 Link-up and update sequence
CPU 410-5H Process Automation/CPU 410 SMART
266 System Manual, 10/2013, A5E32631667-AA
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
If there is insufficient memory, link-up is cancelled with an entry in the diagnostics buffer.
The status of SFB instances of S7 communication contained in modified data blocks is
restored to the status prior to their initial call.
Note
When changing over to a CPU with modified configuration, the size of load memories in the
master and reserve may be different.
During the link-up, the user program blocks (OBs, FCs, FBs, DBs, SDBs) of the master are
transferred from the load memory and work memory to the reserve.
Disabling of link-up and update
Link-up and update entails a cycle time extension. This includes a period during which no I/O
updates are performed; see Chapter Time monitoring (Page 110). You must pay special
attention to this if you are using distributed I/O and a master/standby changeover occurs
after the update (thus, when the configuration is modified during operation).
Always perform link-up and update operations when the process is not in a critical state.
To Next Page
Loading...
Need help?
General
