Siemens SIMATIC PCS 7 Function Manual page 80

Fault-tolerant Solutions in PCS 7
3.5 Solutions for OS servers
Redundancy connection
You need the following components to make the redundancy connection, depending on the
distance to be bridged:
Maximum distance
10 m
100 m
1000 m
Availability
The availability of the complete system is ensured even if one of the two OS servers fails
because the two OS servers form an independent redundancy node.
Note
The buses marked with * (terminal bus and plant bus) can be configured redundantly with
optical or electronic switch modules.
Delaying the transfer of archives
If a redundant partner is not available or is deactivated, the transfer of the archives of the
redundant partner will be delayed. The transfer of archives is started or continued only when
the partner becomes available again and synchronization of the archives is completed.
Since the storage capacity of the ring buffer for Tag Logging and Alarm Logging is limited,
there is a risk of data loss if the redundant partner is out of action for a longer period of time.
Additional information
● Section "Network components (Page 41)"
● Section "How to configure an OS server and its redundant OS partner server (Page 127)"
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Required components
Null modem cable
● Crossover network cable
● Per server: A free network connection (see
section "Network components (Page 41)")
Fiber-optic cable
Per server:
● A free network connection
(see section "Network components
(Page 41)")
● 1 Ethernet cable
● 1 media converter
(e.g., SCALANCE X101-1)
Connection
Serial connection
Ethernet connection
Ethernet connection
Fault-tolerant Process Control Systems (V8.0)
Function Manual, 03/2012, A5E02779471-02