Synchronization modules
Synchronization modules are used to link the two central processing units. They are installed 
in the central processing units and interconnected with fiber-optic cable. Two synchronization 
modules are installed in each CPU.
Set the rack number for the H CPU as of firmware version V4.X directly on the CPU. The 
synchronization modules can be replaced in runtime.
The same rack number must be set at all synchronization modules up to firmware V3.x.
Fiber-optic cables for synchronization
The fiber-optic cables are connected to the synchronization modules and form the physical 
connection (redundancy link) between the two automation stations. The synchronization 
cables must not be cross-connected.
In addition to the standard lengths of 1 m, 2 m, and 10 m, custom-made synchronization cables 
are available in lengths up to 10 km.
Transmission medium
The suitable physical transmission medium depends on the range, resistance to interference 
and the transmission rate.
● Industrial Ethernet using fiber-optic cables or triaxial or twisted-pair copper lines can be 
used for communication between the automation system and the OS servers.
● PROFIBUS DP or PROFINET IO with electrical or optical components is used for 
communication from the automation system to the distributed I/O device.
The transmission media and communications processors can be configured redundantly. If 
the active communication component (CP, bus) fails, the communication automatically 
continues through the redundant connection.
High availability communication for plant bus:
● The communication modules should be configured to use ISO protocol.
● Exception: 
High availability communication with CPU 41x PN/DP and SOFTNET-IE S7 REDCONNECT
The communication modules need to be configured to use ISO-on-TCP.
Equipping the rack           
The hardware setup in the automation system and the configuration in HW Config must match:
● Rack (4, 9 or 18 slots for redundant and, in some cases, remote configuration)
● Power supply modules (in some cases redundant configuration)
● H CPU with sync modules in slots "IF1" and "IF2"
● If necessary: Communications processors (CP 443-1, CP 443-5 Extended)
High availability solutions in PCS 7
4.2 Solutions for automation systems
High Availability Process Control Systems (V9.0)
52 Function Manual, 05/2017, A5E39221836-AA