Siemens SIMATIC S7-400H System Manual page 324

Stand-alone operation
Changing from stand-alone mode to redundant mode, rack number 0
1. Insert the synchronization modules into the CPU.
2. Run an unbuffered power cycle, for example by removing and inserting the CPU, or
Changing from stand-alone mode to redundant mode, rack number 1
1. Set rack number 1 on the CPU.
2. Install the CPU.
3. Insert the synchronization modules into the CPU.
System modification during operation in stand-alone mode
With a system modification during operation, it is also possible to make certain configuration
changes in RUN on fault-tolerant CPUs. The procedure corresponds to that for standard
CPUs. Processing is halted during this, but for no more than 2.5 seconds (configurable),
During this time, the process outputs retain their current values. In process control systems
in particular, this has virtually no effect on the process. See also the
during Operation via CiR"
System modifications during operation are only supported with distributed I/O. They require a
configuration as shown in the figure below. To avoid overcomplicating the matter, this shows
only one DP master system and one PA master system.
Figure B-1
324
download a project to the CPU in which it is configured for redundant mode.
Overview: System structure for system modifications during operation
manual.
"Modifying the System
System Manual, 09/2007, A5E00267695-03
S7-400H