Siemens SIMATIC PCS 7 CPU 410-5H System Manual page 139

Additional aspects
● Both fault-tolerant CPUs of a fault-tolerant system can have different protection levels in
STOP.
● The protection level is transferred from the master to the standby during link-up/update
operations.
● The set protection levels of both fault-tolerant CPUs are retained if you make
modifications to the plant during operation.
● The protection level is transferred to the target CPU in the following cases:
– Switch to CPU with modified configuration
– Switching to a CPU with modified PO limit
– Switching to a CPU with modified operating system
– Switching to a CPU using only one intact redundant link
CPU 410-5H Process Automation
System Manual, 09/2014, A5E31622160-AB
Special functions of the CPU 410-5H
9.1 Security levels
139