Siemens Simatic S7-1500 - Loss of Redundancy CPU

Commissioning
12.4 Operating and system states
S7-1500R/H redundant system
System Manual, 01/2024, A5E41814787-AF
411
⑪STARTUP → STOP
Transition
Description
Effects
System state
transition
STARTUP → STOP
The redundant system switches from the STARTUP system state to the STOP
system state if:
• The primary CPU detects an error during startup that prevents further
processing
or
• You set the primary CPU to STOP with the PG/PC, the display or the mode
selector
or
• The primary CPU processes a STOP command in startup OB
or
• In the CPU properties, you have set the following for startup behavior:
– Too short a configuration time for the distributed I/O and
– "Startup CPU only if compatible"
The primary CPU switches to STOP.
This system state tran-
sition does not have
any effect on data.
Primary CPU op-
erating state
transition
This operating state
transition does not
have any effect on
data.
12.4.8 Loss of redundancy CPU
Introduction
In the case of failure or STOP operating state of a CPU in S7-1500R/H the redundant system
changes from RUN-Redundant system state to RUN-Solo system state. The operating system
calls the OB 72 "CPU redundancy error". The OB 82 is also called for the central modules (e.g.
CPs) of the failed CPU.
The redundancy loss due to failure/switching to STOP of the CPU is considered (CPU
redundancy error) in the following section. The system and operating state transitions ⑦
from the section System and operating state transitions (Page 400) are explained in more
detail:
• RUN-Redundant → RUN-Solo
• RUN-Redundant → RUN
Note
Loss of redundancy of I/O
If a loss of redundancy occurs in S7
-1500H in the system state RUN-Redundant at a
redundant R1/S2 device, then one AR of two ARs of a R1/S2
device has failed. The operating
system calls the OB 70 "I/O redundancy error". You can find more information in the
Programming the S7-1500R/H (Page 317) section.