Failure And Replacement Of A Cpu - Siemens SIMATIC S7-400H System Manual

Failure and replacement of components during operation
16.2 Failure and replacement of components during operation
16.2.1

Failure and replacement of a CPU

Complete replacement of the CPU is not always necessary. If only the load memory fails, it
is enough to replace the corresponding memory card. Both cases are described below.
Starting situation for replacement of the CPU
Failure
The S7-400H is in redundant system mode and a
CPU fails.
Requirements for replacement
The module replacement described below is possible only if the "new" CPU
● has the same operating system version as the failed CPU and
● if it is equipped with the same load memory as the failed CPU.
Procedure
Follow the steps below to replace a CPU:
Step
1
2
3
4
5
266
NOTICE
New CPUs are always shipped with the latest operating system version. If this differs
from the version of the operating system of the remaining CPU, you will have to equip
the new CPU with the same version of the operating system. Either create an operating
system update card for the new CPU and use this to load the operating system on the
CPU or load the required operating system in HW Config with "PLC -> Update
Firmware", see section Updating the firmware without a memory card (Page 83).
What has to be done?
Turn off the power supply module.
Replace the CPU. Make sure the rack
number is set correctly on the CPU.
Insert the synchronization modules.
Plug in the fiber-optic cable connections of
the synchronization modules.
Switch the power supply module on again.
How does the system react?
The partner CPU switches to single mode.

The partner CPU reports the event in the

diagnostic buffer and in OB 72.
How does the system react?
The entire subsystem is switched off

(system operates in single mode).
–
–
–
CPU runs the self-tests and changes to

STOP.
System Manual, 03/2012, A5E00267695-11
S7-400H