Siemens SIMATIC S7-400H Manual page 268

Modifying the System During Operation
Procedure
Perform the steps below in the order specified:
Step What Has To Be Done?
1 Switch the standby CPU to STOP mode using
the PG.
2 If you want to expand the main memory:
A Turn off the power supply for the standby
CPU.
B Unplug the standby CPU from the central
controller (CC).
C Install the desired memory modules as
described in the installation manual
S7-400, M7-400 Programmable Control-
lers, Hardware and Installation.
D Plug the CPU back into in the CC.
E Make sure that the synchronization link is
re-established and that the mode selector
of the standby CPU is switched to RUN or
RUN-P.
F Turn the power supply for the standby
CPU back on.
3 If you want to expand the load memory:
Unplug the existing memory card from the
CPU and plug in a memory card of the same
type with the desired (larger) capacity.
4 Reset the standby CPU using the PG.
5 Start the standby CPU by means of the menu
command PLC > Mode > Switch to CPU
with... expanded memory configuration.
6 Turn off the power supply for the second
CPU.
7 Modify the memory components of the
second CPU as you did for the first CPU in
steps 2 to 4.
8 Start the second CPU using the programming
device.
11-48
How Does the System React?
The system is working in single mode.
Subsystem is disabled for periods.
Standby CPU requests reset.
–
•
Standby CPU links up, is updated and
becomes the master.
•
Previous master CPU goes into STOP.
•
System works in single mode.
Subsystem is disabled.
–
•
Second CPU links up and is updated.
•
System works redundant system mode
again.
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07