Possible Hardware Modifications; How Is A Hardware Change Made?; Which Components Can Be Modified? - Siemens SIMATIC S7-400H Manual

Modifying the System During Operation
11.1

Possible Hardware Modifications

How is a hardware change made?

If the hardware components concerned are suitable for unplugging or plugging in
live the hardware modification can be carried out in redundant system mode.
However, since loading a modified hardware configuration in redundant system
mode would result in the fault-tolerant system stopping this must temporarily be
put into single mode. In single mode the process is then controlled by only one
CPU while the desired configuration modifications are carried out on the other
CPU.
Notice
You should load configuration changes into the CPU only from "Configure
Hardware".
Since in this process the load memory content of both CPUs has to be modified
more than once, expansion of the integrated load memory with a RAM card is to
be recommended (at least temporarily) is recommended.
You may only perform the substitution of the FLASH card with required for this with
a RAM card if the FLASH card has as much storage space at most as the largest
RAM card available. If your FLASH card is larger than the largest available RAM
card, you must perform the necessary configuration and program changes in such
small steps that there is space for them in the integrated load memory.
Caution
!
Whenever you make hardware changes, ensure that the synchronization link
between the two CPUs is re-established before the standby CPU is started or
activated. When the power supplies of the CPUs are switched on, the IFM1F and
IFM2F LEDs – which are used to indicate faults on the interfaces for memory
submodules – must go out on both CPUs..

Which components can be modified?

The following modifications can be made to the hardware configuration during
operation:
• Adding or removing modules to/from the central or expansion units (e.g.
one-way I/O module).
11-2
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07