Assigning Parameters To Modules In A Fault-Tolerant Station - Siemens SIMATIC S7-400H System Manual

12.2.3

Assigning parameters to modules in a fault-tolerant station

Introduction
Assigning parameters to modules in a fault-tolerant station is no different from assigning
parameters to modules in S7-400 standard stations.
Procedure
All the parameters of the redundant components (with the exception of MPI and
communication addresses) must be identical.
The special case of CPUs
You can only edit the CPU0 parameters (CPU on rack 0). Any values that you specify for it
are automatically allocated to CPU1 (CPU on rack 1). The settings of CPU1 can not be
changed, with the exception of the following parameters:
● MPI address of the CPU
● CPU name, plant designation, location ID
Configuring modules addressed in the I/O address space
Always configure a module that is addressed in the I/O address space so that it is located
either entirely in the process image or entirely outside.
Otherwise, consistency can not be guaranteed, and the data may be corrupted.
I/O access using word or dword statements
The system loads the values to accumulator "0" if the word or dword for I/O access contains
only the first or the first three bytes, but not the remaining bytes of the address space.
Example: The I/O is at address 8 and 9 in the S7-400H CPU; addresses 10 and 11 are not
used. Access L ID 8 causes the system to load the value DW#16#00000000 into the
accumulator.
S7-400H
System Manual, 09/2007, A5E00267695-03
Configuring with STEP 7
12.2 Configuring with STEP 7
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