Rules For Arranging Fault-Tolerant Station Components; Configuring Hardware - Siemens SIMATIC S7-400H System Manual

Configuring with STEP 7
15.1 Configuring with STEP 7
15.1.1

Rules for arranging fault-tolerant station components

The following rules have to be complied with for a fault-tolerant station, in addition to the
rules that generally apply to the arrangement of modules in the S7-400:
● Insert the CPUs into the same slots.
● Redundantly used external DP master interfaces or communication modules must be
● Insert an external DP master interface for redundant DP master systems only into the
● Redundantly used modules (for example, CPU 417-5H, DP slave interface module IM
Layout rules
● A fault-tolerant station may contain up to 20 expansion devices.
● Assign module racks with even numbers only to central rack 0, and racks with odd
● Modules with communication bus interface can be operated only in racks 0 through 6.
● Communication-bus capable modules are not permissible in switched I/O.
● Pay attention to the rack numbers for operation of CPs for fault-tolerant communication in
● A rack number is also assigned for DP master no. 9 onwards if the central rack contains
Compliance with the rules is monitored automatically by STEP 7 and considered accordingly
during configuration.
15.1.2

Configuring hardware

The simplest way of achieving a redundant hardware configuration consists in initially
equipping one rack with all the redundant components, assigning parameters to them and
then copying them.
You can then specify the various addresses (for one-sided I/O only!) and arrange other, non-
redundant modules in individual racks.
Special features in presenting the hardware configuration
In order to enable quick recognition of a redundant DP master system, it is represented by
two parallel DP cables.
260
inserted in the same slots in each case.
CPUs and not into the expansion devices.
153-2) must be identical, i.e. they must have the same order number, the same product
version, and the same firmware version.
numbers only to central rack 1.
expansion devices:
The numbers must be directly sequential and begin with the even number, e.g. rack
numbers 2 and 3, but not rack numbers 3 and 4.
DP master modules. The number of possible expansion racks is reduced as a result.
System Manual, 03/2012, A5E00267695-11
S7-400H