Split Rack - Siemens SIMATIC S7-400 Configuration And Use Manual

Two CPUs in a Split Rack
With split racks, the I/O bus and communication bus are divided into two
segments. A CPU can be installed in each segment.
Functionally, a split rack represents two electrically isolated racks on the same
mounting rail.
Figure 6-5 shows a configuration of a split rack with 2x9 slots.
Figure 6-5
Advantages
Split racks are usually used for compact redundant S7-400H systems (two devices
or systems in a single rack).
Automation System S7-400 Configuration and Use
A5E00442711-02
Device I
1 2 3 4 5 6 7

Split rack

Configuration Variants of the S7-400
Device II
8 9 1 2 3 4 5 6 7 8 9
6-9