Installing the S7-400
2-8 AutomationSystem S7-400 Hardwareand Installation
A5E00850741-01
2.3 Segmented CR

Properties

The “segmented” characteristic relates to the configuration of the CR. In the
(non-segmented) CR the I/O bus is continuous and interconnects all 18 or 9 slots;
in the segmented CR, however,the I/O bus consists of two I/O bus segments.
A segmented CR has the following important characteristics:
•The communication bus is continuous (global), whilst the I/O bus is divided into
two I/O bus segments of 10 and 8 slots respectively.
•One CPU can be inserted per local bus segment.
•The two CPUs in a segmented CR may be in different operating states.
•The two CPUs can communicate with each other via the communication bus.
•All the modules inserted in a segmented CR are powered by the power supply
module at slot 1.
•Both segments have a common backup battery.
The following figure shows a segmented CR with divided I/O bus and continuous
communication bus.
I/O bus
Segment 1 I/O bus
Segment 2
SEG1 SEG1 SEG1 SEG1 SEG1 SEG1 SEG1 SEG1 SEG1 SEG1 SEG2 SEG2 SEG2 SEG2 SEG2 SEG2 SEG2 SEG2
1 2 3 4 5 67 8 9101112131415161718
1
SEG1 11
SEG2
Communication bus