Siemens S7-400 installation manual Segmented CR, Properties

Installing the S7-400

2.3Segmented 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.

1										11
SEG1									SEG2
1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18
SEG1	SEG1	SEG1	SEG1	SEG1	SEG1	SEG1	SEG1	SEG1	SEG1	SEG2	SEG2	SEG2	SEG2	SEG2	SEG2	SEG2	SEG2

I/O bus Segment 1

I/O bus Segment 2

Communication bus

2-8	Automation System S7-400	Hardware and Installation
		A5E00850741-01