Siemens Simatic S7-300 CPU 31xC Series User Manual

Configuring
4.5 Arrangement of modules on a single rack
S7-300, CPU 31xC and CPU 31x: Installation
Operating Instructions, Edition 08/2004, A5E00105492-05
4-7
4.5 Arrangement of modules on a single rack
Reasons for using one or multiple racks
The number of racks you need will depend on your application.
Reasons for using a single rack: Reasons for distributing modules between
several racks
• Compact, space-saving use of all your
modules
• Local use of all modules
• Fewer signals to be processed
• More signals to be processed
• Insufficient number of slots
Note
If you opt for the installation on a single rack, insert a dummy module to the right of the CPU
(order no.: 6ES7 370-0AA01-0AA0). This gives you the option of adding a second rack for
your application, simply by replacing the dummy module with an interface module, and
without having to reinstall and rewire the first rack.
Rules: Layout of modules on a single module rack
The following rules apply to module installations on a single rack:
• No more than eight modules (SM, FM, CP) may be installed to the right of the CPU.
• The accumulated power consumption of modules mounted on a rack may not exceed
1.2 A on the S7-300 backplane bus.
Reference
For further information, refer to the technical data, for example, in the S7-300 Module
Specifications Reference Manual
or in the Reference Manual for your CPU .
Example
The figure below shows a layout with eight signal modules in an S7-300 assembly.
CPU
PS
SM1
SM2
SM3
SM4
SM5
SM6
SM7
SM8

Siemens Simatic S7-300 CPU 31xC Series Specifications

General

Series	S7-300 CPU 31xC
Power Supply	24 V DC
Communication Interfaces	MPI, PROFIBUS DP
Programming Languages	LAD, STL, FBD, SCL
Operating Temperature	0°C to +60°C
Memory	48 KB - 512 KB
Dimensions	40 x 125 x 130 mm (varies by model)