Arranging Modules On A Single Module Rack - Siemens SIMATIC S7-300 Hardware And Installation Manual

4.4

Arranging modules on a single module rack

One or multiple module racks?
The answer to this query is based on the nature of your application. Reasons for
using a single module rack could be:
• Compact, space-saving module application
• Central module application
• Low volume of signals to be processed
Possible reasons for a distribution to multiple module racks:
• High volume of signals to be processed
• No more slots available
Tip: If you choose installation on a single module rack, insert a dummy module to
the right side of the CPU (Order No.: 6ES7 370-0AA01-0AA0). This gives you the
option of inserting a second module rack for your application in the future, simply
by replacing the dummy module with an interface module and without having to
reinstall and rewire the first module rack.
Rules: Arranging modules on a single module rack
The following rules apply to single-rack module installations:
• No more than eight modules (SM, FM, CP) may be installed to the right side of
the CPU.
• The total current load on the S7 backplane bus of all modules mounted on a
single module rack must not exceed
1.2 A (except with CPU 312C or CPU 312 IFM)
–
0.8 A with CPU 312C or CPU 312 IFM
–
The power consumption of modules ...
can be found in their technical data, e.g. S7-300 Module Data Reference Manual.
S7-300 Programmable Controller Hardware and Installation
A5E00105492-01
Configuring
4-7