Siemens SIMATIC ET 200M Operating Instructions Manual page 48

Assignment planning
3.5 Configuring the mechanical structure
Installation Options
Dependent on the length of the rails you can fit up to 9 active bus modules:
Figure 3-9
Placement of the PS 307 power supply modules
Redundancy with 2 x IM
153-2
IM 153-1 /-2 for "Module
change in operation"
See also
Order Numbers for the ET 200M (Page 247)
46
Configuration with active bus modules
If you use the 530 mm rail, place the BM IM/IM in the right-hand of the
two latched positions on the rail Then you can install either 2 x PS
307; 2A or 1 x PS 307; 5A to the rail to the left of the BM IM/IM.
Otherwise you must fit the power supply modules to a separate S7
standard rail.
Recommendation: Each IM 153-2 has its own PS.
Alongside the IM 153-x, the PS 307; 2A is also compatible with the
BM PS/IM.
The PS 307; 5A or 10A are not compatible with the BM PS/IM. You
must fit these to a separate S7 standard rail.
Operating Instructions, 12/2008, EWA-4NEB780600602-08
ET 200M