Rules for Arranging Modules on cntraral rack

Rules for Arranging Modules (SIMATIC 300) 
Basic Rule
Modules must be inserted in the rack without gaps.
Exception: For installations with one rack, one slot in the configuration table must remain free
(reserved for the interface module). With the S7-300, this is slot 3 and with M7-300, the slot after the
module group (slot 3, 4, 5, or 6). In the actual configuration there is no gap because the backplane bus
would be interrupted.
 
Slot Rules (S7-300)
Rack 0:
•  Slot 1: Power supply only (for example, 6ES7 307-...) or empty
•  Slot 2: CPU only (for example, 6ES7 314-...)
•  Slot 3: Interface module (for example, 6ES7 360-.../361-...) or empty
•  Slots 4 through 11: Signal or function modules, communications processors, or free.
Racks 1 to 3:
•  Slot 1: Power supply module only (for example, 6ES7 307-...) or empty
•  Slot 2: Free
•  Slot 3: Interface module
•  Slots 4 through 11: Signal or function modules, communications processors (dependent on the
inserted interface module), or free.
!--RELATED-POSTS-STARTS-->