Slot rules Siemens 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.