I am building a redundant system using S7-1515R-2 CPU with TIA V16 version. Creating the hardware, there is not possible to insert any other card to the rack. Even power modules (PM) can not be inserted to the rack. How should I make the power feeding to the CPU. Should I use two power modules/devices or only one. How can I insert IO-cards to the system, is the only possibility to use Profinet IM-cards. In this system I am connecting the bus to the ring and using S2.