Add a DP slave in sytem ( support Redundance)

Hi everyone!

I have 2 PLC 412-3H run paralle (1 Master, 1 Slave). 2 PLC connect profibus network with I/O module S7300 throught 2 IM153-2 module. I have a Getway GW-7552 (DP slave) to change profibus to modbus.How to way i can give GW-7552 in profibus network to system. If i use Y-link (add Y-coupler module), my I/O module is using how to do. Can you support me about this problem.

Thank you!