How do I link an S7-400 with S5 expansion units?
You can connect the following S5 expansion units to an S7-400:
EG 183U, EG 185U, EG186U, ER 701-2, ER 701-3
The interface is established via the IM463-2, which is plugged into the S7-400 CPU. Insert an IM 314 into the S5 expansion unit. Even expansion units which are connected decentrally via an IM 463-2 can be expanded centrally again.
You can find detailed information in the manual "S7-400 Module Data", chapter 7 (S5 interface in the IM 463-2)" in Entry ID 1117740.