The IM153-1 is one reasonably priced variant that is excellently suited for most applications in the manufacturing environment. It permits the use of up to 8 S7-300 I/O modules. • The IM 153-1 interface module serves as the head module (IM; Interface Module) of the ET 200M. Up to 8 or 12 I/O modules from the module product range of the S7-300 automation system can be connected to the interface module. • The interface module and the necessary I/O modules are assembled on a profile rail for the S7-300. During assembly, the I/O modules are connected to one another using bus connectors and using the IM 153 interface modules. • For redundant operation, two IM 153-2 are mounted onto the BM IM/IM bus module. Special profile rails are available to accommodate the bus modules. • When equipping the IM153 with S7-300 modules, slot rules do not have to be taken into account.