Siemens SIMATIC S7-400 Installation Manual page 19

Connecting the CR and ER(s)
To connect one or more ERs to a CR, you must fit one or more send IMs in the CR.
The send IMs have two interfaces. You can connect one chain of up to four ERs to
each of the two interfaces of a send IM in the CR.
Different IMs are available for local connection and remote connection.
Connecting with a 5 V Supply
For a local connection with the IM 460-1 and IM 461-1, the 5 V supply voltage is
also transferred via the interface modules. There must therefore be no power
supply module inserted in an ER connected to an IM 460-1/IM 461-1.
Up to 5 A may flow through each of the two interfaces of an IM 460-1. This means
that each ER connected via an IM 460-1/461-1 can be powered with a maximum of
5 A at 5 V. For further details, see the Reference Manual, Chapter 6.
Overview of the Connections
Observe the connection rules at the end of this section.
Send IM
Receive IM
Max. number of connectable
EMs per chain
Max. distance
5 V transfer
Max. current transfer per inter-
face
Communication bus transmission
Automation System S7-400 Hardware and Installation
A5E00850741-01
Local Connection
460-0 460-1
461-0 461-1
4 1
5 m 1.5 m
No Yes
-- 5 A
Yes No
Installing the S7-400
Remote Connection
460-3 460-4
461-3 461-4
4 4
102.25 m 605 m
No No
-- --
Yes No
2-3