Siemens SIMATIC S7-400 Hardware And Installation Manual page 120

Networking
Example: Terminating Resistor in the MPI Network
The figure below shows where you have to connect the terminating resistor in a
possible configuration for an MPI network.
S7-400
S7-400
OP
Terminating resistor switched on
5-10
www.gkbpx.com
Programming device
S7-400
Spur line
Programming device
S7-400 and M7-400 Programmable Controllers, Installation Manual
OP
S7-300
RS 485
repeater
C79000-G7076-C424-01