Siemens S7-300 - Example of an MPI Subnet

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S7-300 Automation System, Hardware and Installation: CPU 312IFM - 318-2 DP
5-44 A5E00203919-01
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The figure below shows you the block diagram of an MPI subnet.
PG
PG
OP 27
S7-300
1
1
3
5
SF
SF
BUSF
BUSF
DC5V
DC5V
FRCE
FRCE
RUN
RUN
STOP
STOP
CPU
PS
MPI addr. 2
S7-300
CPU
PS
CPU
3
S7-300
CPU
PS
CPU
3
S7-300
CPU
PS
CPU
CP
2
2
3
S7-300
CPU
PS
CPU
3
S7-300
CPU
PS
CPU
OP 27
3
S7-300
CPU
PS
CPU
FM
MPI addr. 1
MPI addr. 3 MPI addr. 4
MPI addr. 5 MPI addr. 6
MPI addr. 7
PROFIBUS
4
MPI addr. 9MPI addr. 8MPI addr. 10MPI addr. 11MPI addr. 12
OP 27
MPI addr. 13
MPI addr. 0
3
3
Figure 5-14 Example of an MPI subnet
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 Terminating resistor inserted
 S7-300 and OP 27 have subsequently been connected to the MPI subnet using their MPI default
address.
 With CPU 318-2 DP, a separate MPI address is not assigned to CPs or FMs. With S7-300 CPUs (without
CPU 318-2 DP). you can also freely assign MPI addresses for the CPs/ FMs.
 In addition to the MPI address, the CP also has a PROFIBUS address (7 in this case).
 Connected via a stub cable using the default MPI address for commissioning/maintenance only