Siemens S7-300 - Example: Maximum Distance in the MPI Subnet

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S7-300 Automation System, Hardware and Installation: CPU 312IFM - 318-2 DP
A5E00203919-01
5-45
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The figure below shows you:
• a possible MPI Subnet configuration
• maximum distances possible in an MPI subnet
• the principle of “Line extension“ using RS485 repeaters
max. 50 m
max. 50 m
PG
PG
RS 485-
Repeater
max. 1000 m
3
S7-300
CPU
PS
CPU
MPI addr. 3
3
S7-300
CPU
PS
CPU
MPI addr. 5
3
S7-300
CPU
PS
CPU
MPI addr. 6
MPI addr. 4
OP 27
MPI addr. 7
3
S7-300
CPU
PS
CPU
MPI addr. 8
RS 485-
Repeater
MPI addr. 9
OP 27
3
S7-300
CPU
PS
CPU
MPI addr. 10
MPI addr. 11
OP 27
MPI addr.
1
1
1
1
1
1
2
Figure 5-15 Example: Maximum distance in the MPI subnet
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 Terminating resistor inserted
 PG connected by means of a stub cable for maintenance purposes