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S7-300 Automation System, Hardware and Installation: CPU 31xC and CPU 31x
5-32
A5E00105492-03
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03,352),%86'33W3
These subnets are the most frequently used for S7-300 CPUs, so they are
discussed in detail below.
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In the following, all networked devices are referred to as nodes.
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A segment is a bus link between two terminating resistors. A segment can include
up to 32 nodes. It is also limited by the permitted line length, depending on the
transmission rate.
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These maximum transmission rates are possible:
•
MPI
–
CPU 317-2 DP: 12 Mbps
–
All other CPUs: 187.5 Kbps
•
PROFIBUS DP: 12 Mbps
•
PtP:
–
Half duplex: 38.4 Kbps
–
Full duplex: 19.2 Kbps
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Maximum possible number of nodes per subnet:
Table 5-13
Nodes on the subnet
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03,
352),%86'3
3W3
Number
127
126
1)
2
Addresses
0 to 126
0 to 125
-
Remarks Default:
32
addresses
Reserved are:
•
address 0 for PG
•
address 1 for OP
of those:
1 Master (reserved)
1 PG connection (address 0
reserved)
124 slaves or other masters
-
1)
Note the CPU-specific maximum specifications in the CPU manual.