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Siemens SIMATIC NET PROFIBUS User Manual

Page 73

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Configuring Networks

3-7

PROFIBUS Networks SIMATIC NET
6GK1970-5CA20-0AA1 Release 2 05/2000

Table 3-5

Examples Illustrating the Configuration Rules

No special conditions if the length of the LAN cable
between two DTEs > 10 m

LAN cable > 10 m

> 10 m

S7-400

S7-300

No special conditions if the length of the LAN ca-
bles between two DTEs is greater than the sum of
values of both DTEs.

If a bus terminal or a bus connector has a PG inter-
face, a connected PG connecting cable must be
taken into account when calculating the values.

Bus cable, e.g. 5 m

V = 1.5 + 1.0 + 0.1 = 2.6

5 m > 2.6 m (sum of the values in

meters)

5 m

V = 1.0

V = 1.5

V = 0.1

S7-400

S7-300

Take the values of a group into account if the sum
of the values is greater than the LAN cable bet-
ween the DTEs.

Elements can be close to each other providing the
total value of a group does not exceed 5.

LAN cable e.g. 0.5 m group

V = 1.5 + 1.5

0.5 m < 3 m

group formed

sum of the values

5

0.5 m

V = 1.5

V = 1.5

S7-400

S7-400