Technical data

Network configuration
3.1 Configuring electrical networks
PROFIBUS Network Manual
System Manual, Edition 04/2009, C79000-G8976-C124-03
45
Table 3- 5 Examples illustrating the configuration rules
No special conditions if the length of the bus cable between two end devices
> 10 m
> 10 m
S7-300S7-400
No special conditions if the length of the bus cables between two end
devices is greater than the sum of the weighting values of both end devices.
If a bus terminal or a bus connector has a PG interface, a connected PG
cable must be taken into account when calculating the weighting values.
Bus cable, for example 5 m
WV = 1.5 + 1.0 + 0.1 = 2.6
5 m > 2.5 m (sum of the weighting values in
meters)
S7-300
S7-400 PG
W = 0,1
W = 1,5
5 m
W = 1,0
Take the weighting values of a group into account if the sum of the weighting
values is greater than the bus cable between the end devices.
Elements can then be as close to each other as necessary.
The total weighting value of a group must not, however, exceed 5.
Bus cable, for example 0.5 m group
WV = 1.5 + 1.5
0.5 m < 3 m ⇒ group formation ⇒ sum of
the weighting values ≤ 5)
S7-400
W = 1,5
0,5 m
W = 1,5
S7-400