Lenze 931K - Manual (Page 13)

Electrical installation
Wiring
4
l
13 KHB 13.0004−EN 2.1
Baud rates
Baud rate [kbps] Length of the transmission cable [m]
9.6 ... 93.75 1200
187.5 1000
500 400
1500 200
3000 100
6000 100
12000 100
)
Note!
ƒ The baud rate depends on the data volume, cycle time and number of bus
stations.
ƒ The baud rate selected should be as low as possible. The lower the baud
rate, the more insensitive the PROFIBUS is to parasitic coupling.
I
Tip!
For high baud rates, we recommend to consider the application of optical
fibres.
Advantages of optical fibres:
ƒ External electromagnetic interferences have no effects on the transmission
path.
ƒ Bus lengths of several kilometres are also possible with higher baud rates.
The bus length is
– independent of the baud rate.
– depend on the optical fibre used.
Specification of the transmission cable
Please follow the specifications of the PROFIBUS user organisation (PUO) for signal cables:
Bus cable specification
Specific resistance 135 − 165 W/km, (f = 3 − 20 MHz)
Capacitance per unit length £ 30 nF/km
Loop resistance < 110 W/km
Core diameter > 0.64 mm
Core cross−section > 0.34 mm 2
Cores Double twisted, insulated and shielded