WAGO I/O SYSTEM 750 XTR
Fieldbus Communication 129
750-333/040-000 FC PROFIBUS G2 12MBd XTR
Manual
Version 1.4.0
PROFIBUS User Organization
The PROFIBUS User Organization makes documents about PROFIBUS
available on its web site:
- Technical descriptions
- Directives
10.1.1
Cabling
On PROFIBUS with RS-485 transmission technology, all devices are connected
in a linear topology. The bus line consists of a twisted and shielded core pair.
The fieldbus cable is specified as cable type A in IEC 61158 and must exhibit
certain performance parameters. The cable type B also described in IEC 61158
is obsolete and should no longer be used.
Table 80: Technical Data, Bus Line
Parameter
Value
Wave impedance
135
… 165 Ω
Effective capacitance
< 30 pF/m
Loop resistance
110
Ω/km
Core diameter
*)
> 0.64 mm
Core cross-section
*)
> 0.34 mm
2
*)
The core cross-sections used must correspond to the connection options on the bus connector.
The maximum cable lengths result with cable type A for a bus segment
depending on the transfer rate.
Table 81: Transfer Rate
Transfer rate
max. fieldbus segment length
9.6 / 19.2 / 45.45 / 93.75
kBaud
1200 m
187.5
kBaud
1000 m
500
kBaud
400 m
1500
kBaud
200 m
3000 / 6000 / 12000
kBaud
100 m
The 750-960, 750-970 fieldbus connectors offered by WAGO make it possible to
connect the coming and going data cable to the connector directly. In this way,
branch lines are avoided and the bus connector can plug in and unplug at without
having to interrupt data traffic to the bus. A reversible bus terminator is integrated
in these connectors. Due to the capacitive load of the bus node and the
generated line reflection, connectors with integrated length inductances should
be used. This is essential for transfer rates of > 1.5 Mbaud.