Omron PROFIBUS DP GATEWAY Operation Manual page 47

Setting up a PROFIBUS Network
Cable Type
Maximum PROFIBUS
Cable Length
32
two devices in the network. The following figure presents an example of a net-
work with more than three segments and repeaters.
Max. 31 stations
M / S
Segment 4
Max. 31 stations
M / S
M / S Master or slave station
Repeater
R
Termination
Max. total number of stations = 126
The PROFIBUS standard EN 50170 specifies Type A shielded, twisted- pair
cable as the recommended cable type for use in an RS-485 based PROFI-
BUS network. This cable type has the following characteristics:
Impedance
Capacitance per unit length
Loop resistance
Core diameter
Core cross section
Note The PROFIBUS standard EN 50170 also specifies a Type B cable with slightly
different cable characteristics. This Type B cable is no longer recommended
for use.
The transmission speed defines the maximum advised cable distance or
cable segment in metres before the use of a repeater is recommended. The
cable lengths specified in the following table are based on PROFIBUS type A
cable.
Baud rate
(kbit/s)
9.6
19.2
45.45
93.75
187.5
Segment 1
Segment 3
R
Max. 28 stations
R
Segment 5
Max. 30 stations
Characteristic
Distance/segment
(m)
1200
1200
1200
1200
1000
Section 2-5
Segment 2
Max. 31 stations
M / S
R
M / S
R
M / S
R
Segment 6
Max. 31 stations
M / S
Value
135 - 165 ohms
< 30 pF/m
110 ohms/km
0.64 mm
2
0.34 mm
Baud rate Distance/segment
(kbit/s) (m)
500 400
1500 200
3000 100
6000 100
12000 100