Omron GRT1 - 27-11-2006 Operation Manual page 44

Setting up a PROFIBUS Network
Cable Type
Maximum PROFIBUS
Cable Length
Stub Lines
Segment 1
Max. 31 stations
M / S
Segment 4
Max. 31 stations
M / S
M / S
Master or slave station
R
Repeater
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:
Characteristic
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 differ-
ent cable characteristics. Use of Type B cable is no longer recommended.
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
Note If network extension beyond the range of the advised cable length is required,
the use of fibre optic cable to cross the larger distance should be considered.
Passive Stub lines (branches from the main line) should be avoided for data
transmission speeds of more than 500 kbit/s. Except at end devices with ter-
mination, it is recommended to always use plug connectors that permit two
Max. 31 stations
Segment 3
R
Max. 28 stations
R
R
Segment 5
M / S
Max. 30 stations
R
Max. 31 stations
Distance/segment Baud rate
(m)
1200
1200
1200
1200
1000
Section 2-4
Segment 2
M / S
R
M / S
Segment 6
M / S
Value
135 - 165 ohms
< 30 pF/m
110 ohms/km
0.64 mm
2
0.34 mm
Distance/segment
(kbit/s) (m)
500 400
1500 200
3000 100
6000 100
12000 100
25