MG.90.A2.02 – VLT is a registered Danfoss trademark
6
FCM 300 PROFIBUS / VLT 2800 PROFIBUS
The total drop cable length for one segment is limited
as stated in the table below.
Drop cable length
Max. drop cable
length per segment
Transmission speed
[m]
9.6-93.75 kBaud
96
187.5 kBaud
75
500 kBaud
30
1.5 MBaud
10
3 MBaud
none
The length statements in the tables above are valid
provided that bus cable with the following properties
is used:
-
Impedance:
135 to 165 ohm
at a measuring frequency from 3 to
20 MHz
-
Resistance:
<
110 ohm/km
-
Capacity:
<
30 pF/m
-
Damping:
max. 9 dB over the whole wire
length
-
Cross section: max. 0.34 mm
2
,
corresponding to AWG 22
-
Cable type:
twisted in pairs,
1 x 2, or 2 x 2, or 1 x 4 wires
-
Screening:
Copper-braided screen
or braided screen and foil screen
It is recommended to use the same cable type in the
entire network to avoid impedance mismatch.
The numbers on the following drawing indicate the
maximum number of stations in each segment. They
are not the station addresses as each station in the
network must have a unique address.
The PROFIBUS Interface
Segment 3
Segment 1
Segment 2
Segment 4
Rt = termination
resistors
