Operating instructions

2. How to Install
2.1. Cabling
2.1.1. Cable Lengths and Number of Codes
The maximum cable length allowable in one segment is dependent on the transmission speed.
The total cable length includes drop cables if any. A drop cable is the connection from the main
bus cable to each node if a T-connection is used instead of permissible cable length and maximum
number of nodes/frequency converters with 1, 2, 3 and 4 bus segments.
Drop cable connection (i.e. T-connection) beyond the cable lengths indicated is not recommended,
due to the increased risk of reflection occurring. Instead, Danfoss recommends direct connection
of the frequency converter.
Note that a repeater is a node in both of the two segments it connects. The number of frequency
converters is based on a single master SYSTEM. If there are two or more masters (e.g. PC tools),
the number of frequency converters must be reduced correspondingly.
Maximum total bus cable length:
Transmission speed 1 segment:
32 nodes
(31 VLT)
[m]
2 segments:
64 nodes
(1 repeater, 61 VLT)
[m]
3 segments:
96 nodes
(2 repeaters, 91
VLT)
[m]
4 segments:
128 nodes
(3 repeaters, 121
VLT)
[m]
9.6-187.5 kBaud 1000 2000 3000 4000
500 kBaud 400 800 1200 1600
1.5 Mbaud 200 400 600 800
3-12 MBaud 100 200 300 400
Total drop cable length limit per segment:
Transmission speed Max. drop cable length
per
segment
[m]
9.6-93.75 kBaud 96
187.5 kBaud 75
500 kBaud 30
1.5 Mbaud 10
3-12 MBaud None
VLT
®
Profibus 2. How to Install
MG.33.C4.02 - VLT
®
is a registered Danfoss trademark 13
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