CMVPFB01A 6
Installation
3.3 Electrical Installation
3.3.1 Cable Types
Due to the high data rates used on PROFIBUS-DP networks it is paramount that correctly specified quality
cable is used. The use of low quality cable will result in excess signal attenuation and data loss. Cable
specifications and approved manufacturers are available from the official PROFIBUS website at: http://
www.profibus.com
3.3.2 Network Limitations
There are several limiting factors that must be taken into consideration when designing a PROFIBUS-
DP network, for full details refer to the official “Installation Guidelines for PROFIBUS-DP/FMS” which is
available from http://www.profibus.com. However, here is a simple checklist:
PROFIBUS-DP networks are limited to a maximum of 125 nodes.
Only 32 nodes may be connected on a single network segment.
A network may be built up from one or several segments with the use of network repeaters.
Maximum total network length is governed by the data rate used. Refer to Table 3.
Minimum of 1 meter of cable between nodes.
Use fiber optic segments to:
Extend networks beyond normal cable limitations.
Overcome different ground potential problems.
Overcome very high electromagnetic interference.
Spurs or T connections are only acceptable by the PROFIBUS-DP specification when operating at data
rates of 1.5Mbps or less, however it is strongly advised not to use spurs as extreme care must be taken
during the network design phase to avoid problems.
Table 3: Standard “Type A” Cable Network Length Specifications
Baud Rate Maximum Segment Length Recommended Maximum Total Network Length
9.6kbps 1200 meters 6000 meters
19.2kbps 1200 meters 6000 meters
45.45kbps 1200 meters 6000 meters
93.75kbps 1200 meters 6000 meters
187.5kbps 1000 meters 5000 meters
500kbps 400 meters 2000 meters
1.5Mbps 200 meters 1000 meters
3Mbps 100 meters 500 meters
6Mbps 100 meters 500 meters
12Mbps 100 meters 500 meters
NOTE
The recommended maximum network length is achievable with the use of repeaters.
Due to signal propagation delay within the repeaters it is recommended that no
more than 4 repeaters be used between any two network nodes
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