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
•
•
•
•
•
•
•
•
•
•