FD67 Profibus-DP Manual
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3.1.5 Baud rate
All the devices in a Profibus network use the same baud rate set by the bus master. It is automatically
recognized by the FD67 bus node.
According to the selected baud rate, the max. admissible cable lengths must be observed (see Table 3-1
below). These values relate to a single bus segment. By using repeaters, it is possible to achieve greater
network extensions over several segments.
Baud rate in kBit/s
9,6
19,2
45,45 93,75 187,5 500
1500 3000 6000 12000
Cable length in m
1200 1200 1200 1200 1000 400
200
100
100
100
♦
Table 3-1 : Max. admissible cable lengths in a Profibus segment
3.1.6 Address
Profibus user addresses range from from 0 to 125. The two address switches of the FD67 bus node allow
to set addresses from 0 to 99.
It is important to ensure that an explicit and unique address is assigned to each Profibus user. The
Profibus address is set directly at the FD67 bus node via two BCD switches that are integrated into to the
base module.
The set address is read in once after a voltage reset. A change of address in operation is not supported.
Detailed information can be found in the FD67 System manual.
3.1.7 Spur lines
As a rule, passive spur lines should be avoided.
If spur lines are required, e.g. for temporary connection to programming or diagnostic devices, use active
spur lines or repeaters. Correct termination must always be assured.
3.1.8 Design guidelines
Design guidelines have been issued by the Profibus User Organization (PNO). They must be strictly
observed, as well as the information contained in the FD67 manuals. See the PNO homepage :
www.profibus.com