3 Network Topologies
3.3 Star topology
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Version 04 05/2014
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Ensure that the electrical star segment is wired
carefully. Keep it as small as possible to avoid
interference injection into the electrical star
segment, and from here into the entire network.
This can be achieved by laying out the OZD Profi
12M … PRO in the electrical star segment directly
next to each other on a hat rail.
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Switch on the terminating resistors in the bus port
connectors (see 4.8, ”Connecting the electric RS
485 bus lines“, p. 30) at both ends of the electrical
star segment.
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Do not connect a bus subscriber to the electrical
star segment wherever possible.
Repeaters with one or two optical channels can be used
to create an active PROFIBUS star coupler. Repeaters
with one optical channel are sufficient for connecting a
terminal or an RS 485 bus segment to the active star
coupler.
If the link monitoring on the optical channels is activated,
the fiber optic links are monitored by the respectively
connected OZD Profi 12M … PRO.
Note:
Optical channels which are not assigned (for instance,
because they are reserved for a future system extension)
indicate a fiber break if the link monitoring is activated.
You can prevent this error report from being issued by
activating the operating mode ”Line without fiber link
monitoring“ at the non-assigned channels.
Please note that optical channels which are not connected
must always be fitted with protective caps to guard
against extraneous light and dirt.