Choose connectors, Decide whether to use redundant media – Rockwell Automation 1786-series ControlNet Coax Media Planning and Installation Guide User Manual
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Publication CNET-IN002B-EN-P - June 2010
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Plan a ControlNet Coax Media System Chapter 2
Choose Connectors
There are BNC, TNC, and FLEX Ex connectors and adapters available to
meet your system requirements. For descriptions and illustrations of these
components, see the ControlNet Media System Components List,
publication
Decide Whether to Use
Redundant Media
You can run a second trunk cable between your ControlNet nodes for cable
. Media redundancy is achieved by installing devices with
redundant ports and installing a second cabling system. In the event of a cable
failure or degraded cabling, the redundant network is used by the system.
Trunk cables on a redundant cable link are defined by the segment number and
the redundant trunk-cable letter. Actual ControlNet products are labeled with
these icons
(the shaded icon representing redundant media).
In the illustration (on
), the nodes support redundant media and the
redundant cable trunk cable is trunk cable B.
When configured for redundant cabling, all nodes will simultaneously transmit
and receive on both channel A and channel B. There is no distinction on the
network between packets on channel A and channel B. Each node will
independently decide which channel, A or B, it will listen to; this is based on
historical counters that are internal to each node.
There is no overall network parameter that says which channel to use, each
node decides on its own. At any time, whether a network has valid or invalid
redundant cabling, there can be a mix of which channel any node is listening
to; some nodes could be listening on channel A and some could be listening
on channel B.
When planning a redundant media system, route the two trunk cables
(A and B) such that damage to one cable will not damage the other cable to
reduce the chance of both cables being damaged at the same time. Also be
certain that both cables’ routing is similar in distance and duplicate nodes for
proper redundant cable operation.
IMPORTANT
If you are installing a bullet connector for future tap
installations, count the bullet as one of the tap allotments on
your segment and decrease the maximum allowable cable
length by 16.3 m (53.4 ft). This helps you avoid reconfiguring
your network when you install the tap.
IMPORTANT
Redundant cabling can tolerate one or more faults on a single
channel. If a fault were to occur on both channels, the network
operation would be unpredictable.