Rockwell Automation Allen-Bradley ControlNet 1786 Series, Installation Instructions Manual

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Publication CNET-IN002A-EN-P - December 2001
2-18 Plan a ControlNet Coax Media System
Inductive loads switched by solid-state output devices alone do not
require surge suppression. However, inductive loads of ac output
modules that are in series or parallel with hard contacts require
surge-suppression to protect the module output circuits as well as to
suppress transient EMI.
Ferrite Beads
Ferrite beads can provide additional suppression of transient EMI.
Fair-Rite Products Corporation manufactures a ferrite bead (part
number 2643626502) which can be slipped over category-2 and
category-3 (RG-6 type trunk cable) conductors. You can secure them
with heat-shrink tubing or tie-wraps. A cable transient EMI induced
onto the cable can be suppressed by a ferrite bead located near the
end of the cable. The ferrite bead will suppress the EMI before it
enters the equipment connected to the end of the cable.
Order Components Now that you are ready to order components, use these guidelines to
help you select components.
Create a General Plan
The ControlNet cable system is isolated from earth and must be
protected from inadvertent ground connections.
Plan Your Segments
•
all connections to the trunk cable require a tap
•
taps may be installed at any location on the trunk cable
•
tap drop-cable length must not be changed
•
maximum number of taps = 48, with 250m (820ft) of standard
RG6 trunk cable
•
maximum number of taps = 48, with 166.6m (546.75ft) of RG6F
high- flex trunk cable
•
maximum trunk-cable length of standard RG6 trunk cable =
1000m (3280 ft), with 2 taps