Rockwell Automation 1786-series ControlNet Fiber Media Planning and Installation Guide - Manual (Page 30)

30 Rockwell Automation Publication CNET-IN001C-EN-P - October 2011
Chapter 2 Topology and Signal Considerations
Coax Segment Constraints The total allowable length of a segment containing standard RG-6 quad shield
coaxial cable depends upon the number of taps in your segment. There is no
minimum trunk-cable section length requirement.
The maximum allowable total length of a segment is 1,000 m (3280 ft) with two
taps connected. Each additional tap decreases the maximum length of the
segment by 16.3 m (53 ft).
The maximum number of taps allowed on a segment is 48, with a maximum
length of 250 m (820 ft).
Figure 11 - Maximum Segment Length (Using 1786-RG6 Coax Cable)
The data in Figure11 assumes you are using standard low-loss coax. High-flex
cable may not support the distance versus the number of taps due to the higher
loss factor associated with high-flex designs.
Example Coax Segment Constraint
For more information in the installation of a coax segment, see publication
CNET-IN002 , ControlNet Coax Media Planning and Installation Guide.
1000 (3280)
750 (2460)
500 (1640)
250 (820)
Maximum Allowable Segment Length =
1000 m (3280 ft) - 16.3 m (53.4 ft) x [number of taps - 2]
Number of Taps
S
eg
m
en
t
Le
ng
th
(f
t)
30014-m
Allowable
Region
2 16 32 64
500 (1640)
EXAMPLE If your segment requires 10 taps, the maximum segment length is:
1000 m (3280 ft) - 16.3 m (53.4 ft) x [10 - 2]
1000 m (3280 ft) - 130.4 m (427.2 ft) = 869.6 m (2852.8 ft)
The total trunk-cable length or number of taps can be increased by
installing repeaters on the segment. This creates another segment.
The amount of high-flex RG-6 cable (catalog number 1786-RG6F) you can
use in a system is less than the amount of standard RG-6 cable, so you
should keep high-flex cable use to a minimum. Use BNC bullet
connectors to isolate areas that require high-flex RG-6 cable from areas
that require standard RG-6 cable; this allows the high-flex RG-6 section
to be replaced before flexture life is exceeded.