Rockwell Automation Allen-Bradley ControlNet 1734-ACNR User Manual page 171

The amount of high-flex RG-6 cable you can use in a system is less than the
amount of standard RG-6 cable due to higher attenuation, 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.
An allowable total length of RG-6 flex cable segment in your application can
be determined using the equation below. Each additional tap decreases the
maximum length of the segment. The maximum number of taps allowed on a
segment is 48. Each additional tap decreases the maximum length of the
segment by different lengths depending on the attenuation of your high-flex
cable.
Maximum Allowable Segment Length of Cable =
Cable attenuation is defined as the signal loss measured at 10 MHz per 1000 ft
(304 m) of cable.
EXAMPLE
(1)
1786-RG6F/B cable has an attenuation of 13.5 db/1000 ft at 10 MHz. 1786-RG6 cable has an attenuation of
5.99 db/1000 ft at 10 MHz.
Determine Your ControlNet Media Requirements
(20.29 db - [Number of Taps in Segment * .32 db])
Cable Attenuation @ 10 MHz Per 304 m (1000 ft)
If your segment requires 3 taps using 1786-RG6F/B
cable, the maximum segment length is:
(20.29 db - [3 X.32 db]) / (13.5 db/1000)
(19.33 db) / (13.5 db/1000) = 1431.8 ft (436 m)
Publication CNET-UM001C-EN-P - November 2005
C-9
(1)