Rockwell Automation 1770 DH,DHII,DH485 CABLE - Manual (Page 84)

Planning a DH II Cable System
Chapter 5
5-8
The trunkline on your network is divided into several segments by taps.
The cable length of the trunkline is equal to the total cable length of the
trunkline segments.
Important: When determining the cable length of trunkline segments, be sure
to measure the actual cable path as it is routed in your network. Be sure to
consider vertical dimensions as well as horizontal dimensions. You should
always calculate the three-dimensional path distance when determining
cable lengths.
How you configure your network determines the lengths of all trunkline
segments.
Important: Remember that the maximum cable length of the trunkline is 8,000
feet (2440 meters), and that each node on the trunkline reduces the 8,000 feet
(2440 meters) of available cable by 75 feet (22.9).
Also remember that cable segments must be at least 30 feet (9.2 meters) in
length between taps.
You should also plan your trunkline cable routing so that the cable bend-radius
is not less than 6 inches (15.2 cm).
Figure 5.5
The bendĆradius for the trunkline cable should not be less than 6 inches
(15.2 cm).
6 inch
12642
Guidelines for Determining
Cable Length