Allen-Bradley 1779-KFMR User Manual page 29

Chapter 3
Installing Cabling Hardware for
the Data Highway II Link
3 6
You can calculate the length limit (in cable-feet) for the trunkline cable
with the formula:
Trunkline Length = 8,000 - (No. of Local Taps x 75)
For example, if your link requires 24 taps, the trunkline length is limited
to 6,200 cable-feet. If your link requires only five taps, the trunkline
length can be up to 7,625 cable-feet. Figure 3.6 shows the relationship of
trunkline length to the number of nodes using local taps.
Figure 3.6
Length of Trunkline Allowed for Number of Local Taps
10K
8K
6K
Length of
Trunkline
in Feet
4K
2K
Bend Radius of Cables
If you bend a coaxial cable sharper than the recommended minimum bend
radius, you may decrease the reliability of the link.
Plan your trunkline cable routing so that the cable will have no sharper
bend than a minimum 6-inch bend radius (Figure 3.7).
20 40 60
Number of Nodes with Local Taps
80 100 120