Specifications

LONWORKS® LN-Series Network Communication and Interface Guide Technical Bulletin18
Ground the cable shield using a capacitor to tie the shield to earth ground and use a
large value resistor to bleed off any static charge on the shield.
Tie the shield to earth ground through a capacitor, instead of with a direct
connection. This prevents DC and 50/60 Hz ground paths from forming through
the shield. Typical values for Cc and Rb are as follows:
Cc = 0.1 µF, 10%, Metalized Polyester, ≥ 100 V
Rb = 470 k≥, 1/4 W, ±5%
Ground the cable shield at least once per segment, preferably at each node.
Grounding the shield at every node (using the shield grounding circuit shown in
Figure 12) helps suppress 50/60 Hz standing waves.
Entrance Protection
Use shielded twisted pair wire for networks, or portions of networks, that are run
outside of buildings. Connect the shield to earth at each building entry point via a
data-line lightning/surge arrester to conduct lightning strike energy or power
surges directly to ground and prevent their entry into the building via the control
systems network. Use data-line lightning/surge arresters at each building entrance
and connect them to the network data lines.