Echelon Series 6000 Chip databook - Manual (Page 109)

Ca and Cb are typically aluminum-electrolytic type for improved longevity in the presence of
ESD. Be sure to observe their polarity.
Grounding Shielded Twisted Pair Cable
When using shielded twisted-pair cable, terminate the twisted pair and ground the cable
shield, as shown in Figure 42.
Figure 42. Shielded Twisted-Pair Termination and Grounding
Use the termination described in Free Topology Network Segment or in Doubly Terminated
Bus Topology Segment. The cable shield should be grounded using a capacitor to tie the
shield to earth ground, and a large-value resistor to bleed off any static charge on the shield.
Tie the shield to earth ground through a capacitor, instead of using a direct connection, to
avoid DC and 50/60 Hz ground paths from being formed through the shield. Typical values
for Rb and Cc are:
• Cc = 0.1 μF, 10%, Metalized Polyester, ≥ 100V
• Rb = 470 kΩ, 1/4 W, ±5%
The cable shield should be grounded at least once per segment, and preferably at each device.
Grounding the shield at every device assists in suppressing 50/60 Hz standing waves.
Series 6000 Chip Data Book 97