5-4 Network Cabling and System Performance
System Performance and Cable Selection
Link power performance has system, transmission, and power specifications which are outlined
on the following pages. Each of the specifications should be met to ensure proper operation.
The system designer may choose a variety of cables, depending on cost, availability and
performance. Performance as outlined in the transmission and power specifications varies with
cable type. The wire resistance per unit length is a significant factor in the power specification,
since the system is designed to accommodate a substantial drop in voltage along the wire
according to Ohm's Law. The transmission specification depends on such factors as resistance,
mutual capacitance, and the velocity of signal propagation.
Echelon has characterized system performance on several cable types whose typical electrical
parameters are shown in table 5.1.
Table 5.1
Cable Parameters
Cable Type
Wire dia.
/AWG
Rloop
Ω
/km
C
nF/km
Vprop
% of c
Belden 85102, single twisted pair,
stranded 9/29, unshielded, plenum
1.3mm/16
28 56 62
Belden 8471, single twisted pair,
stranded 9/29, unshielded, nonplenum
1.3mm/16
28 72 55
Level 4/22AWG, twisted pair,
typically solid & unshielded
0.65mm/22 106 49
67
JY (St) Y 2x2x0.8, 4-wire helical twist,
solid, shielded
0.8
mm/20.4
73 98 41
Category 5, UTP, EIA/TIA 568A
0.5mm/24
168
50
58
If the cable has a shield, it should be connected to the LPI-10 module ground (at the P1 connector)
via a 470k
Ω
, 1/4 Watt,
≤
10%, metal film resistor to prevent static charge build-up.
For more information on Level 4 cable, go to the Underwriters Laboratories Inc. website at
www.ul.com.
Note that the specifications in
Transmission Specifications
are for one network segment. Multiple
segments may be combined using repeaters as described in Appendix A to increase the number of
devices, application current, and distance. For example, a free topology network containing 256
link power devices and total wire length of up to 500 meters may be built using two segments
interconnected by a repeater, assuming network traffic requirements are met. See limitations in
Appendix A.
