User`s guide

4-4 Network Cabling and

Connection

System Performance and Cable Selection

TP/FT-10 network system and transmission specifications are outlined on the

following pages. Both of these specifications must be met to ensure proper

operation.

The system designer may choose a variety of cables, depending on cost,

availability, and performance. Performance may vary with cable type. The

transmission specification depends on such factors as resistance, mutual

capacitance, and the velocity of propagation. Currently, Echelon has documented

system performance on the cable types shown in table 4.1.

Table 4.1 Cable Types and Typical Parameters

Cable Type Wire

dia./AWG

loop

Ω/km

nF/km

Vprop

% of c

Belden 85102, single twisted pair,

stranded 19/29, unshielded, 150°C

1.3mm/16 28 56 62

Belden 8471, single twisted pair,

stranded 19/29, unshielded, 60°C

1.3mm/16 28 72 55

Level IV 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

TIA568A Category 5 24AWG, twisted

pair

0.51mm/24 168 46 58

If a shielded cable is used, the shield should be connected to earth ground via a

470kΩ, 1/4 Ωatt, ≤10%, metal film resistor to prevent static charge build-up. See

[17] for more information on Level IV cable.

Note that the following specifications are for one network segment.

Multiple segments may be combined using repeaters as described in

chapters 1 and 2 to increase the number of nodes and distance.

System Specifications

• Up to 64 FTT-10/FTT-10A transceivers are allowed per network segment.

• LPT-10 transceivers may be used on network segments with FTT-10/FTT-10A

transceivers, but are subject to additional constraints, particularly on

distance. See the LPT-10 User's Guide for more information.

• The average temperature of the wire must not exceed +55°C, although

individual segments of wire may be as hot as +85°C.