CTI 2500-RIO-B Installation and Operation Guide V1.4
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CTI recommends Beldon 3105A cable for wiring remote I/O. The following table contains the
general recommended cable specs for RS485 remote I/O wiring and the preferred Beldon cable type
specifications.
Cable Characteristic
Recommended
Belden® 3105A
Conductors
18AWG to 22AWG uniform
twisted-pair
2-conductors,22AWG,.030
in (7.5mm), 7x30 stranded
Shielding
100% shield coverage
100% coverage with 90%
copper braid plus drain wire
Characteristic
Impedance
100 Ω to 150 Ω
120 Ω
Capacitance
< 50 pF/m
11 pF/ft (36 pF/m)
DC Resistance
Resistance of installed length
< characteristic impedance
14.7 Ω/1000 ft (48.2 Ω/km)
Attenuation
< 1.0 dB/100 ft
(1.0 dB/ 30 m)
0.5 dB/100 ft (0.5 db/30 m)
@ 1MHz
Velocity of
Propagation
> 65%
78%
Operating Temperature
0 to +60 ºC
-20 to +60 ºC
2.3 Specify Cable Type
Based on your topology selection and distances, specify the cable type to be used based on the
information included below. The following cables (or equivalent) are acceptable for use for remote
I/O connections.
Alternative Cable Specs
Belden
Cable Type
Outside
Diameter
Impedance
Capacitance
Velocity
Center
Conductor
3105A
.281 in
7.1 mm
120 ohm
36 pf/m
0.78c
22 AWG 7x30
48.2 ohm/km
9182
0.35 in.
8.9 mm
150 ohm
28.9 pf/m
0.78c
22 AWG 19x34
46 ohm/km
9271
0.24 in
6.1 mm
124 ohms
40 pf/m
0.66c
25 AWG 7x33
104.3 ohm/km
9860
0.44 in.
11.2.mm
124 ohms
35.8 pf/m
0.78c
16 AWG Solid
13.8.ohm/km
Belden 9182 and 3105A are suitable for intermediate length trunk lines. These cables cannot be
intermixed with other cables for trunk lines. In addition, if either of these cables are used for a trunk
line, they must also be used for all drop lines. They may also be used for drop lines with Belden
9860 or Belden 9271 trunk lines.
