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LNL-1000 Intelligent System Controller
Direct-connect RS-232 cables should be no longer than 50 feet. Leased lines or fiber optics can also be used.
For RS-485 communication, the following type of RS-485 cable is required: 24 AWG (minimum) twisted
pair (with shields.) Either 2-wire or 4-wire RS-485 cable configuration can be used. The RS-485 cable
should be no longer than 4000 feet (1219 m), 100 ohms maximum (Belden 9842 4-wire or 9841 2-wire,
plenum cabling Belden 88102, West Penn, or equivalent.) The drop cables (to readers and other devices)
should be kept as short as possible, no longer than 10 feet.
RS-232 Communications
The RS-232 communications interface is for short distance wiring or point to point communications. A
number of products provide RS-232 interfaces such as connections to local printer, modem, PC, etc. This
interface is intended for a short distance communication because its high impedance is more susceptible to
noise. Cable length is generally limited to 50 feet (15.24 m). If required, this distance may be extended to a
few hundred feet by using low capacitance shielded cables. The optimal cable is a (Belden 9610) or
equivalent wire.
RS-485 Communications
The (EIA) Electronic Industries Association standard defines RS-485 as an electrical interface for multiport
communications on a bus transmission line. It allows for high-speed data transfer over extended distance
(4000 feet, 1219 m). The RS-485 interface uses a balance of differential transmitter/receiver to reject
common mode noise. For increased reliability over the extended distances End-of-line (EOL) termination is
required.
RS-485 Line Termination
RS-485 (2-wire or 4-wire) must be terminated at both ends of the RS-485 line (bus). Terminating the line
provides a more reliable communication by minimizing the signal reflection and external noise coupling.
Each has an on-board terminator. It is up to the installer to determine which device is at the End of the
communication line (see diagram).
Belden (24 gauge wire – (7x32) Stranded Conductors – Polyethylene Insulated)
Trade Number
Numbe
UL NEC Type
r of
CSA
Pairs
Certification
9841
1
NEC CM CSA
9842
2
NEC CM CSA
80 —
revision 7
Belden Wire Specifications
Nominal
Shield
D.C. R.
Conductor
24.0 ohms/M
3.35 ohms/M
78.7 ohms/
11.0 ohms/K
km
24.0 ohms/M
2.2 ohms/M
78.7 ohms/
7.2 ohms/K
km
Nominal
Nominal
Impedance
Capacitance
(Ohms)
pF/feet
120
12.8
120
12.8
pF/
meter
42
42
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