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D20/D200 Technical Overview
F. D.20 Link Installation
Guidelines for Installing a D.20 Link
Some considerations to note when installing peripherals remotely are as follows:
Transceiver Cable (RS-485)
• The maximum distance, for the communication portion (i.e. TX and RX), of the D.20 Link,
from the D20 termination panel to the Termination Resistor, is 1000 ft (300 m).
• Repeater modules may be used to extend the D.20 Link beyond the maximum distance. The
DCI can extend this limit by 1000 ft.
• The limit for the power supply portion (+DC & -DC) of the D.20 Link depends on the
loading. This, in turn, is determined by the following factors:
− Number of peripherals per remote location
− Maximum load of each peripheral (see D. Power Consumption – D20 Modules)
− IR drop on the cable
• Cable losses for typical RS-485 wire gauges are:
− #22 AWG [0.644mm] wire = .016 ohms/ft
− #20 AWG [0.812mm] wire = .010 ohms/ft
• Ensure that the lower threshold of 20 V, on each peripheral, is met.
• WESDAC Power Converters, rated at 20 W/125 V in, 24 or 48 V out, may be used for a
maximum of two peripheral modules.
• To minimize the IR drop of the cable, a higher supply voltage (i.e. 48 V) for peripherals is
recommended. An auxiliary power supply, rated at 100 W/125 V DC in, 48 V DC out, may
be used.
Fiber Optic Cable
• At the start of the fiber optic cable (D20 end), the following items are required:
− D20 fiber optic transceiver, either a 1:1 (DCI) or a 1:4 (DFS), depending on the number
of peripheral locations
− Glass (GFO) or plastic (PFO) fiber optic adaptors, as required
• Remote D20 peripheral I/O modules require 20 to 60 V DC source. A WESDAC Power
Converter or Power Supply may be used for 125 V input sites.
• The recommended maximum distance for fiber optic cable is:
− Glass: 6500 ft / 2000 m
− Plastic: 146 ft / 45 m
Repeater modules may be used to extend beyond this limit.
94
PRPI-019-3.00-10
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