Engineering Documentation

Table Of Contents
Chapter 2 Network Electrical Systems
RS-485 ALN and FLN (P1) Communications Wiring on Structured Cabling
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Riser Segment Length
The Telecommunications (wiring) Closet-to-riser interface will generally be Category 5
riser cable on new installations. Following information systems standards, basic link
cable runs are limited to 600 ft (190 m) of solid copper terminated by punch down
blocks in the main and intermediate wiring closets.
SCS segments are wired per TIA 568A (preferred) or 568B. Observing the 600 ft (190
m) restriction allows future conversion to Ethernet devices in the field panel without
rewiring the SCS segment. See the following table for RS-485 ALN and FLN pinout.
The Figure Punching Down the Riser Cabling for an RS-485 ALN or FLN shows
incoming cable punch down in an intermediate wiring closet from a main wiring closet.
Wiring Procedure for ALN and FLN (P1) on Structured Cabling.
Wiring Block
Position
Device Connection Conductor Pair
Color
Signal Path RJ45 TIA568A
(Preferred)
1 + White-Blue Outgoing RS-485 ALN or FLN 5
2 Blue 4
3 + White-Orange Incoming RS-485 ALN or FLN 3
4 Orange 6
5 Not used White-Green Second outgoing signal pair or initiating device
(contact closure)
1
6 Not used Green 2
7 Not used White-Brown Second incoming signal pair or indication device (4-
20 mA)
7
8 Not used Brown 8
Fig. 28: Punching Down the Riser Cabling for an RS-485 ALN or FLN.