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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HSTIE Usage
The number of High Speed Trunk Isolator Extenders (HSTIEs) on a logical RS-485
ALN or a logical FLN trunk is directly related to the total trunk length, type of trunk wire
used, and the time delay allowed by the network protocol. Trunk cabling causes bit
distortion that limits the total trunk length to the distances listed in table Distance per
2-wire Trunk Section.
Since the HSTIE re-times the packet bytes, the maximum amount of trunk a network
can support has increased. The HSTIE introduces a delay limiting the number that can
be used in series. Do not exceed the HSTIE usage limits shown in table Speed vs.
Maximum Number of HSTIEs in Series.
Speed vs. Maximum Number of HSTIEs in Series.
Speed
1200 bps 4800 bps 9600 bps through 115,200 bps
ALN only 10 6 6
FLN only N/A 6 6
RS-485 ALN and FLN (P1) Communications
Wiring on Structured Cabling
NOTE:
The Insight Server and Client, APOGEE Ethernet Microserver (AEM), and other field
panels operating Ethernet protocols do not use the chained patch cables referred to
in this section. These devices must be plugged into an operational TCP/IP network
using standard Ethernet patch cables.
Installation
The Structured Cable System (SCS) is installed per industry standards in a star
distribution topology. This does not comply with the RS-485 wiring system used for
HVAC or most other building automation systems (BAS). Special patch cables or
punch down cables at each end of a wiring segment are used to convert the star
topology to multi-drop trunk topology. The wiring segments and patch cables are
individually certified. Once plugged in, the wiring segments and patch cables must be
certified as an ALN or FLN.
CAUTION
Unplugging a patch cable from a structured cabling system will split the multi-
drop trunk and disconnect part of the RS-485 ALN or FLN (P1) from the BAS.