34
Wire the controllers on an MS/TP network segment in a dai-
sy-chain configuration. Wire specifications for the cable are
22 AWG (American Wire Gage) or 24 AWG, low-capacitance,
twisted, stranded, shielded copper wire. The maximum length
is 2000 ft.
Install a BT485 terminator on the first and last controller on
a network segment to add bias and prevent signal distortions
due to echoing. See Fig. 35-37.
To wire the UPC Open controller to the BAS network:
1. Pull the screw terminal connector from the controller's
BAS Port.
2. Check the communications wiring for shorts and
grounds.
3. Connect the communications wiring to the BAS port’s
screw terminals labeled Net +, Net -, and Shield.
NOTE: Use the same polarity throughout the network
segment.
4. Insert the power screw terminal connector into the UPC
Open controller's power terminals if they are not current-
ly connected.
5. Verify communication with the network by viewing a
module status report. To perform a module status report
using the BACview keypad/display unit, press and hold
the “FN” key then press the “.” Key.
To install a BT485 terminator, push the BT485 terminator
on to the BT485 connector located near the BACnet connector.
NOTE: The BT485 terminator has no polarity associated with
it.
To order a BT485 terminator, consult Commercial Products
i-Vu
®
 Open Control System Master Prices.
MS/TP WIRING RECOMMENDATIONS  — Recommen-
dations are shown in Tables 11 and 12. The wire jacket and UL
temperature rating specifications list two acceptable alterna-
tives. The Halar specification has a higher temperature rating
and a tougher outer jacket than the SmokeGard specification,
and it is appropriate for use in applications where the user is
concerned about abrasion. The Halar jacket is also less likely to
crack in extremely low temperatures. 
NOTE:  Use the specified type of wire and cable for maximum
signal integrity.
Table 11 — Open System Wiring Specifications and Recommended Vendors 
                            LEGEND
31.25” 
INSIDE 
RA 
97.78” (027-050), 150.47” (060)
INSIDE DIMENSION 
Fig. 34 — Side Return Air Conversion
a48-8371
WIRING SPECIFICATIONS  RECOMMENDED VENDORS AND PART NUMBERS
      Wire Type     Description 
Connect Air
International
Belden RMCORP
    Contractors
Wire and Cable
MS/TP
Network (RS-485)
22 AWG, single twisted shielded pair, low capacitance, CL2P, 
TC foam FEP, plenum rated. See MS/TP Installation Guide for 
specifications. 
W221P-22227 — 25160PV CLP0520LC
24 AWG, single twisted shielded pair, low capacitance, CL2P, 
TC foam FEP, plenum rated. See MS/TP Installation Guide
for specifications. 
W241P-2000F 82841 25120-OR —
Rnet  4 conductor, unshielded, CMP, 18 AWG, plenum rated.  W184C-2099BLB 6302UE 21450 CLP0442
AWG — American Wire Gage
CL2P — Class 2 Plenum Cable
CMP — Communications Plenum Rated
FEP — Fluorinated Ethylene Polymer
TC — Tinned Copper