Carrier 50FC A04 Series, Service And Maintenance Instructions, Page: 29 / 112

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RTU OPEN CONTROL SYSTEM
The RTU Open controller is an integrated component of the
Carrier rooftop unit. Its internal application programming pro-
vides optimum performance and energy efficiency. RTU Open
enables the unit to run in 100% stand-alone control mode, Car-
rier’s i-Vu ® Open network, or a Third Party Building Automa-
tion System (BAS). On-board DIP switches allow the user to
select your protocol (and baud rate) of choice among the four
most popular protocols in use today: BACnet, Modbus 1 , John-
son N2 and LonWorks 2 . See Fig. 52.
The RTU Open control is factory-mounted in the unit’s main
control box, to the left of the UCB (unit control board). Factory
wiring is completed through harnesses connected to the UCB.
Field connections for RTU Open sensors will be made at the
PCB connectors on the RTU Open board. The factory-installed
RTU Open control includes the supply-air temperature (SAT)
sensor. The outdoor air temperature (OAT) sensor is included
in the FIOP/accessory EconoMi$er ® 2 package.
Sensory/Accessory Installation
There are a variety of sensors and accessories available for the
RTU Open. Some of these can be factory or field installed,
while others are only field installable. The RTU Open control-
ler may also require connection to a building network system
or building zoning system. All field control wiring that con-
nects to the RTU Open must be routed through the raceway
built into the corner post of the unit or secured to the unit con-
trol box with electrical conduit. The unit raceway provides the
UL required clearance between high and low-voltage wiring.
Pass the control wires through the hole provided in the corner
post, then feed the wires thorough the raceway to the RTU
Open. Connect the wires to the removable PCB connectors and
then reconnect the connectors to the board.
Fig. 52 — RTU Open Control Module
1. LonWorks is a registered trademark of Echelon Corporation.
2. Modbus is a registered trademark of Schneider Electric.
IMPORTANT: Refer to the specific sensor or accessory
instructions for its proper installation and for rooftop unit
installation refer to base unit installation instructions and the
unit’s wiring diagrams.
WARNING
ELECTRICAL SHOCK HAZARD
Failure to follow this warning could result in personal inju-
ry, death and/or equipment damage.
Disconnect and lockout/tagout electrical power before wir-
ing the RTU Open controller.
J4
J2 J1
J5 J5
J22
J17
J19
J14
J11
J22
J3
J13
J12
J15
J20
Network Comm
Configurable - Input_8
24 V
A
C
Configurable - Input_5
24 V
A
C
Configurable - Input_3
24 V
A
C
Input_9 (Humidistat)
24 V
A
C
24 V
A
C
Input _8 (Enthalpy)
AO-1 (ECON)
Gnd
(OA
T
)
Gnd
(SA
T)
Input_5 (SMK) Input_4
(R)
BO-5
(Y1)
BO-4
(Y2)
BO-3
(W1)
BO-2
(W2)
BO-1
(G)
Gnd Input_3
(X)
24 V
AC IN
+24 VDC
Input_2 (CO2/RH)
Gnd
+24 VDC
Input_1 (CO2/RH)
Gnd
Board Power
(AO-1)
0-10VDC
4-20mA
BO-6
(H) Humidimizer
BO-8
(Power Exhaust)
LonWorks
Option Card
Port
Example set for
BACnet MS/TP
and 76.8K baud
(1, 2, and 4 ON)
Recommended for all
i-Vu Open installations
Protocol Selector SPT (temp input) BACnet, Modbus, or N2
(LON connection J15) SPT (common)
SPT (offset input)
*Remove
both for 0-5V
AO-2
GND
(2-10V)
3-Volt
Lithium
Battery
BO-1 BO-2 BO-3 BO-4 BO-5
BO-6
BO-7
BO-8
VAF Output