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11-26 • E2 RX/BX/CX I&O Manual 026-1614 Rev 4 5-JAN-2013
11.7.3 Applications That May Be
Connected To Zones
There are three different HVAC applications that may
be associated with a Zone application: a MultiFlex RTU
application, a MultiFlex RCB application, and an AHU
application. The MultiFlex RTU and RCB applications
interface with the MultiFlex RTU and RCB I/O Network
boards that control rooftop units. AHU applications use
input and output points on the I/O Network to control air
handling units.
11.7.3.1 MultiFlex RTU Board
The MultiFlex RTU is a control board on the E2’s I/O
Network that controls the operation of a single rooftop
HVAC unit. This board has an on-board processor with
numerous inputs, relay outputs, and 0-10VDC analog out
-
puts, and is designed for controlling advanced rooftop
units with a large number of heat/cool stages, variable-
position economizers, variable-speed fans, etc.
The E2’s MultiFlex RTU applications serve only two
purposes: to act as an interface between the user and the
MultiFlex RTU processor, and to allow communications
between the MultiFlex RTU board and the Zone applica
-
tion. The MultiFlex RTU depends on the Zone application
to provide temperature setpoints, dehumidification and
economization enabling, and other information.
The MultiFlex RTU board also has the ability to act in
stand-alone mode without help from the Zone application.
The MultiFlex RTU has its own fallback temperature con
-
trol strategy, and even has a seven-day fallback occupancy
schedule that may be substituted when communications
with the Zone is lost.
11.7.3.2 MultiFlex RCB Board
The MultiFlex Rooftop Control Board (RCB) (P/N
810-3062) is a rooftop HVAC control board for use either
as a stand-alone controller or in zone control applications
using a Emerson Retail Solutions E2 BX building control
system. The MultiFlex RCB is capable of controlling heat
and cool stages, fans, humidification and dehumidification
devices, economizers using on-board I/O and control algo
-
rithms, as well as monitor and interact with other building
control systems and peripherals (such as smoke alarms and
CO2 sensors).
MultiFlex RCB-P Board
The MultiFlex RCB-P (pulse control board P/N 810-
3076) uses an alternate control strategy that incorporates
logic for controlling the heating and cooling function.
Instead of staging heats or cools On/Off based solely on
the space temperature, the stages follow a pulse modula
-
tion scheme to maintain an average supply temperature,
resulting in smaller space temperature swings and poten
-
tially increasing energy efficiency.
The MultiFlex RCB application must be configured to
communicate with an RCB-P by setting the RCB Type
parameter to Pulse. If the RCB Type parameter is set
incorrectly, Type Mismatch will be shown in the network
summary screen for the device.
Differences Between the MultiFlex RCB and the Mul-
tiflex RTU:
The RCB is an improved version of the MultiFlex
RTU. The RCB has sixteen fully configurable analog and
digital input points, whereas the RTU has only eight
inputs, two of which are configurable. The RCB has four
analog outputs for use in controlling variable speed fans,
economizers or modulating heating and/or cooling valves,
whereas the RTU has only two analog outputs for use only
with VS fans and economizers. The RCB also features a
more sophisticated HHT interface and updated algorithms
for controlling heating, cooling, dehumidification, and air
quality.