Emerson E2 Applications That May Be Connected To Zones, MultiFlex RTU Board, MultiFlex RCB Board

11.7.3Applications 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.

11.7.3.1MultiFlex 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.

11.7.3.2MultiFlex 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.

11-26 • E2 RX/BX/CX I&O Manual 026-1614 Rev 4 5-JAN-2013