Honeywell AUTOMATIC CONTROL SI Edition, Engineering Manual

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ENGINEERING MANUAL OF AUTOMATIC CONTROL
BUILDING MANAGEMENT SYSTEM FUNDAMENTALS
186
Facilities management system configuration must deal with
two levels of operation: day-to-day operations and long-range
management and planning. Day-to-day operations require a
real-time system for constant monitoring and control of the
environment and facility. The management and planning level
requires data and reports that show long-range trends and
progress against operational goals. Therefore, the primary
objective of the management and planning level is to collect
historical data, process it, and present the data in a usable format.
The development of two-wire transmission systems, PCs for
centralized functions, and distributed processors including
DDC led to a need to define system configurations. These
configurations became based on the needs of the building
and the requirements of the management and operating
personnel. Typical configurations are discussed in SYSTEM
CONFIGURATIONS.
SYSTEM CONFIGURATIONS
A BMS includes the hardware configuration and
communication systems needed to access data throughout a
building or from remote buildings using leased telephone lines.
HARDWARE CONFIGURATION
Microprocessor-based controllers have led to a hierarchical
configuration in the BMS. Figure 1 shows several levels, or
tiers, of processors.
— Management-level processors
— Operations-level processors
— System-level controllers
— Zone-level controllers
The actual levels used in a given system depend on the specific
needs of the building or complex of buildings. The zone level
may incorporate intelligent, microprocessor-based sensors
and actuators. The discussions that follow begin with zone-
level controllers.
ZONE-LEVEL CONTROLLERS
Zone-level controllers are microprocessor-based controllers
that provide direct digital control of zone-level equipment,
including items such as VAV boxes, heat pumps, single-zone
air handlers, and perimeter radiation. Energy management
software can also be resident in the zone-level controller. At
the zone level, sensors and actuators interface directly with the
controlled equipment. A communications bus provides
networking of zone-level controllers so that point information
can be shared between zone-level controllers and with
processors at the system and operation level. Zone-level
controllers typically have a port or communications channel
for use of a portable terminal during initial setup and
subsequent adjustments.
PERIPHERAL
DEVICES
MANAGEMENT-LEVEL
PROCESSORS
OPERATIONS-LEVEL
PROCESSORS
SYSTEM-LEVEL
CONTROLLERS
ZONE-LEVEL
CONTROLLERS
AND INTELLIGENT
SENSORS AND
ACTUATORS
TO
SENSORS
AND
ACTUATORS
PERIPHERAL
ETHERNET LAN
DEVICES
SENSOR
ACTUATOR
TO
SENSORS
AND
ACTUATORS
TO
SENSORS
AND
ACTUATORS
TO
SENSORS
AND
ACTUATORS
PC TYPE
COMPUTER
PC OR
MINICOMPUTER
C1855
PC TYPE
COMPUTER
MC MC MC MC MC MC
MC
MC
MC
MC
MC
MC
T
Fig. 1. Hierarchical BMS Configuration.