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The PIC units can operate either in a stand-alone mode or
they can be interfaced with the Carrier Comfort Network
(CCN). When being installed in network applications, the unit
is connected to the CCN communications bus with field-
installed cable.
Other equipment can also be installed on the CCN by fitting
the equipment with a Comfort Controller Device. The Comfort
Controller Device has a standard processor module (PSIO) but
is field-programmed for use with other HVAC components.
Heating, ventilation and air conditioning (HVAC) and other
building equipment being controlled by PICs or Comfort
Controller Device have the inherent ability to 'talk' on a com-
mon communications bus or network. The configuration of
the communications bus with 2 or more PIC- or Comfort
Controller-controlled pieces of equipment is referred to as a
Carrier Comfort Network (CCN) system. The CCN communi-
cations bus conveys commands, data, and alarms between all
elements of the system. Any system element connected to the
bus may communicate with any other system element, regard-
less of their physical locations. The communications bus con-
sists of a field-supplied, shielded, 3-conductor cable connected
in daisy-chain fashion. The PICs, Comfort Controllers, and
other network devices (such as TELink) can be added at any
time to the network.
The main human interface with the CCN system is the
ComfortWORKS® software. The ComfortWorks software is
installed on an IBM PC compatible computer that allows it to
connect to the communications bus and 'talk' directly with any
equipment connected to the network. An operator working
with ComfortWORKS software can command, monitor, con-
figure, or modify any portion of the system. More than one
computer with ComfortWORKS software can be used. The
computer with ComfortWORKS software, in conjunction with
optional network products, can generate a wide variety of man-
agerial reports which reflect the operational characteristics of
one or more buildings.
To take further advantage of the network, accessory or op-
tional control options modules that perform specialized func-
tions can be added to the communications bus at any time to
enhance the CCN system's capabilities. Each control options
module consists of a standard hardware module with special
purpose algorithms and communications software that provide
an advanced control function for the entire CCN system or a
designated portion of the system. Data collection, remote com-
munications, demand limiting, and tenant billing are a few ex-
amples of the network capabilities available to give the build-
ing owner increased system performance and superior building
management capabilities.
Zoned systems meet the zone temperature control needs for
many commercial applications. These systems utilize a micro-
electronic thermostat as a basis for individual zone control and
typically build multiple-zone systems with constant volume
(CV) or variable-air volume (VAV) units. Zoned systems can
provide complete control of heating and cooling equipment
and zone dampers in many types of HVAC systems.
PIC Rooftop Information —
trols cycle supply-fan motor, compressors, and unloaders to
maintain the proper temperature conditions. The controls also
cycle condenser fans to maintain suitable head pressure. Safe-
ties are continuously monitored to prevent the unit from operat-
ing under abnormal conditions. The controls provide control of
economizer, power exhaust, and inlet guide vane actuators or
variable frequency drives, and cycle or control heating as
required.
A scheduling function, programmed by the user, controls
the unit occupied/unoccupied schedule. The controls also allow
the service person to operate a 'quick test' so that all the con-
trolled components can be checked for proper operation.
The PIC rooftop con-
The PIC controls are modular and use a processor module
(PSIO1), 2 relay modules (DSIO1 and DSIO2), a control op-
tions module (PSIO2), and an accessory field-installed keypad
and display module (HSIO).
Digital Air Volume (DAV) Linkage —
top units with PIC may also have a communication linkage
with the VAV terminal units in a particular application. This
linkage is called the DAV linkage. In order for this linkage to
be possible, the individual VAV air terminals must be equipped
with Carrier PIC controls and the air terminals must be linked
by a Terminal System Manager (TSM). The TSM acts as the
communication link between the VAV air terminal PICs and
the rooftop unit. When the TSM is fully programmed and be-
gins communication, the rooftop control begins using informa-
tion from the TSM for rooftop unit control operation. This is
automatic, and does not require a configuration change to the
standard rooftop unit PIC.
MAJOR CONTROL COMPONENTS
General —
The control system consists of the following
components (see Fig. 2):
• standard processor module (PSIO 8088 or PSIO1)
• control options module (PSIO 8052 or PSIO2) (option
and accessory on sizes 034-074, standard on sizes 078-
104)
• two standard high-voltage relay modules (DSIO1 and
DSIO2)
• keypad and display module (HSIO) (accessory)
• enthalpy sensor
• thermistors (standard and accessory)
• pressure transducers (standard and accessory)
• accessory humidity sensors
• space temperature sensors (standard T-55 and accessory
T-56)
• supply-air fan status switch
• check filter switch
PROCESSOR MODULE NO. 1 (Standard) — The PSIO1
module contains the factory-loaded software that monitors
and processes the following inputs, outputs, and system
information:
Inputs:
• transducers
• thermistors
• switches
Outputs:
• optional integrated economizer motor (4 to 20 mA)
• optional variable frequency drive or inlet guide vane
actuator (4 to 20 mA)
• optional modulating power exhaust control (4 to 20 mA)
• heat stages 1 and 2 operation
• head pressure control, stage 1 (034-078 only)
The PSIO1 module contains a specially-designed battery
that provides power to maintain the module software in
the event of unit power failure. DO NOT remove this
battery, or system software will be lost if there is a unit
power failure.
System Information:
• generates alert and alarm information (via transducer,
thermistor, and sensor inputs)
• supports CCN (Carrier Comfort Network)
communications
• supports digital air volume (DAV) interface
4
Carrier roof-
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