41
NOTE: If D.F.ON is configured below DAQ.H, the unit is in
occupied mode, and the fan was off, then DAQ rose above
D.F.ON and the fan came on, the economizer will go to the
economizer minimum position (EC.MN).
The 4 to 20 mA signal from the sensor wired to TB201-8
and TB201-7 is scaled to an equivalent indoor CO
2
(IAQ) by
the parameters IQ.R.L and IQ.R.H located under the Configu-
ration
IAQ
AQ.SR menu. The parameters are defined such
that 4 mA = IQ.R.L and 20 mA = IQ.R.H. When the differen-
tial air quality DAQ (IAQ – OAQ.U) exceeds the DAQ.H set
point (Configuration
IAQ
AQ.SP menu) and the supply
fan is on, the economizer minimum vent position (Configura-
tion
IAQ
DCV.C
EC.MN) is overridden and the damper
is moved to the IQ.P.O configuration. When the DAQ falls be-
low the DAQ.L set point (Configuration
IAQ
AQ.SP
menu), the economizer damper is moved back to the minimum
vent position (EC.MN).
NOTE: Configuration OAQ.U is used in the calculation of the
trip point for override and can be found under Configura-
tion
IAQ
AQ.SP.
IQ.A.C
= 3 (4 to 20 mA Damper Control) — This configura-
tion will provide full 4 to 20 mA remotely controlled analog in-
put for economizer minimum damper position. The 4 to 20 mA
signal is connected to terminals TB201-8 and TB201-7. The
input is processed as 4 mA = 0% and 20 mA = 100%, thereby
giving complete range control of the effective minimum
position.
The economizer sequences can be disabled by unpluging
the enthalpy switch input and not enabling any other econo-
mizer changeover sequence at Configura-
tion
ECON
E.SEL. Complete control of the economizer
damper position is then possible by using a 4 to 20 mA econo-
mizer minimum position control or a 0 to 10,000-ohm 0 to
100% economizer minimum position control via configuration
decisions at Configuration
IAQ
AQ.CF
IQ.A.C.
To disable the standard enthalpy control input function,
unplug the enthalpy switch and provide a jumper from TB201-
6 to TB201-5 (see wiring diagrams in Major System Compo-
nents section on page 127).
IQ.A.C
= 4 (10,000 ohm Potentiometer Damper Control)
— This configuration will provide input for a 10,000 ohm lin-
ear potentiometer that acts as a remotely controlled analog in-
put for economizer minimum damper position. The input is
processed as 0 ohms = 0% and 10,000 ohms = 100%, thereby
giving complete range control of the effective minimum
position.
NOTE: For complete economizer control, the user can make
the economizer inactive by unplugging the enthalpy switch
connection.
CONTROLS OPERATION
Modes —
The ComfortLink controls operate under a hierar-
chy of command structure as defined by three essential ele-
ments: the System mode, the HVAC mode and the Control
mode. The System mode is the top level mode that defines three
essential states for the control system: OFF, RUN and TEST.
The HVAC mode is the functional level underneath the
System mode which further defines the operation of the
control.
The Control mode is essentially the control type of the unit
(Configuration
UNIT
C.TYP). This defines from where
the control looks to establish a cooling or heating mode.
Furthermore, there are a number of modes which operate
concurrently when the unit is running. The operating modes of
the control are located at the local displays under Operating
Modes. See Table 24.
Currently Occupied (
OCC) — This variable displays the cur-
rent occupancy state of the unit.
Timed Override in Effect (
T.OVR ) — This variable displays
if the state of occupancy is currently occupied due to an
override.
DCV Resetting Minimum Position (
DCV) — This variable
displays if the economizer position has been lowered from its
maximum vent position due to demand control ventilation.
Supply Air Reset (
SA.R) — This variable displays if the sup-
ply air set point that the rooftop is attempting to maintain is
currently being reset upwards. This applies to cooling only.
Table 24 — Operating Modes Display Table
Demand Limit in Effect (
DMD.L) — This variable displays
if the mechanical cooling capacity is currently being limited or
reduced by a third party.
Temperature Compensated Start (
T.C.ST) — This variable
displays if Heating or Cooling has been initiated before occu-
pancy to pre-condition the space.
IAQ Pre-Occupancy Purge Active (
IAQ.P) — This variable
displays if the economizer is open and the fan is on to pre-
ventilate the building before occupancy.
Linkage Active CCN (
LINK) — This variable displays if a
linkage master in a zoning system has established “linkage”
with this air source (rooftop).
Mechanical Cooling Locked Out (
LOCK) — This variable
displays if mechanical cooling is currently being locked out
due to low outside air temperature.
HVAC Mode Numerical Form (
H.NUM) — This is a numer-
ical representation of the HVAC modes which may be read via
a point read.
SYSTEM MODES (Operating Modes
SYS.M)
System Mode Off
— When the system mode is OFF, all out-
puts are to be shut down and no machine control is possible.
The following list displays the text assigned to the System
Mode when in the OFF mode and the conditions that may
cause this mode are checked in the following hierarchal order:
1. Wake up timer on a power reset.
(“Initializing System ...”)
2. System in the process of shutting down compressors and
waiting for timeguards to expire.
(“Shutting Down ...”)
3. Factory shut down (internal factory control level —
SHUTDOWN).
(“Factory Shut Down”)
4. Unit Stop (software application level variable that acts as
a hard shut down — Service Test
STOP).
(“Local Machine Stop”)
5. Fire Shut Down (fire shutdown condition based on the
Fire Shutdown Input (Inputs
FIRE
FSD).
(“Fire-Shutdown Mode”)
ITEM EXPANSION RANGE CCN POINT
SYS.M ascii string n/a
HVAC ascii string n/a
CTRL ascii string n/a
MODE MODES CONTROLLING UNIT
OCC Currently Occupied ON/OFF MODEOCCP
T.OVR Timed Override in Effect ON/OFF MODETOVR
DCV DCV Resetting Min Pos ON/OFF MODEADCV
SA.R Supply Air Reset ON/OFF MODESARS
DMD.L Demand Limit in Effect ON/OFF MODEDMLT
T.C.ST Temp.Compensated Start ON/OFF MODETCST
IAQ.P IAQ Pre-Occ Purge Active ON/OFF MODEIQPG
LINK Linkage Active — CCN ON/OFF MODELINK
LOCK Mech.Cooling Locked Out ON/OFF MODELOCK
H.NUM HVAC Mode Numerical Form number MODEHVAC
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