Specifications

59
Modes — The system mode is the highest level mode and
defines three possible states, OFF, RUN and TEST. Below
the RUN mode is the HVAC mode, which includes all the
operational modes of the unit. There are 12 HVAC modes and
one mode will be in effect whenever the unit is in the run mode.
While in one of the HVAC modes, there can be additional
operational modes which may also be displayed in the Scroll-
ing Marquee mode display (see the Table 21).
The Mode or Modes that are in effect will be shown on the
Auto Rotating Display and also in the Mode Level Display.
The structure of the various modes is shown in Fig. 21.
SYSTEM MODE — OFF — When the system mode is off,
all outputs are shut down and no machine control is possible.
The conditions that may cause this mode are in the follow-
ing hierarchical order:
1. Unit commanded off using the STOP software variable
which can be changed using the SERVICE TEST
submenu.
2. Wake up timer on a power reset.
3. Unit Stop (software application level variable that acts as
a hard shut down — UNITSTOP).
4. Fire Shut Down (traumatic fire shutdown condition based
on Fire Shutdown Input (FDWN).
5. CCN Emergency Stop, which is a standard CCN variable
forced over the network through the Emergency Stop
Variable (EMSTOP).
6. Service test ending transition timer.
7. Unexplained internal software.
SYSTEM MODE — TEST — When the system mode is
Test, the software application in the control is constrained
to the Test mode and is controllable via the local displays
(Scrolling Marquee and Navigator) or through the factory
service test control. See the Test Mode section for details on
test control in this mode.
SYSTEM MODE — RUN — When the system mode is Run,
the software application in the control is free to run the HVAC
control routines by which cooling, heating, IAQ, etc., is possible.
HVAC MODE — The HVAC mode is reliant on the system
mode to further qualify the operational control state. There are
12 HVAC modes.
The determination of the HVAC mode is based the opera-
tion conditions of the unit.
Mode 0 — HVAC_OFF
— The unit is off as a result of a fire
shutdown input or a remote Start Stop switch input. The status
of the fire input can be check on the INPUT-SW.IN submenu
through the Fire Shutdown Input (SW.IN).
If the Remote Switch configuration (RMT.C), which is
found in the CONFIGURATION-OPTS submenu, is set to 2
(START STOP) then the remote switch (RE.MT) can be used
to remotely start and stop the unit. This particular configuration
forces the system down but honors compressor timeguards.
Mode 1 — HVAC_TEST
— The unit is in the self test mode
which is entered through the SERVICE TEST menu.
Mode 2 — HVAC_VENT
— This is a normal operation
mode where no heating or cooling is required and just outside
air is being delivered to the space to control IAQ levels.
Mode 3 — HVAC_COOL
— This is a normal cooling mode
where a high cooling demand is being required.
Mode 4 — HVAC_LOCL
— This is a normal cooling mode
where low cooling demand is being required.
Mode 5 — HVAC_UEFC
— In this mode the unit will be
operating in cooling but will be using the economizer for free
cooling. Entering this mode will depend on the status of the
outside air. The unit can be configured for outside air change
over, differential dry bulb changeover, outside air enthalpy
changeover, differential enthalpy changeover, or a custom
arrangement of enthalpy/dewpoint and dry bulb. See the
Economizer section for further details.
Mode 6 — HVAC_HEAT
— The unit will be in low heating
demand mode using either gas heat or electric heat.
Mode 7 — HVAC_HTHI
— The unit will be in the high heat-
ing demand mode using either gas heat or electric heat.
Mode 8 — HVAC_FIRE
— The unit has been stopped due to
a fire input (SW.IN) and then one of fire control modes, purge,
evacuation, or pressurization has been evoked based on the
remote switch inputs.
Mode 9 — HVAC_PRES
— The unit is in the special fire
pressurization mode where the supply fan is on, the econo-
mizer damper is open and the power exhaust fans are off. This
mode is invoked by the Fire Pressurization (F.PRS) input
which can be found in the INPUT-SW.IN submenu.
Mode 10 — HVAC_EVAC
— The unit is in the special fire
evacuation mode where the supply fan is off, the economizer
damper is closed and the power exhaust fans are on. This mode
is invoked by the Fire Evacuation (F.EVC) input which can be
found in the INPUT-SW.IN submenu.
Mode 11 — HVAC_PURG
— The unit is in the special fire
purge mode where the supply fan is on, the economizer
damper is open and the power exhaust fans are on. This mode
is invoked by the Fire Evacuation (F.PRG) input which can be
found in the INPUT-SW.IN submenu.
System Mode
Run Mode
Off Mode Test Mode
HVAC Mode
HVAC_OFF (0)
Unit off mode
HVAC_TEST (1)
In Test mode
HVAC_VENT (2)
In Vent Mode
HVAC_COOL (3)
In High Cool Mode
HVAC_LOCL (4)
In Low Cool Mode
HVAC UEFC (5)
In Free Cool Mode
HVAC_HEAT (6)
Low Heat Mode
HVAC_HTHI (7)
Low Heat Mode
HVAC_FIRE (8)
Fire Shutdown
HVAC_PRES (9)
Pressurization Mode
HVAC_EVAC (10)
Evacuation Mode
HVAC_PURG (11)
Purge Mode
Fig. 21 — Operating Modes