Specifications
D) Controller Lights (LEDs)
The controller is equipped with 3 LEDs that are green (closest to edge of controller), yellow, and red
(closest to center of controller).
(1) Green - Power and Data Transmission LED. If this light is off, check controller power. Under
operation conditions, this light should flicker or be ON. This light will flicker when data is being
transmitted onto the communications network.
(2) Yellow - Data Reception LED. This light will flicker when data is being received from the
communications network.
(3) Red - Service LED. This light will flicker when a controller is being programmed over the network.
If the light steadily blinks at the rate of once per second, the controller is not programmed. Contact
the factory for a replacement controller.
If this light remains ON, the controller has detected an internal error and requires service. Remove
controller power for 15 seconds, and then restore power. If the LED remains ON, check the
controller power supply (nominal 24 VAC across terminals 24H and 24G). If the LED remains ON,
turn off the unit and replace the controller.
4) Standard Inputs
The following inputs are the digital (binary) inputs used with the controller. Some items are optional and
others are used only with specific control packages. Please see Section 6 for details on the unit sequence of
operation.
A) Water Coil Low Limit
This input is attached to the coil used on all units with steam or water. A low limit switch is connected in
parallel with the outdoor air temperature sensor (OAT). When the low limit switch closes, it short circuits
the OAT sensor input, thus initiating low limit mode.
B) Occupancy Input
If the unit is connected to a LON network and the network occupancy input is bound to an occupancy
controller, the network initiates occupied/unoccupied modes, regardless of the status of the physical
occupancy input. Without a network, all units use controller digital input 1 (DI1, terminal #26) for the
occupancy status input. When terminal DI1 is connected (input switch closed) to a common terminal
(COM, #22), the controller switches to unoccupied mode, unless the unoccupied override button on the
dual-mount thermostat is pressed. When terminal DI1 is disconnected from COM, the unit enters
occupied mode.
This input may be factory connected to an optional day/night relay, where the relay coil must be field
wired to an occupancy controller. This relay is factory wired so that the relay is energized for unoccupied
mode and de-energized for occupied mode. When ordered, this relay is mounted on the control panel.
This input may be factory connected to an optional 7-day timeclock. This timeclock has an override
switch (holiday switch) built into the clock face that can be used to force the unit into occupied or
unoccupied modes. When ordered, this timeclock is mounted on the control panel.
C) Change-over Input
This input is used only on 2-pipe, systems with chilled water. A changeover switch (aquastat) is
connected between controller terminals DI2 (#24) and COM (#25). The switch contacts close when the
switch senses that the water temperature is below 65°F, thus indicating that chilled water is available
and initiating cooling mode. The unit enters heating mode when the contacts open at 85°F.
D) Refrigerant Low Limit
This input is used with DX coils on self-contained unit ventilators. A low limit switch is connected
between controller terminals DI2 (#24) and COM (#25). The switch contacts close when the DX coil
temperature falls below 28°F, thus prompting the controller to disable the compressor.
5) Standard Outputs
Some output items are optional and others are used only with specific control packages. Please see Section
6 for details on the unit sequence of operation.
A) Outdoor Air / Return Air Damper Actuator
This actuator is connected to 24 VAC power and is controlled with a 4-20 mA signal from Analog Output
1 (AO1, #23). The actuator will close the outdoor air damper on a power failure. A 4 mA signal drives
the damper fully closed, while a 20 mA signal drives the actuator to full open position.
7/1/03 Part Number 011-200001-003 Page 7