The SmartCommand thermostat (model CC-SCSTAT) provides typical thermostat functions as well as the
capability to send and receive information via serial communications. This capability allows the thermostat's
setpoint, mode, and fan operation to be changed remotely. In addition, the remote systems can request status of
the thermostat's temperature, setpoints, modes, and other system information.
The thermostat consists of two parts, a wall display unit (WDU) and a HVAC control unit. The wall display
unit looks like a traditional thermostat and is the wall-mounted user interface for the control unit. It provides a
display screen, control buttons, and the temperature sensor. The wall display unit connects to the control unit
by a four-wire cable. The control unit connects to the HVAC system in place of a standard thermostat and
provides thermostatic control of the system. In addition, the control unit sends and receives data and
commands via a twisted-pair serial communication connection for remote control of the system. The control
unit can be used with up to three remote temperature sensors.
Wall display unit (WDU)
The WDU has a backlit LCD graphical display capable of both text and graphics, control buttons, LEDs, and a
digital temperature sensor. The unit can display multiple screens. In the default Thermostat control screen
(Figure 1) it shows the current temperature, setpoints, mode and manual fan mode, time, outside temperature
and other information.
Figure 1. Wall display unit default screen
Any changes in temperature, or control button operations, are transmitted to the control unit. Updates are
received from the control unit and displayed by the WDU.
WDU control buttons
Both the four control buttons and the up and down buttons on the WDU change functions when you change
screens. The function of the buttons is defined by on-screen labels that are dynamic and change when you