Operation - Distech Controls GS-AQR Hardware Installation Manual

secondary of an AC transformer or when wiring multiple devices to
ensure that the circuit ground point is the same on all devices and the
controller.
Figure 9: Typical AC or DC wiring
Ensure the controller Analog Input (AI) matches the IAQ voltage output
signal type before power is applied. The voltage signals have a
minimum load rating. Follow the ratings in the Specification section or
inaccurate readings may result.
Linear Output
Connect the LINEAR output signal to a 0-5 or 0-10 VDC analog input
port on the controller as shown in Figure 9. The device is factory
configured for 0-5 VDC output signal but may be changed to 0-10 VDC
via the menu. Changing output signal may be done during set up of the
device. This linear output signal represents the 0-2000 ppm CO
equivalent value.
Analog Stepped Output
The ASO (Analog Stepped Output) output signal is a second voltage
signal that represents the three air quality levels of GOOD, FAIR and
POOR. Each level may be set independently via the menu to any value
between 0 and 10 VDC. The factory default is GOOD = 2.5 V, FAIR =
5.0 V and POOR = 7.5 V. This signal can also be connected to a
controller analog input, or it can be connected directly to a 0-5 or 0-10
VDC input of a damper actuator for direct ventilation control as shown
in Figure 10. In this way, the Indoor Air Quality Sensor can be used as
a stand-alone device. Since all steps are completely adjustable, the
device can also drive a reverse acting actuator.
Figure 10: Direct connection to a damper actuator.
Override Switch Output
The optional override switch output is a digital output signal that is
controlled by the front panel override button. The signal is available on
the OVERRIDE terminal and will short the OVERRIDE terminal to
COMMON when activated as shown in Figure 11.
This signal typically connects to a low voltage digital input of the
controller to indicate room occupancy or override when the button is
pressed. This output uses a FET to create the pull-down to common so
respect the device ratings.
Figure 11: Override terminal connection.
Resistive Temperature Sensor
An optional resistive temperature sensor may also be included in the
device and is connected to the TEMP terminals as shown in Figure 12.
Various thermistors or RTDs may be installed on the pcb to suit the
application. These terminals would connect to a thermistor or RTD
sensor input on the controller.
Figure 12: Resistive temperature sensor.
Relay Output
Another optional signal is the relay output available on the RELAY
terminals. The relay output terminals are completely isolated from
other connections and are NOT connected to the signal COMMON
terminal as shown in Figure 13. This signal can be used to directly
control an alarm, a ventilation fan or may be connected to a digital
input of the Building Automation System for status monitoring. Respect
the relay contact specification.
Figure 13: Relay output.
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Start-up
2
Verify that the Air Quality Sensor is properly wired and all connections
are tight. Apply power to the device and note that the LCD will display
the software version number for a few seconds and then the device will
enter Warm Up mode. The Warm Up mode will last for five minutes
and the LCD will count down the time. The status LED will cycle
through the three colors (green / red / blue). This time is required to
allow the device and sensor to reach normal operating temperature.
After the five minutes has expired the device will enter normal
operation and the LCD will indicate the IAQ status and ppm value.

Operation

In normal operation, the Air Quality Sensor will detect a broad range of
reducing gases such as CO and VOCs and translate the measurement
into a parts per million (ppm) CO
displayed on the LCD in either ppm or % as set in the menu. The air
quality value is also displayed as GOOD, FAIR or POOR and these
values can also be set via the menu.
The GOOD, FAIR and POOR air quality levels control the Analog
Stepped Output (ASO) signal. The ASO output signal comprises of
three independently set voltage levels that can be used to directly
control a damper actuator for three positions. The levels are set via the
menu and each level can be set anywhere from 0-10 Vdc. The GOOD,
FAIR and POOR air quality levels will also be displayed on the tri-color
front panel LED. The LED colors are displayed as GOOD = green,
FAIR = blue and POOR = red. If required, the LED operation can be
disabled via the menu.
The air quality value is also sent to the LINEAR output as a 0-5 or 0-10
Vdc signal to represent the 0-2000 ppm CO
can interface to any voltage analog input for logging or control
purposes.
The linear output scaling and ASO operation are shown in Table 1 and
Table 2. Note that the ASO GOOD/FAIR trip level = 1000 ppm and the
FAIR/POOR trip level = 1500 ppm. The ASO output levels are GOOD
= 2.5 V, FAIR = 5.0 V and POOR = 7.5 V.
equivalent value. This value is
2
equivalent. This signal
2
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