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OUTPUT SCALING
The CO
2
output signal is scaled such that 4-20 mA (or 0-5 / 0-10 Vdc) equals 0-2000 ppm by default. The
signal span may be changed via the Setup Menu from 1000 to 10,000 ppm in 500 ppm increments.
START-UP MODE
Verify the device is properly wired and connections are tight. Ensure the mA / VOLT switch is set for the
correct signal type. Apply power and the LCD will indicate the software version number, the output signal
type and then the sensor will begin a one minute warm-up countdown. When the warm-up time expires
the device will enter normal mode.
NORMAL MODE
The sensor will begin reading the CO
2
level (and temperature if it is installed), output the correct analog
signal and display the values on the LCD. If the relay is installed, the measurements will be compared to
the setpoint and appropriate action taken. The keypad is monitored and if the <MENU> key is pressed the
device will enter the Setup Menu. The Setup Menu can be accessed to configure the device for required
operation.
RELAY MODE
The optional relay can be used as an alarm signal to indicate that a setpoint has been exceeded. For
the basic CO
2
product, the relay may be configured via the Setup Menu as a high or low alarm and the
setpoint value, hysteresis and on-delay time may be set. The relay will activate and close the contacts if
the CO
2
measurement goes above the setpoint (for a high alarm) or below the setpoint (for a low alarm).
If required, this action can be delayed by a time period (relay delay time) to prevent false alarms. After the
relay is activated, the measurement must fall below the setpoint - hysteresis value (for a high alarm) or go
above the se hysteresis value (for a low alarm) to deactivate the relay and open the contacts. The
high/low assignment, setpoint, delay time and hysteresis values may all be programmed via the Setup
Menu as required.
If the optional temperature sensor is installed, the relay operation may be assigned to operate as a
temperature high or low alarm instead of a CO
2
alarm. All the same relay parameters may be configured
to set up the alarm as required.
SETUP MENU
The device has several parameters that can be configured locally via the Setup menu using the keypad
and LCD. Any changes made are saved in non-volatile memory and are restored in case of a power loss. The
menu can be accessed at any time after the start-up mode and if there is 5 minutes of inactivity the menu
will close and normal operation will continue.
To enter the menu, press and release the <MENU> key. This will enter the Setup Menu step 1, pressing the
<MENU> key a second time saves the setting and advances to step 2. Each press of the <MENU> key saves
the current setting and advances the menu item. The <UP> and <DOWN> keys are used to make changes
to program variables by scrolling through the available options. The first column below shows what will
be displayed on the LCD, including the default value.
<MENU>
Press and release the <MENU> key to enter the Setup Menu
CO2 Span
2000 ppm
Self-Cal
ON
The CO
2
Span value controls the analog output scaling. CO
2
span can be changed
from 1000 to 10,000 ppm in 500 ppm increments using <UP> or <DOWN>. If CO
2
Span = 2000 ppm, then the output signal is scaled 0-2000 ppm = 4-20 mA. Factory
default is 2000 ppm.
The Self-Cal feature <MENU> when enabled requires the sensor to be exposed
to fresh air for at least one hour every twenty-four hours. When first installed the
sensor requires a minimum of seven days of operation with fresh air exposer daily
to allow the algorithm to adjust for self-calibration. Default for device is having this
feature disabled enabled “ON". If disabling this feature a manual calibration should
be performed to ensure accuracy of the device.
<MENU>
Press to advance to next menu item
<MENU>
Press to advance to next menu item
1. SPAN
2. SELF-CALIBRATION
The optional relay output connects to the RELAY terminals. The relay output is completely isolated and
has a Normally Open (NO) signal. This signal can be used to directly control an alarm or ventilation fan. See
specifications for contact ratings. See Figure 8.
The optional two-wire temperature sensor output is available with various RTDs and thermistors to suit all
control applications and is available on the TEMP terminals. See Figure 9.
Copyright © Greystone Energy Systems, Inc. All Rights Reserved Phone: +1 506 853 3057 Web: www.greystoneenergy.com
IN-GE-CD2DTXXX-03
