SenseAir aSENSE User manual

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UMA0139
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7
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1 (6)
CO2/ temperature transmitter
General
The IAQ-sensor product aSENSE is used to measure indoor air carbon dioxide concentration and
temperature in rooms. The aSENSE is available both with and without display, (LCD). Both are
available for wall mounting as well as for duct mounting.
The unit is designed for connecting to Direct Digital Control (DDC). The linear output functions are pre-
programmed as CO2 and temperature transmitters with jumper selected outputs 0-10 V / 2-10 V / 0-
20 mA / 4-20 mA. The measuring ranges can be modified from a PC (Windows NT, XP, 7) and use of
the software UIP (version 5 or higher) together with the RS232 communication cable.
Figure 1 aSENSE for wall mounting and duct mounting
aSENSE
User Manual

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UMA0139
Rev
7
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2 (6)
Sensor outputs
Terminal
Default Output
Default Output
Range
Outputs of this
sensor
Output Range of this
sensor
Out(1)
0-10VDC
0-2000 ppm CO2
See label
See label
Out(2)
0-10VDC
0-50 oC
32-122 oF
See label
See label
Table I. Default output configurations for aSENSE
Formulas for calculation of output values
Configuration
Output Range
Formula for calculation
0─10 VDC
0─2000ppm CO2
0─50oC
32─122oF
CO2value = Volt/10*2000
Temperature value in oC = Volt/10*50 = Volt*5
Temperature value in oF = Volt*9+32
2-10 VDC
0─2000ppm CO2
0─50oC
32─12oF
CO2value = (Volt –2)/8*2000
Temperature value in oC = (Volt –2)/8*50
Temperature value in oF = (Volt –2)/8*(122-32)+32
4-20 mA
0─2000 ppm CO2
0─50oC
32─122oF
CO2value = (mA-4)*2000/16
Temperature value in oC = (mA-4)*50/16
Temperature value in oF = (mA-4)/16*(122─32)+32
a-b
c–d
Value = (reading-a)/(b-a)*(d-c)+c
a = lowest value of the configuration
b = highest value of the configuration
c = lowest value of the range
d = highest value of the range
Table 2. Calculation of CO2value and temperature value for aSENSE
Output Configurations
The sensors/controllers are supplied from the factory (unless otherwise ordered) with 0...10VDC linear
outputs for Out(1) and Out(2) (see Table I). If other options are needed for the application, the output
jumpers have to be configured before the unit is powered up. Each jumper selection is independent
from the others, except for the “Start point selection” jumper, which affects both Out(1) and Out(2)
linear outputs. Alternative measuring ranges of the outputs can be selected with the software UIP
(version 5 or later).

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UMA0139
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Outputs Configuration
Jumper
Position
Function
Start
point
selection
jumper
0%
20%
Jumper top position provides 0Vdc or 0mA start point for Out(1), Out(2)
Jumper bottom position provides the start point given by the file. The start
point can be reconfigured with the UIP
Out(1)
Current
Voltage
Connection in position “Current” provides 0/4─20mA output range for Out(1).
Current output is not recommended for temperature measurements
Connection in position “Voltage” provides 0/2─10VDC output range for Out(1).
Please note! Temperature measurements accuracy is valid only for units
configured in voltage outputs mode.
Out(2)
Current
Voltage
Connection in position “Current” provides 0/4─20mA output range for Out(2).
Current output is not recommended for temperature measurements
Connection in position “Voltage” provides 0/2─10VDC output range for Out(2).
Please note! Temperature measurements accuracy is valid only for units
configured in voltage outputs mode.
Table 3. Configuration jumpers for aSENSE
Self-diagnostics
The system contains complete self-diagnostic procedures. A full system test is executed automatically
every time the power is turned on. In addition, constantly during operation, the sensor probes are
checked against failure by checking the valid dynamic measurement ranges. All EEPROM updates,
initiated by the sensor itself, as well as by external connections, are checked by subsequent memory
read back and data comparisons. These different system checks return error bytes to the system
RAM. The error codes are available by connecting a PC with a special RS232 cable connected to the
UART port slide connector. The error codes are shown in the software UIP (version 5 or later). Warm
up and Out of Range are the only bits that are reset automatically after return to normal state. All other
error bits have to be reset manually after return to normal by power off/on.
The yellow LED lights yellow at heating phase after power up and if an error has been detected.

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UMA0139
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Error code and action plan
Bit #
Error
code
Error description
Suggested action
0
N/A
Fatal Error
Try to restart sensor by power OFF/ON.
Contact local distributor
1
2
Reserved
2
4
Algorithm Error.
Indicate wrong EEPROM
configuration.
Try to restart sensor by power OFF/ON.
Check detailed settings and configuration
with UIP software version 5 and higher.
Contact local distributor.
3
8
Output Error
Detected errors during output signals
calculation and generation.
Check connections and loads of outputs.
Check detailed status of outputs with UIP
software version 5 and higher.
4
16
Self-Diagnostic Error.
Algorithm timeout
Check detailed self-diagnostic status with
UIP software version 5 and higher.
Contact local distributor
5
32
Out of Range Error
Accompanies most of other errors.
Resets automatically after source of
error disappearance.
Try sensor in fresh air.
Check connections of temperature and
relative humidity probe.
Check detailed status of measurements
with UIP software version 5 and higher.
See Note 1!
6
64
Memory Error
Non-fatal error during memory
operations.
Check detailed settings and configuration
with UIP software version 5 and higher.
7
128
Warm Up state
Is always set after power up or power
failure. Resets after restart sequence.
If it doesn’t disappear in half a minute,
check power stability.
Table 4 Error codes
Note 1.Any probe is out of range. It occurs, for instance, during over exposure of CO2sensor, in
which case the error code will automatically reset when the measurement values return to normal. It
could also indicate the need of zero point calibration. If the CO2readings are normal, and still the error
code remains, the temperature sensor can be defect or the connections to it are broken.
Remark:If several errors are detected at the same time the different error code numbers will be
added together into one single error code!
PLEASE NOTE! The sensor accuracy is defined at continuous operation (at least three (3) ABC
periods after installation)
Maintenance
aSENSE is basically maintenance free. An internal self-adjusting calibration function takes care of
normal long term drift associated to the CO2sensor. To secure the highest accuracy, a time interval of
five years is recommended between CO2calibrations, unless some special situations have occurred.
A zero calibration can be performed by use of pure nitrogen or air that has passed through a chemical
absorber and a PC together with the UIP software version 5 (or higher) or by shortening of holes
marked in figure 2 for at least 10 seconds. The sensor needs stable gas flow for at least 3 minutes
before zero calibration. The Zero Calibration bag can be used to produce carbon dioxide free air. The
software can be free downloaded from www.senseair.com. The RS232-cable and the zero calibration
bag can be ordered from SenseAir. The cable is to be connected to the UART port slide connector
(see Fig. 5). For change of control parameters and re-calibration of temperature this PC tool has to be
used. Zero calibration can be done with PC and UIP software version 5 or by shorting marked holes in
figure 2. The check can be done on site without interfering with the ventilation system.

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A Back-ground calibration is an easy way to correct a sensor’s zero point. The sensor needs fresh air
(380-420 ppm CO2). Shorten holes marked in figure 2 for at least 10 seconds.
This is for sensors with measuring ranges between 0-3000 ppm and 0-4%:
When a zero calibration shall be executed a plastic tube with 2.2 mm outer diameter and 0.8 mm inner
diameter shall be inserted in marked holes of the sensor. Plastic tubing is connected to the tube. The
gas flow should be between 0.3 and 1.0 l/min. The sensor needs stable gas flow for at least 3 minutes
before zero calibration. Shorten marked holes for at least 10 seconds. A successful calibration is
acknowledged by 5 flashes of the yellow LED. If unsuccessful, please release input and waits at least
10 seconds before repeating the procedure again. Make sure that the sensor environment is steady
and calm!
Gas inlet
Figure 2 Part of the PCB with holes for gas inlets marked.
Duct mounting
If for some reason the printed circuit board (PCB) needs to be removed, special precaution must be
taken in order not to damage the temperature probe in the sampling tube. When putting the PCB back
in the protective housing, the probe must be gently positioned in the sampling tube.
Figure 3 aSENSE printed circuit board

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Figure 4 The aSENSE for duct mounting. The temperature probe is the black body in the sampling tube.
+
~
Figure 5 Terminals and jumpers on aSENSE.The darker positions are default settings. The start point jumper is not mounted on
some models.
Senseair®AB (headquarter)
Stationsgatan
Box 96
820 60 Delsbo
SWEDEN
Phone: +46-(0)653 - 71 77 70
E-mail: [e-mail]
Web site: www.senseair.com