10
5.3. Carbon dioxide concentration measurement
A multiple point CO2 and temperature adjustment procedure leads to excellent CO2 measurement
accuracy over the entire temperature working range; this is a must for process control and outdoor
applications. The dual wavelength NDIR CO2 sensing procedure compensates automatically for
ageing effects. The CO2 module is highly resistant to pollution and offers maintenance free operation
and outstanding long term stability. Measured values can be read in „SLOW mode“ (filtered,
averaged) or in „FAST mode“ (current values without averaging). SLOW mode has advantages in
applications like climate control because of filtering short time peaks. As an example exhaled air
from an employee passing the sensor could affect the climate control negatively with a short response
time because the control would trigger a change of the ventilation based on this one-time
measurement. On the contrary in „FAST mode“ no software filter is used for calculating the output
value. This fact adds a noise of typ. ±30ppm which has to be considered in terms of accuracy. Of
principle measurement is the measured value of CO
2
concentration depends on the value of air
pressure - altitude at the installation site. For this reason, it is suitable for accurate measurement to
set the altitude of the installation site by TSensor software.
After power up there is internal check in progress and takes about 20 s. During this time LCD
display shows (----) instead of CO
2
concentration value.
Parameter setting description is into chapter “
at page 12.
5.4. Actual regulator preset
It is possible to display actual regulator preset on its LCD display by
pressing of „
▲
“ key. If far controlling of output relays status is active (see
at page 19), then device’s LCD display shows text „bloc“. It
means, device’s keyboard is disabled for time of remote control (setting
change), see chapter
at page 20. LCD shows information about Relay1
and then Relay2 setting step by step. Information about Relay1 are indicated
with symbol „
“, for Relay2 with symbol „
“ (at right top corner of LCD). It
is possible to edit parameters after pressing „
SET
“ key and entering of correct password „
PASS
“ –
see chapter “
Change of “Password for setting through keys” (PASS)”
at page 14. Following examples
are for Relay1 setting, similarly are displayed values for Relay2. Pressing of „
ESC
“ key ends this
mode and switch to actual value displaying, the same occur if more than 20 s is not pressed any key.
5.4.1. Value assigned to output relay
None, relay is still off
Temperature at °C
Relative humidity
Computed value – dew point temperature
CO
2
concentration
Far condition 0
