7. D6 temperature / humidity sensor FHAD46C
D6 temperature / humidity sensors FHAD46C are based on the fully adjusted Multi-
sensor module FH0D46-Cx; this comprises a capacitive temperature / humidity sensor,
a barometric atmospheric pressure sensor, and an EEPROM. (see Figure 7-1) This
means that the Multi-sensor module can be replaced or adjusted quickly and easily
without any loss in accuracy. The Multi-sensor module incorporates a unique serial
number designed to exclude any risk of incorrect replacement; this serial number can
be displayed via the sensor menu. (see Figure 7-1) The barometric atmospheric pres-
sure sensor is used to determine atmospheric pressure directly at the measuring loca-
tion. On this basis atmospheric pressure compensation can then be performed
automatically in the ALMEMO
®
connector. Information stored in the integrated EEP-
ROM ensures that the Multi-sensor module can be adjusted quickly and easily. The
humidity variables are calculated from the real measurable variables - temperature,
relative humidity, atmospheric pressure - on the basis of formulae as per Dr. Sonntag
and the enhancement factor as per W. Bögel (correction factor 'fw(t,p)' for real mixed
gas systems). The measuring range and accuracy of this system are thus much greater
than with earlier sensors. The measured atmospheric pressure can also be used in the
ALMEMO
®
measuring instrument as reference atmospheric pressure (see 3.2).
Figure 7-1 Multi-sensor module FH0D46-C
7.1 Measuring quantities and ranges - factory default settings
Description
Range
Exp. Measuring
range
Units Resolution
1. Temperature T, t
B-01
DIGI
-2
-20..+80.00
+
°C
0.01 K
2. Rel. humidity RH, U
w
B-02
DIGI
-1
5... 98.0 %H
0.1 % rH
3. Dewpoint DT, t
d
B-03
DIGI
-1
°C
0.1 K
4. Atm. pressure AP, p
B-08
DIGI
-1
300...1100.0 mb
0.1 mb
+
The measuring range depends on the sensor type. (see data sheet)
Providing the appropriate ALMEMO
®
standard quantities 'H DT', 'H AH', 'H VP', 'H En'
have been programmed accordingly, the D6 humidity ranges can be configured partly on
the device itself. 'DIGI' will substitute these ranges automatically with the new ones.
(see 7.2.1).
Please note that in this process new ranges 'D dv' or 'D p' may be lost.
They can then only be restored via the PC.
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