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ESERA GmbH, ESERA-Automation 2020
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11132 V2.0 R1.0 Manual
Page 2 of 5
The 1-Wire Multisensor is integrated into a 1-Wire network using screwless pressure clamps.
The 1-Wire multi-sensor has a 1-Wire interface of type DS2438. Each 1-Wire multi-sensor has an individual serial
number.
This 1-Wire Multisensor has an integrated measuring function for temperature, humidity, brightness and
operating voltage.
3
Why measure humidity?
Room air always contains moisture in the form of water vapour. The relative humidity is decisive for a pleasant
living climate. During the heating period, 35 to 45 % relative humidity can be regarded as optimal. Values above
45 to 55% may already lead to the formation of mould in a poor building envelope. For health reasons, values
below 20 % should be avoided if possible.
The absolute humidity indicates how many grams of water vapour are dissolved in one cubic meter of air.
The warmer the air, the more water it can absorb. The relative humidity says, with how much percent the room-air
is enriched with humidity.One speaks of air completely saturated with humidity when the relative humidity is
100 %. Beyond that the air cannot take up any further humidity. If even more moisture is added, the water vapour
condenses and droplets form. In nature this phenomenon leads to fog formation, in heated rooms the water
vapour from the room air precipitates on cold surfaces. There is a risk of mold growth here.
4
Software / Control
The 1-Wire Multisensor is read by 1-Wire command for DS2438 devices and is supported by many computer
programs like Loxone SPS, WAGO SPS (via OWOS), OWFS, FHEM (Linux), IP-Symcon or microcontroller
applications.
5
Technical data
1-Wire interface: DS2438, Multisensor for temperature, humidity, brightness and operating voltage
Measuring range temp.: -55°C to +60°C (sensor element: -55°C to +125°C)
Accuracy temperature: +/- 0,5° in the range of -10°C - 85°C
Resolution: 9 Bit, 0.03125°C/Bit
Humidity sensor: Capacitive sensor Honeywell
Measuring range humidity: 0-100% rel. humidity
Humidity accuracy: +/-3.5 % (10-85% RH), +/-7% (<10% and >85% RH)
Brightness sensor: Sensor adapted to the sensitivity of the human eye
Measuring range: 2 - 7000 Lux
Accuracy Lux: +/-20% in the range up to approx. 200 Lux, +/-15% in the range up to 7000 Lux
Operating voltage: 5 V= (+/-10%)
Power consumption: approx. 2 mA
Connection: push-in terminal (screwless terminal)
6
Environmental conditions
Protection system: IP00
Protection class: III
Temperature operation of complete sensor: operation -25°C to 60°C
Humidity: 10 - 90% (non-condensing)
Dimensions (outside): 71 x 71 x 32mm (LxWxH)
7
Conformity
EN 50090-2-2, EN 61000-4-2 ESD, EN 61000-4-3 HF, EN 61000-4-4 Burst, EN 61000-4-5 Surge, EN 61000-6-1
Immunity, EN 61000-6-3 Interference, RoHS
8
Calculation
The following formula can be used to evaluate the humidity sensor.
VDD = operating voltage (5V), VAD = analog input DS2438, Xsense = brightness DS2438.
Humidity calculation (simplified formula)
Offset = 0.847847 (Zero Offset V), slope = 29.404604 (Slope: mV/%RH)
Srh = (VAD_neu - offset) / (slope / 1000)
rFH = (Srh + 2)/ ((1.0305 + (0.000044 * temperature) - (0.0000011 * temperature x 10²)))))))
For Loxone control:
I1 = VAD value, I3 = temperature
(((((5/I2*I1)-0.847847)/(29.404604/1000))+2)/((1.0305+(0.000044*I3)-(0.0000011*I3^2))))
