User Manual

HOBO U12 Temp/RH/2 External Data Logger
3
following diagram. The striped bar shows the 16 ms period
during which the logger samples the input signals.
When using multiple voltage and/or current inputs, the (-)
from your current source(s) and the 0 Volt line of your voltage
source(s) are tied together at the logger. If these lines are at
different voltage potentials, this may cause inaccurate readings
or even damage your logger. Keep in mind that these lines
may also be tied to earth ground through your PC interface
cable when connected to your computer. Special precautions
may be necessary if any of your voltage or current source
common lines are not tied to earth ground.
CAUTION: Analog channel input cannot exceed 2.5
VDC. For sensor outputs up to 10 VDC, use
appropriate voltage adapter cable.
Using the RH Sensor
In order to take humidity measurements, the temperature
sensor must be used in conjunction with the RH sensor.
Conditions outside the recommended range may offset the RH
signal. Vapors may also affect the RH sensor. The diffusion of
chemicals into the sensor may cause a shift in both offset and
sensitivity. High levels of pollutants may cause permanent
damage to the sensor.
Upon returning to normal conditions, the RH sensor will
slowly return towards calibration state by itself. However,
prolonged exposure to extreme conditions may accelerate
aging and eventually lead to a permanent shift. To recondition
the sensor, do the following:
1. Remove the battery
2. Warm 24 hours 80–90°C (176–194°F) at < 5% RH
3. Re-hydrate 48 hours 20–30°C (70–90°F) at 75–95% RH
Mounting
There are four ways to mount the logger using the materials in
the mounting kit included with the logger:
• Use the hook and loop tape to affix the logger to a surface.
• Attach the magnet, then place the
logger on a magnetic surface.
• Use the tie wrap and tie wrap mount
to tie the logger to an object.
• Fasten the logger to a surface with
the two Phillips-head screws. The
back of the logger has two inserts for
the screws, 32 mm (1¼ inches) apart.
Battery
The logger requires one 3-Volt CR-2032 lithium battery.
Expected battery life varies based on the temperature and the
frequency at which the logger is recording data (the logging
interval). A new battery will typically last one year with
logging intervals greater than one minute. Deployments in
extremely cold or hot temperatures or logging intervals faster
than one minute may significantly reduce battery life.
To replace the battery:
1. Disconnect the logger from the computer.
2. Unscrew the logger case.
3. Lift the circuit board and carefully push the battery out
with a small blunt instrument, or pull it out with your
fingernail.
4. Insert a new battery, positive side facing up.
5. Carefully realign the logger case and re-fasten the screws.
WARNING: Do not cut open, incinerate, heat above
85°C (185°F), or recharge the lithium battery. The
battery may explode if the logger is exposed to extreme
heat or conditions that could damage or destroy the
battery case. Do not dispose of the logger or battery in
fire. Do not expose the contents of the battery to water.
Dispose of the battery according to local regulations for
lithium batteries.
32 mm
(1¼ inch)