HOBO
®
U12 Temp/RH/Light/
External Data Logger
(Part # U12-012)
© 2003, 2004 Onset Computer Corporation
Part #: MAN-U12-012, Doc #: 7661-B
Inside this package:
•
HOBO U12 Temp/RH/
Light/External Data Logger
•
Mounting kit with magnet, hook
and loop tape, tie-wrap mount,
tie wrap, and two screws.
Doc # 7661-B, MAN-U12-012
Onset Computer Corporation
Thank you for purchasing a HOBO data logger. With proper care, it
will give you years of accurate and reliable measurements.
The HOBO U12 Temperature/Relative Humidity/Light/External Data
Logger is a four-channel logger with 12-bit resolution and can record
up to 43,000 measurements or events. The external channel accepts a
variety of sensors, including temperature, and split-core AC current
sensors as well as 4-20 mA and voltage input cables (sold separately).
The logger uses a direct USB interface for launching and data readout
by a computer.
An Onset software starter kit is required for logger operation. Visit
www.onsetcomp.com for compatible software.
Specifications
Measurement
range
Temperature: -20° to 70°C (-4° to 158°F)
RH: 5% to 95% RH
Light intensity: 1 to 3000 footcandles (lumens/ft
2
) typical;
maximum value varies from 1500 to 4500 footcandles
(lumens/ft
2
)
External input channel (see sensor manual): 0 to 2.5 DC Volts
Accuracy
Temperature: ± 0.35°C from 0° to 50°C (± 0.63°F from 32° to
122°F), see Plot A
RH: ± 2.5% from 10 to 90%, see Plot B; conditions above
80% RH and 60°C (140°F) may cause additional error
Light intensity: Designed for indoor measurement of relative
light levels, see Plot D for light wavelength response
External input channel (see sensor manual): ± 2 mV ± 2.5% of
absolute reading
Resolution
Temperature: 0.03°C at 25°C (0.05°F at 77°F), see Plot A
RH: 0.03% RH
Drift
Temperature: 0.1°C/year (0.2°F/year)
RH: <1% per year typical; RH hysteresis 1%
Response time
in airflow of 1
m/s (2.2 mph)
Temperature: 6 minutes, typical to 90%
RH: 1 minute, typical to 90%
Time accuracy
± 1 minute per month at 25°C (77°F), see Plot C
Operating
temperature
Logging: -20° to 70°C (-4° to 158°F)
Launch/readout: 0° to 50°C (32° to 122°F), per USB
specification
Battery life
1 year typical use
Memory
64K bytes (43,000 12-bit measurements)
Weight
46 g (1.6 oz)
Dimensions
58 x 74 x 22 mm (2.3 x 2.9 x 0.9 inches)
The CE Marking identifies this product as complying with all
relevant directives in the European Union (EU).
Plot A
Plot B
Plot C
Plot D
Connecting the logger
The U-Family logger requires an Onset-supplied USB interface cable to
connect to the computer. If possible, avoid connecting at temperatures
below 0°C (32°F)
or above 50°C (122°F).
1. Plug the large end of the USB interface cable into a USB port on the
computer.
2. Plug the small end of the USB interface cable into the bottom of the
logger as shown in the following diagram.
If the logger has never been connected to the computer before, it may take
a few seconds for the new hardware to be detected. Use the logger
software to launch and read out the logger.
Important: If you configure the logger to start with a button start, be
sure to press and hold down the button on the front of the logger for
at least three seconds when you want to begin logging.
If using an external sensor, be sure to plug it into the side of the logger
before logging begins. Also select the correct sensor and activate the
external channel in the logger software when configuring the launch.
Important: If you select an external channel, but do not plug the
probe in, false data will be recorded for that channel.
You can read out the logger while it continues to log, stop it manually
with the software, or let it record data until the memory is full.
Refer to the software user’s guide for complete details on launching,
reading out, and viewing data from the logger.
Sample and event logging
The logger can record two types of data: samples and events. Samples are
the sensor measurements recorded at each logging interval (for example,
the temperature every minute). Events are independent occurrences
triggered by a logger activity. Examples of events recorded
asynchronously during deployment include when the logger is connected
to the host, when the battery is low, the end of a data file once the logger
is stopped, and button pushes.
Press the button on the front of the logger for one second to record an
event. Both a button up and down event will be recorded. This is useful if
you want to mark the datafile at a particular point. For example, if the
logger is located in an incubator, you might press the button each time the
door is opened.
The logger stores 64K of data, and can record up to 43,000 samples and
events combined.
Using external sensors
The external input channel has a switched 2.5 V output. This signal can be
used to power a sensor directly or it can also be used to trigger an external
circuit. An external sensor should draw no more than 4 mA total when
powered. The switched 2.5 V output turns on about 15 ms before the
external channel is measured and stays powered for 48 ms after it is
measured, as shown in the following diagram. The striped bar shows the
16 ms period during which the logger samples the input signal.
15 ms
16 ms
48 ms
Important:
Press this
button for
3 seconds
when logger is
launched with Button
Start or press for
1
second
to record an
event while logging
USB interface
cable plugged
into logger
Light
intensity
sensor
