HOBO® U12 4-External Channel
Outdoor/Industrial Data Logger
(Part # U12-008)
Inside this package:
• HOBO U12 4-External Channel Outdoor/Industrial Data
Logger
• Desiccant pack
• Mounting/spare parts kit: two socket head screws, dome
plug and O-ring, O-ring lubricant, four mounting screws,
four flat washers, Allen wrench, and four tie wraps.
Thank you for purchasing a HOBO data logger. With proper
care, it will give you years of accurate and reliable
measurements.
The HOBO U12 4-External Channel Outdoor/Industrial data
logger has a 12-bit resolution and can record up to 43,000
measurements or events. The four external channels accept a
wide range of Onset and third-party sensors/transducers with
a 0-2.5 VDC output, including external temperature, AC
current, pressure, air velocity, and kW sensors. Specifications
for Onset sensors can be found at www.onsetcomp.com or by
contacting your Onset Authorized Dealer. For 0-5 VDC, 0-10
VDC, or 4-20mA output, use optional Onset Part No.
CABLE-ADAP5, CABLE-ADAP10, or CABLE-4-20mA
respectively.
The logger uses a direct USB interface for launching and data
readout by a computer.
Onset software is required for logger
operation. Visit www.onsetcomp.com for details.
Specifications
Measurement
range
Accuracy
(logger only)
Resolution 0.6mV
Time accuracy ± 1 minute per month at 25°C (77°F), see Plot A.
Operating range -20 to 70°C (-4° to 158°F)
Operating
temperature
Battery life 1 year typical use (see The Battery on page 4 for details)
Memory 64K bytes (43,000 12-bit measurements)
Weight 200 g (7 oz)
Dimensions 140 x 137 x 32 mm (5.5 x 5.38 x 1.25 inches)
External input channels (see sensor manual): 0 to 2.5 VDC
(with CABLE-ADAP5) and 0 to 10 VDC (with
CABLE-ADAP10)
± 2 mV ± 2.5% of absolute reading
± 2 mV ± 1% of reading for logger-powered sensors
Weatherproof case tested to NEMA 6 standard
Logging: -20° to 70°C (-4° to 158°F)
Launch/readout: 0° to 50°C (32° to 122°F), per USB
specification.
The CE Marking identifies this product as complying with
all relevant directives in the European Union (EU).
Plot A
Accessories
• Replacement Parts Kit (Part # H8X4-BK)
• Replacement Desiccant (Part # DESICPACK)
• U-Bolt (Part # U-BOLT-KIT)
© 2011 Onset Computer Corporation. Onset and HOBO are registered trademarks of Onset Computer Corporation. Other products and brand names
may be trademarks or registered trademarks of their respective owners.
Part #: MAN-U12008, Doc #: 13132-D
HOBO® U12 4-External Channel Outdoor/Industrial Data Logger
4-20mA Input Cable
This cable (part number CABLE-4-20mA) measures current
from 0 to 20.1 mA. Do not expose to current above 20 mA or to
negative current. Do not cut off the end of the gray cable where
it connects to the blue and yellow wires, as it contains the
precision resistor required for current measurement.
If you are using this cable outdoors, you will need to ensure that
the connection to your sensor or device is also weatherproof.
The connection between the gray cable and yellow and blue
wires is splash-proof, but not weatherproof.
Voltage Input Cable
The logger’s external inputs can accept the voltage input cable
(Onset part number CABLE-2.5-STEREO), which allows a
voltage to be recorded. The input line must not be exposed to
signals below 0 V or above 2.5 V.
If you are using this cable outdoors, you will need to ensure that
the connection to your sensor or device is also weatherproof.
Voltage Input Cable Connections
Wire Connection
Red Switched 2.5 V output
White Voltage input
Black Ground
Other External Sensors
Onset has a range of external temperature sensors, AC current
sensors, and cables for incorporating other sensors that are
compatible with the U12 4-External Channel Data Logger.
Measurement specifications for using Onset temperature and AC
current sensors with this logger are provided in the sensor
manuals. Visit www.onsetcomp.com for details on compatible
sensors.
computer. Special precautions may be necessary if any of your
voltage or current source common lines are not tied to earth
ground. Input isolators may be needed in industrial environments
to prevent errors caused by ground loops.
CAUTION: Analog channel input cannot exceed 2.5
VDC. For sensor outputs up to 10 VDC, use appropriate
voltage adapter cable.
Attaching the Sensors
1. Remove the socket head screws in the corners of the cover
and lift the cover from the device. Save the screws to
reattach the cover later.
2. Using a 15 mm wrench, remove the dome nut for the
channel you wish to connect to.
3. Pull the exposed end of the black rubber plug to remove it
from the fitting. Do not throw these plugs away! These
plugs are needed to maintain a weatherproof seal for
channels that are not connected to sensors or input cables.
4. Slide the dome nut over the plug end of the cable. The dome
nut’s threads should face towards the case.
5. Feed the plug end of the cable from the outside of the case
through the dome fitting of the channel you want to use
(refer to label on the logger’s cover) and plug it into the
corresponding port as shown in the diagram. The sensor
cable must be inserted through the fitting to ensure
proper logger operation. If you have difficulty inserting
the plug through the fitting, a small amount of dishwashing
liquid can be used as a lubricant on the plug. (Do not use Oring lubricant.)
Switched 2.5 V Output
The external input channels have a switched 2.5 V output. This
signal can be used to power a sensor directly, or it can be used to
trigger an external circuit. External sensors should draw no more
than 4 mA total when powered.
The switched 2.5 V output turns on about 1 ms before the
external channels are measured
and stays powered for 21 ms
after the external channels are
measured, as shown in the
diagram. The grey area 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 V 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
6. Thread the dome nut back onto fitting and hand-tighten it.
Tighten an additional half-turn with a 15 mm wrench.
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HOBO® U12 4-External Channel Outdoor/Industrial Data Logger
7. Make sure the desiccant cartridges are fresh. (If you are
using the logger for the first time, remove the two desiccant
cartridges from the foil pouch and install them in the cavity
at the top of the case.) Cartridges are blue when new, and
fade to pale pink when they need to be replaced. If they are
pale pink, discard them and replace them with two new
(blue) ones (part # DESIC-PACK).
8. Close the logger’s case as described in the “Closing the
logger” section of this manual.
Replacing Desiccant Cartridges
Periodically check the desiccant cartridges by looking through
the viewing window on the logger’s case. The cartridges are blue
when new, and fade to pale pink when they need to be replaced.
Discard the old cartridges and replace them with two new blue
ones (part # DESIC-PACK).
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. Using a screwdriver, small coin, or similar object, turn the
dome plug counter-clockwise and set it aside.
2. Plug the large end of the USB interface cable into a USB port
on the computer.
3. Plug the small end of the USB interface cable into the logger
as shown in the diagram. (You may find it easier to see the
port if the logger’s cover is off.)
Launching the Logger
Be sure to plug the external sensors into the logger before
launching. Also select the correct sensors and activate the
external channels 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.
If you configured the logger to start with a button start, press and
hold down the button on the front of the logger for at least three
seconds when you want to begin logging data. Then close the
logger’s cover.
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.
Protecting the Logger
Static electricity may cause the logger to stop logging. To
avoid electrostatic discharge, transport the logger in an antistatic bag, and ground yourself by touching an unpainted metal
surface before handling the logger. For more information about
electrostatic discharge, visit our website at
http://www.onsetcomp.com/Support/support.html.
Closing the Logger
Follow these steps to ensure a secure, weatherproof seal.
1. Make sure the dome plug is in place.
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.
After you disconnect the logger from the computer, remember to
put back the dome plug. Make sure that the dome plug O-ring is
still in place. Then, turn the dome plug clockwise until the Oring is snug.
2. Lubricate and install the large O-ring around the face of the
logger. It should be clean, lubricated, and fully seated into the
groove. (Additional O-ring lubricant is available from Onset
Computer; part # 85-SILICONE-1.)
3. Place the cover on the case. The clear area on the label
should be positioned over the desiccant cavity.
4. Attach the cover loosely using the two socket head screws set
aside in Step 1 of Attaching the Sensors and the two identical
screws in the mounting/spare parts kit. Make sure the O-ring
is still seated properly.
5. Starting at any corner, tighten a socket head screw, then
tighten the screw in the opposite corner. Tighten the two
remaining screws and inspect O-ring through the clear cover
to ensure proper sealing all around. Make sure all four
screws are in place.
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 (if applicable).
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HOBO® U12 4-External Channel Outdoor/Industrial Data Logger
Since you must remove the logger’s cover to access the button,
button pushes should be done only if the logger is adequately
protected from moisture and other environmental factors that
could damage it. To mark an event, press the button for at least
one second. Both a button up and a button down event will be
recorded.
The logger stores 64K of data, and can record up to 43,000
samples and events combined.
Operation
A light (LED) on the front of the logger confirms logger
operation. The following table explains when the logger blinks
during logger operation:
When: The light:
The logger is logging Blinks once every one to four
seconds (the shorter the logging
interval, the faster the light blinks);
blinks when logging a sample
The logger is awaiting a
start because it was
launched in Start At
Interval, Delayed Start,
or Button Start mode
The button on the logger
is being pushed for a
Button Start launch
Blinks once every eight seconds
until launch begins
Blinks once every second while
pressing the button and then
flashes rapidly once you release
the button. The light then reverts
to a blinking pattern based on the
logging interval
Mounting
Four mounting screws and washers are included with your
logger. Use these screws to mount the logger to a wooden post.
UV-stable tie wraps also work well.
U-bolt clamps (part # U-BOLT-KIT) are preferred for mounting
to a 1" pipe (1.3" outside diameter), as shown.
The 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. Onset recommends
that you install a fresh battery before every deployment if
temperatures below 0°C (32°F) are expected.
To replace the battery:
1. Disconnect the logger from the computer.
2. Use the Allen wrench to remove the four socket head screws
on the logger’s cover. Then remove the cover.
3. Carefully insert a thin screwdriver blade between the edge of
the battery and the battery contact that is farther from the red
LED. Gently pry up the edge of the battery, popping it out of
the holder.
4. Slide the new battery, positive side up, under the two small
tabs of the contact that is closer to the red LED. Press down
on the battery until it snaps into place. The logger’s LED will
blink several times.
5. When the new battery is secure, close the logger’s case as
described in the “Closing the logger” section of this manual.
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
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