Hobo Micro Station User manual

7645-L
HOBO®Micro Station User’s Guide

ii HOBO Micro Station User’s Manual
Contact Information
For support, please contact the company that you bought the product from: Onset Computer Corporation or an Onset
Authorized Dealer.
Onset Computer Corporation
470 MacArthur Blvd.
Bourne, MA 02532
Mailing Address:
P.O. Box 3450
Pocasset, MA 02559-3450
Phone: 1-800-LOGGERS (1-800-564-4377) or 508-759-9500
Fax: [phone]
Customer Service Hours: 8AM to 5PM Eastern Time
Technical Support Hours: 8AM to 8PM Eastern Time
E-mail: [e-mail]
Main Onset Web site: www.onsetcomp.com
WARNING: Fire, Explosion, and Severe Burn Hazard. Do not mix battery types, either by
chemistry or age; batteries may rupture or explode. When replacing the batteries, read and follow
their disposal instructions; dispose of lithium batteries according to local regulations. Do not
dispose of batteries in fire. Never attempt to recharge a lithium or alkaline battery. Do not heat
the batteries above 185°F (85°C). Do not mutilate or rupture the battery housing. Lithium
batteries may explode if the logger is exposed to extreme heat or conditions that could damage or
destroy the battery case. Do not expose the contents of the battery to water.
WARNING: Severe shock hazard. Before installing tripod or mounting poles, ensure that there
are no electrical power lines overhead. Do not install the system during any atmospheric
electrical activity. Do not assemble or transport tripods, mounting poles, or other structures
unless there is sufficient clearance from potential electrical sources or other obstructions.
WARNING: Do not climb on or around the tripod (if using). The Micro Station and any of its
associated hardware, towers, poles, etc. are not designed to support the weight of a person. Injury
may result.
WARNING: If using stakes to stabilize the tower, ensure that there are no underground wires or
pipes under the Micro Station.
WARNING: Do not use weather station as part of a critical control system. This system is not
intended to be a fail-safe mechanism for anticipating life-threatening conditions, such as flash
floods.
©2003–2014 Onset Computer Corporation, all rights reserved.
Printed in the USA.
Onset, HOBO, and HOBOware are registered trademarks of Onset Computer Corporation. Gore Vent is a trademark
of W. L. Gore and Associates. All other trademarks are the property of their respective companies.

HOBO Micro Station User’s Guide iii
Table of Contents
Chapter 1 Introduction................................................................................................................................1
Specifications...................................................................................................................................1
How to use this manual....................................................................................................................2
Smart sensors supported.................................................................................................................2
Chapter 2 Assembly and testing ...............................................................................................................3
Items required..................................................................................................................................3
Logger and smart sensor setup instructions....................................................................................3
Testing the logger ............................................................................................................................6
Configuring HOBOware for a Keyspan®USB-to-Serial Adapter .....................................................7
Chapter 3 Logger operation.......................................................................................................................8
Logger components .........................................................................................................................8
Status lights.......................................................................................................................................9
Communicating with the logger........................................................................................................9
Launching........................................................................................................................................10
Selecting and installing batteries ...................................................................................................11
Estimating battery life......................................................................................................................12
Checking battery status...................................................................................................................13
Adding and removing sensors .......................................................................................................13
Time accuracy................................................................................................................................14
Logger memory..............................................................................................................................15
Chapter 4 Field setup and mounting.......................................................................................................17
Guidelines for typical field setup ....................................................................................................17
Guidelines for a tripod system setup ...............................................................................................18
Guidelines for installing sensors......................................................................................................18
Mounting instructions for a flat surface..........................................................................................19
Using Micro Station accessories....................................................................................................20
Mounting the logger with the Mast Mounting Kit..............................................................................20
Connecting the External Grounding Wire Adapter Cable ................................................................21
Connecting the External Communications Port Adapter Cable .......................................................22
Field preparation checklist .............................................................................................................23
Set up the tripod, cross arm, and sensors.....................................................................................26
Chapter 5 Troubleshooting......................................................................................................................28
Chapter 6 Maintenance.............................................................................................................................30
Maintenance...................................................................................................................................30
Performing a visual inspection.........................................................................................................30
Cleaning the Micro Station ..............................................................................................................30
Checking the desiccant pack...........................................................................................................31
Replacing the batteries....................................................................................................................31
Verifying the sensor accuracy..........................................................................................................31

Chapter 1: Introduction
HOBO Micro Station User’s Guide 1
Chapter 1
Introduction
The HOBO®Micro Station is a four-sensor data logger designed for
applications requiring multi-channel monitoring of microclimates in
one or more locations. Part of the HOBO Weather Station family, the
Micro Station uses a network of smart sensors for taking
measurements. Key features of the smart sensors include:
•Automatic detection upon launch. No extensive
programming, wiring, or calibrating is required to set up
sensors.
•Easy expansion. Because the logger is not pre-configured, up
to four sensors of any type or combination can be added
simply by plugging them in before logging begins. Using an
expansion chassis, up to 15 data channels are possible.
•Digital network. The connections between the smart sensors
and the logger are digital, ensuring accurate, reliable data collection and storage.
•Weatherproof. A silicone gasket around the edge of the case keeps out moisture, while a Gore™
Vent allows the case to breathe while also keeping moisture out.
Specifications
HOBO Micro Station
Operating Range -20° to 50°C (-4° to 122°F) with alkaline batteries,
-40° to 70°C (-40° to 158°F) with lithium batteries
Sensor Inputs Up to four smart sensors (including multiple-parameter sensors)
Communication 3.5 mm serial port or use serial-to-USB adapter cable (ADAP-SER-USB)
to connect to a USB port on the computer
Dimensions 8.9 cm H x 11.4 cm D x 5.4 cm W (3.5 x 4.5 x 2.125 inches)
Weight 0.36 kg (0.8 lb)
Memory 512K nonvolatile flash data storage
Memory Modes Stop when full, wrap around when full
Operational Indicators Seven lights provide logging and sensor network status
Logging Interval 1 second to 18 hours, user-specified interval
Battery Life 1 year typical use (up to 4 sensors with 1 minute or longer logging
interval)
Battery Type Four standard AA alkaline batteries included (for operating conditions -20°
to 50°C [-4° to 122°F]); optional AA lithium batteries available for
operating conditions of -40° to 70°C (-40° to 158°F)
Time Accuracy 0 to 2 seconds for the first data point and ±5 seconds per week at 25°C
(77°F)
Data Type Supports measurement averaging for select sensors
Logger Start Modes Immediate, push-button, or delayed start options
Data Communication Current reading while logging, offload while logging, or offload when
stopped
Environmental Rating Weatherproof, with GoreTM Vent and silicone gasket for deployment in
harsh weather conditions, tested to NEMA 4x and IP66

Chapter 1: Introduction
2 HOBO Micro Station User’s Manual
HOBO Micro Station
Mounting Mount vertically on flat surface 18 cm (3.5 inches) or wider; optional mast
mounting kit for use on 4.1 cm (1 5/8 inches) diameter masts
Enclosure Access Cover secured by four screws
Sensor Network Cable
Length 100 m (328 ft) maximum
Part Number H21-002
The CE Marking identifies this product as complying with all relevant
directives in the European Union (EU).
How to use this manual
This manual covers the steps to set up, operate, and maintain the Micro Station, including:
•Assembling the logger and perform an initial test
•Operating the logger
•Setting up the Micro Station in the field
•Troubleshooting problems
•Maintaining the Micro Station and getting service and support
It is important that you test your system using the steps in Chapter 2 before continuing with other chapters
in the manual and installing the Micro Station on site.
Smart sensors supported
The Micro Station supports a range of smart sensors, including:
•Temperature
•Temperature/relative humidity
•Rain
•Soil moisture
•Wind speed
•Wind direction
•Barometric pressure (part # S-BPB-CM50 only)
•Solar radiation
•Photosynthetic active radiation (PAR)
•0-5 Volt Input Adapter
•4-20 mA Input Adapter
•Pulse Input Adapter (contact closure and electronic switch)
Refer to www.onsetcomp.com for a current list of compatible sensors.
Refer to the manuals provided with the sensors for sensor specifications, mounting information, and
recommended maintenance.

Chapter 2: Assembly and testing
HOBO Micro Station User’s Guide 3
Chapter 2
Assembly and testing
The HOBO Micro Station is shipped partially assembled. This section explains how to assemble the
logger, connect the smart sensors, and perform a quick test.
Items required
To configure the Micro Station you will need the following:
•One to four smart sensors
•Phillips-head screwdriver
•Slotted screwdriver or small coin
•Pen, pencil, or other blunt instrument
•Adjustable 8 inch or 10 inch crescent wrench
•Utility or pocket knife
•PC interface cable (CABLE-PC-3.5) for serial ports; USB serial adapter (ADAP-SER-USB) if no
serial port is available
•Computer with logger software installed
•Silicone grease tube
Logger and smart sensor setup instructions
1. Insert four AA alkaline or lithium batteries. For more details on which type of batteries to use, see
the Selecting and installing batteries section in Chapter 3 on page 11.
2. Place the battery strap on the batteries.
Battery strap

Chapter 2: Assembly and testing
4 HOBO Micro Station User’s Manual
3. With a crescent wrench, remove the dome nut from the stuffing gland in the sensor port.
4. Push the slit insert out from the inside of case. You may need to push the slit insert out using a
pen (capped end), pencil (eraser end), or other blunt instrument.
5. Some sensors have an anti-snag device on the connector as shown below. If any of your sensors
has this device, check that the connector fits through the stuffing gland.
If the connector does not fit through the stuffing gland, you will need to trim the anti-snag device
with a knife so that the connector looks like the one below.
Anti-snag device on
some external sensor
connectors
Anti-snag device
removed from the
external sensor
connector
Dome nut
Stuffing gland on sensor port
Stuffing gland slit insert

Chapter 2: Assembly and testing
HOBO Micro Station User’s Guide 5
6. Insert the sensor connectors through the dome nut. The threaded side of the dome nut should be
facing towards the connector. Then, slide the cables through the stuffing gland and through the
hole in the case. Push the cables into the slit insert.
Note: The electronics on some older temperature sensors are housed in a tube that is close to the
sensor connector. If you have any of these sensors, be sure to insert them first because they will
need more room inside the logger. Adjust the sensor as needed so that the tube with the
electronics fits inside the logger without too much unnecessary bending of the cable.
7. Plug the sensors into the logger. Adjust the cable length as necessary so there isn’t excess cable
inside the case.
8. If you are using fewer than four sensors, add the o-ring cord(s) to plug the empty hole(s) in the
slit insert.
9. Apply some silicone grease to the slits on the insert.
10. Push the slit insert back into the stuffing gland. Pushing the slit insert in at a slight angle and with
a slight twist may help it slide in more smoothly.
11. Screw the dome nut onto the stuffing gland, tighten by hand, and then an additional ½ to ¾ turn
with an adjustable wrench. The dome nut must be snug, but shouldn’t be overtightened.
12. From the back side of the stuffing gland, fill the void inside with silicone grease from the
package.
13. Remove the desiccant pack from its foil pouch and place inside the logger enclosure to minimize
internal condensation.
14. Apply silicone grease to the outside rim of the case where the cover meets up with the housing.
The grease should be applied sparingly in this location.
15. Screw the clear cover back onto the case. Use a Phillips-head screwdriver to tighten the four
cover screws.
Dome nut
Slit insert
Sensor cable and
connector
Stuffing gland on sensor port
O-ring cord to fill empty holes

Chapter 2: Assembly and testing
6 HOBO Micro Station User’s Manual
Testing the logger
It is recommended that you test the logger before setting it up in the field. To test the logger:
1. Use a slotted screwdriver or small coin to unscrew the data access port cover.
2. Insert the PC interface cable through the data access port and plug it into the communications port
on the logger. If the computer does not have a serial port, refer to the next section on using the
Keyspan USB-to-Serial Adapter.
3. Using the logger software, select the Launch icon.
4. Make sure all the sensors you plugged in are visible in the Launch screen.
5. Choose a logging interval of a few seconds so that your test will yield enough data to look at.
Select the Start Logging Now option, and click the Start button to launch the logger.
6. After a couple of minutes, read out the logger. You can choose to either stop the logger and read
it out or let it continue logging while reading out.
7. Check the data and make sure it appears normal for all sensors.
For more details on launching and logger operation, see Chapter 3. For information on mounting the
logger and setting it up in the field, see Chapter 4.
Data access port
cover
PC interface cable
plugged into
communications port

Chapter 2: Assembly and testing
HOBO Micro Station User’s Guide 7
Configuring HOBOware for a Keyspan
®
USB-to-Serial Adapter
If the computer does not have a serial port, you will need to use a Keyspan adapter (ADAP-SER-USB).
1. Install the Keyspan USB-to-serial adapter software from the CD included with the device or
download the software from the Support tab at:
http://www.tripplite.com/en/products/model.cfm?txtModelID=3914
Follow the Keyspan installation instructions.
2. Open the Keyspan USB Serial Adapter Assistant and the note the COM number assigned to the
device. In this example, it is COM4.
3. Open HOBOware. From the File menu on Windows or from the HOBOware menu on Mac, select
Preferences. Under Communications, click the arrow to open Device Types. Make sure “USB and
serial devices” is selected. Click the arrow to open Serial Ports. Select the COM port noted in
Step 2 (in this example, it is COM4). Note: On a Mac, the Keyspan adapter will be listed as
something similar to “USA19H1d1P1.1.”
Click OK in the Preferences window to save these settings. HOBOware should now be configured to
work with the Keyspan USB-to-serial adapter.

Chapter 3: Logger operation
8 HOBO Micro Station User’s Manual
Chapter 3
Logger operation
This chapter explains key elements of Micro Station operation, including:
•Definition of logger components
•How to communicate with the logger, including launching and reading out
•Guidelines for selecting and installing batteries
•Time accuracy of the logger
•Logger memory
Logger components
The following diagram explains the key parts of the Micro Station.
Status lights, see table
in this section for
details on each of the
seven lights
Sensor port
Data access port
Communications port;
used for connecting to a
computer
Start logging button; use
this button when logger is
configured to launch with a
push button start. Press and
hold until all lights flash
Battery holder, with
batteries installed and
battery strap in place Sensor connection
ports, where up to
four sensors can be
plugged in
External connection
access port
Connector for grounding wire
and remote communications
(optional)
Gore™Vent, along
with silicone gasket,
allows case to breathe
without allowing in
moisture

Chapter 3: Logger operation
HOBO Micro Station User’s Guide 9
Status lights
There are seven lights on the Micro Station that indicate logger activity and status. The following table
explains the function of these lights.
This light: Blinks when: Notes
Sensor Activity There is activity on the sensor
network. Network activity is defined as communication from the logger to the sensor or vice versa.
Delay Start The logger has been configured to
launch at a specific date/time; will
continue blinking until the defined
start date/time.
The logger will not record measurements while this
light is blinking. Sensors can be added at this time.
Button Start The logger has been configured to
start with a push button start; will
continue blinking until you press and
hold the button on the logger for a
couple of seconds.
The logger will not record measurements while this
light is blinking. Sensors can be added at this time.
OK Every two seconds while the logger is
recording data from sensors. Sensors cannot be added at this time.
Bat Low The battery power is less than 25%
capacity. The logger will continue to run. However, you should read out the logger and then replace the
batteries soon.
Mem Low Less than 25% of memory is
available for saving data. The logger will continue to run until all memory is used. This light will only blink if the logger is
configured to stop logging when memory fills.
Error There is or has been a sensor
communication failure. If this light is blinking in conjunction with the OK light, there was a communication failure. The
system has recovered, but you may have an
intermittent problem.
If this is the only blinking light, then at least one
sensor is currently not communicating. Immediate
investigation is recommended.
In general, it is recommended that you read out
any data when this light is blinking, investigate the
problem, and re-launch the logger.
Communicating with the logger
You can launch, read out, or check the status of the Micro Station with a computer or HOBO U-Shuttle
(U-DT-1).
1. Use a slotted screwdriver or small coin to unscrew the data access port cover.
Data access port
cover

Chapter 3: Logger operation
10 HOBO Micro Station User’s Manual
2. Insert the PC interface cable or shuttle cable through the data access port and plug it into the
communications port on the logger.
Once connected to the computer, use the logger software to configure the launch, read out the logger, or
simply check the status. See the following sections for general information on launching and reading out.
Refer to the HOBOware®user’s guide for detailed information. Refer to the HOBO U-Shuttle manual for
instructions on launching, reading out, or checking status with a HOBO U-Shuttle.
Launching
To launch the logger with HOBOware:
1. Connect the logger to the computer and open HOBOware.
2. Select Launch from the Device menu or click the Launch icon on the toolbar to open the Launch
Logger window.
3. In the Description field, type a description for the launch. This description will be used as the
default file name when you read out and save the data recorded by the logger.
4. In the User Notes field, type up to 2,000 characters of information about the deployment
(optional).
5. Select each sensor you want to include in the deployment. Only the sensors that are currently
plugged in or built into the logger are listed. Sensors are listed in ascending order by serial
number, regardless of their physical position in the logger. If you add or remove sensors, click
the Refresh button to make sure your changes are seen by the logger and displayed in this list.
6. Type in a label for each sensor (optional).
7. Click the Filters button to create any additional filtered series, such as average temperature per
day, automatically when you read out the logger and plot the data.
8. Select a logging interval, which is how often the logger will record data. You can choose either
one of the preset logging intervals or specify a custom logging interval. The minimum logging
interval is one second and the maximum for most loggers is 18 hours, 12 minutes, and 15
seconds. The shorter the logging interval, the more quickly memory fills and battery power is
consumed.
9. Select a sampling interval, if applicable. The sampling interval allows you to take multiple
measurements within the logging interval, then average them together to create a single logged
measurement. The sampling interval is optional and is valid only for sensors that support
Cable plugged into
communications port

Chapter 3: Logger operation
HOBO Micro Station User’s Guide 11
measurement averaging. Refer to the sensor's user manual to determine whether measurement
averaging is available on the sensor. If you have at least one sensor that supports measurement
averaging, click the Enable button, then set the sampling interval at less than or equal to the
logging interval (up to four minutes). Rapid sampling (faster than one minute) will reduce the
logger's battery life. If you do not have any sensors with measurement averaging or wish to turn
off the sampling interval, click the Disable button.
10. Select when to start logging. You can choose to launch the logger:
•Now. Logging begins as soon as you click the Start button. If you do not have at least one
sensor attached, the logger will not launch.
•At Interval. Logging will begin at an exact interval (for example 9:00:00 rather than 8:47:00
when you choose a one-hour logging interval). The exact start time depends on the logging
interval you choose.
•Push Button. Logging will not start until you press the button on the logger and hold it down
for at least three seconds.
•On Date/Time. Logging will begin at a date and time you specify, up to approximately six
months from the present.
•Save Settings in Logger. Logging will not start, but the launch settings will be saved so that
you do not have to re-enter them when you are ready to launch at a later time. The next time
you view the Launch window for this logger, the settings you entered will still be in place.
11. Select when to stop Logging, either “when memory fills” or “never (wrapping).” If you select
“when memory fills,” then the logger will stop recording data once the memory is full. If you
select “never (wrapping),” the logger will record data continuously until either the logger battery
runs out or you stop it. Once the logger is full, the newest data will overwrite the oldest data.
12. Click the Start button when you are finished choosing the launch settings. Note that the text on
the Start button varies depending on when you chose logging to begin. HOBOware displays the
progress of the launch and warns you not to unplug the logger while it is being configured.
Reading out
To read out the logger with HOBOware:
1. Connect the logger to the computer and open HOBOware.
2. Select Readout from the Device menu or click the Readout icon on the toolbar. If the Micro
Station is logging, you can choose to either stop the logger before reading out or to let it continue
logging.
3. After the readout is complete, you can plot the data. Note that readout speed depends on the
method used to connect to the logger and the device being used. Typically, a readout via PC
interface cable with the computer will take about six minutes for a full Micro Station (512K of
data).
Selecting and installing batteries
The Micro Station requires four 1.5 volt AA batteries. The logger is shipped with four alkaline batteries,
but it is also compatible with lithium batteries.
For most applications, alkaline batteries are the preferred solution because:
•They are relatively inexpensive

Chapter 3: Logger operation
12 HOBO Micro Station User’s Manual
•The battery gauge in the logger software will provide an accurate battery status
•They have slightly more usable capacity than 1.5 Volt lithium batteries in temperate
environments
In cold applications (below 0°C [32°F]) and hot applications (above 40°C [104°F]), lithium batteries will
generally outperform alkaline batteries. Alkaline batteries will still work in temperatures ranging from
40° to 50°C (104° to 122°F) and from -20° to 0°C (-4° to 32°F), however, they may not be the best
choice. At temperatures lower than -20°C (-4° F) and higher than 50°C (122°F), alkaline batteries are
unsuitable; use lithium instead. If the temperature is variable across the extremes, use lithium batteries.
Use the following figure to help you choose the battery type based on the expected temperature range in
your deployment.
Recommended battery type based on temperature
Notes:
•The logger is not designed to run with rechargeable or Carbon Zinc “Heavy Duty” batteries.
•Using battery types other than 1.5 Volt alkaline or lithium may result in poor battery performance
and erroneous battery state indication.
WARNING: Fire, Explosion, and Severe Burn Hazard. Do not mix battery types,
either by chemistry or age; batteries may rupture or explode. When replacing the batteries, read
and follow their disposal instructions; dispose of lithium batteries according to local regulations.
Do not dispose of batteries in fire. Never attempt to recharge a lithium or alkaline battery. Do
not heat the batteries above 185°F (85°C). Do not mutilate or rupture the battery housing.
Lithium batteries may explode if the logger is exposed to extreme heat or conditions that could
damage or destroy the battery case. Do not expose the contents of the battery to water.
Estimating battery life
Battery life will vary with:
•Logging and sampling intervals in use (most important factor)
•Number of sensors
•Battery type
•Operating environment
= Recommended in this
temperature range
Lithium
Alkaline
= Works in this temperature
range, but not best choice

Chapter 3: Logger operation
HOBO Micro Station User’s Guide 13
Use the following table to help you estimate how long the batteries will last (the run time) based on the
logging interval. Note: The run times in this table assume that the recommended battery type for the
temperature range is being used and up to four sensors are connected.
Logging interval Sampling Interval Typical battery run time
1 second Off 30 to 50 days
1 minute Off About 12 months
10+ minutes 1 minute 12 months or more
Additional guidelines:
•Turn off the sampling interval unless you have sensors that support measurement averaging,
which includes the 12-bit Temperature, Photosynthetically Active Radiation, and Solar Radiation
smart sensors and the 4-20 mA and 0-5 Volt input adapters. Check the sensor manual to see if
your sensor supports measurement averaging.
•Make sure the “Use Before” date on the battery housing is at least two years from the current
date.
•Alkaline batteries will lose up to 10% of capacity a year sitting on a hot shelf and can lose up to
50% or more if “cooked” repeatedly (for example, stored on a car dashboard). Keeping batteries
in the refrigerator can reduce self-discharge to 1 to 2% per year, however, be sure to avoid
condensation forming on the batteries.
•Use new batteries if you expect the deployment to require a substantial portion of battery life
based on the table above.
•Batteries are relatively inexpensive; don’t take a chance with suspect batteries.
Checking battery status
There are two ways to check the battery status of the logger:
•Check the Bat Low light on the logger. This light blinks when the battery has 25% or less
capacity remaining.
•Check the status with logger software. For alkaline batteries, the status is displayed in the
percentage of capacity remaining. Lithium battery voltage is either listed as “good,” which
represents anywhere from 25 to 100% of capacity remaining, or “empty,” which represents 0 to
25% of capacity remaining. Lithium batteries have a relatively flat discharge curve, which means
the voltage does not vary much with use until they fail. Because of the uncertainty in capacity, it
is recommended that you start new launches with fresh lithium batteries that you know are at
100% rather than relying on old ones.
It is always recommended that you read out the logger before replacing batteries. If you replace the
batteries while the Micro Station is logging, it will stop recording data. The data will not be overwritten,
however, until the next launch.
Adding and removing sensors
Smart sensors plug into the logger and collect data about various weather parameters. Before you bring
the logger and sensors to the field, it is important that you gather and test all the sensors. Specifically, you
should:
•Plug in all the sensors you plan to use,

Chapter 3: Logger operation
14 HOBO Micro Station User’s Manual
•Make sure they are communicating, and
•Make sure the readings are valid.
To add a sensor, simply plug it into a sensor port on the logger. Follow these guidelines when adding
sensors:
•Never add or remove sensors while the logger is recording data. Sensors should only be added
while the logger is stopped, when configuring the launch parameters with logger software, or
after configuration but before the start of logging (if the logger was configured to start on a
specific date or time or by a push button start).
•Any sensors added while the logger is recording data will be ignored. Logging will continue
normally for other sensors. If a sensor is removed while logging, the Sensor Error status light will
blink when the next logging interval is reached. The data for that sensor will then display as
missing or erroneous in readouts.
•You cannot replace one sensor with a new sensor of the same type while logging. If you
would like to replace a sensor with another sensor of the same type (for example, swap a
temperature sensor with a new temperature sensor), it is necessary to read out the current data
from the logger and re-launch with the new sensor.
•The logger can work with a maximum of 100 meters (328 feet) of smart sensor network
cable, which is the digital communications portion of the sensor cables. If you are using multiple
sensors, be sure to check the length of each smart sensor network cable reported in the Sensor
Manuals. Add them together and make sure they do not exceed 100 meters (328 feet).
Time accuracy
Upon launch, the Micro Station’s clock is set in Coordinated Universal Time (UTC), which is determined
from the clock on your computer. Once the Micro Station is logging, it will keep fairly accurate time.
However, there are three main sources of errors with time reporting.
•Host clock error. A common source of error is an incorrect time in the computer used to launch
the logger. Make sure the clock on your computer is set to the correct date and time before
launching the logger. One resource for calculating accurate time settings for UTC (colloquially
known as Greenwich Mean Time or GMT) is the www.time.gov web site.
•Start-up error. The logger can lose as much as 2 seconds when it is launched. This is a one-time
error that occurs as part of the start-up sequence and cannot be avoided.
•Clock drift. The long-term time accuracy is a function of temperature. The worst-case error is
±8 parts per million (PPM) a week at 25°C, which is about 5 seconds per week. The error
increases as the temperature deviates from 25°C (see the figure below). If the temperature were a
constant -20°C, the logger time error could be as much as 35ppm (21 seconds per week).

Chapter 3: Logger operation
HOBO Micro Station User’s Guide 15
Worst case time error
Reading out the logger and relaunching it will reset the logger’s clock. This is useful when your logger
has been running for a while and its clock needs to be reset. Just be sure the computer clock is set
accurately before relaunching.
Logger memory
The logger uses non-volatile memory, which means it retains data indefinitely once power runs out.
Specifically, the logger uses a high-capacity Flash memory to store data, which can retain the data even
when the batteries are removed. This type of memory is very durable.
If the logger dies in the field from dead batteries, replace them and read out the logger immediately. Do
not relaunch the logger until the data has been recovered. If your logger is damaged, contact Onset
Computer because there is a chance the data can be recovered. Refer to Chapter 6 for information about
returning loggers for data recovery.
The logger contains 512K bytes of memory. Up to 10K of this memory is used to store the launch
configuration and deployment notes, leaving at least 502K bytes for data storage. The logger software
automatically estimates how long the logger will record data until the memory is full (the run time) based
on the logging interval and the number and type of sensors connected. In general, adding sensors
decreases running time while increasing the logging interval increases running time. In most applications,
battery life limits the duration of the data logging before memory capacity.
The following figure shows the expected run time for several logging intervals based on the total number
of bits in place, which is determined by adding together the bits per sample for each sensor measurement
parameter in your system. For example, a Micro Station with the following sensors is using 56 total bits.
1 Temperature X 8 = 8
1 Wind Speed X 16 = 16
2 Temperature/RH X 16 = 32
Total number of bits 56

Chapter 3: Logger operation
16 HOBO Micro Station User’s Manual
At a logging interval of 5 minutes, the memory run time for a Micro Station using 56 bits would be
approximately 250 days (based on the following figure). See the sensor’s manual for the number of bits
each type of sensor uses.
Memory run time