HOBO MX Water Level Logger (MX2001-0x) Manual
U.S. and International Sales: 1-508-759-9500 11
www.onsetcomp.com
Internal Event
Name Definition
Safe Shutdown
The battery level dropped below 1.85 V;
the logger performs a safe shutdown.
Setting a Logger Password
You can create an encrypted password for the logger that is
required if another device attempts to connect to it. This is
recommended to ensure that a deployed logger is not
mistakenly stopped or purposely altered by others. This
password uses a proprietary encryption algorithm that changes
with every connection. To set a password:
1.
Tap Devices. Tap the logger tile to connect to the logger.
2.
Tap Lock Logger.
3.
Type a password and then tap Set.
Only the device used to set the password can then connect to
the logger without requiring a password; all other devices are
required to enter the password. For example, if you set the
password for the logger with your tablet and then try to
connect to the logger later with your phone, you must enter
the password on the phone but not with your tablet. Similarly,
if others attempt to connect to the logger with different
devices, they are also required to enter the password. To reset
a password, press the button on the logger or connect to the
logger and tap Manage Password and tap Reset.
Maintenance
The logger requires the following periodic maintenance to
ensure optimal operation:
•
Protect the logger. This logger can be damaged by shock.
Always handle the top end and sensor end with care. The
sensors may lose their calibrated accuracy or can be
damaged if dropped. Use proper packaging when
transporting or shipping the logger.
Important:
Do not attempt to open the sensor end
housing!
Unscrewing the nose cone of the sensor end will
cause serious damage to the pressure sensor and logger
electronics. There are no user serviceable parts inside the
sensor end. Contact Onset Technical Support if the sensor
end requires servicing.
•
Periodically inspect the logger for biofouling
. Biological
growth on the face of the pressure sensor will impact the
pressure sensor’s accuracy. Organisms that grow inside the
sensor nose cone and on the sensor itself can interfere with
the sensor’s operation and eventually make the sensor
unusable. If the deployment area is prone to biofouling,
check the logger periodically for marine growth.
•
Be careful of solvents.
Check a materials-compatibility
chart against the wetted materials listed in the
Specifications table before deploying the logger in
locations where untested solvents are present. The logger
has Viton and Buna-N O-rings, which are sensitive to polar
solvents (acetone, ketone), ammonia, chlorine, and brake
fluids.
Compensating for Drift
All pressure sensors drift over time. The drift for the pressure
sensors and electronics in the logger is less than 0.5% FS (worst
case) per year. In most applications, drift is not a significant
source of error because the offset created by any drift is zeroed
out when you enter the reference water level in the app at the
beginning of each deployment. In effect, you are re-zeroing the
sensor each time you apply a reference reading to the data file.
Pressure sensor drift matters more when absolute pressure
values are needed, or if there are no recent reference level or
depth measurements available. For example, if the logger is
deployed for one year and no new reference level readings are
taken during the deployment, it is possible that the sensor
could have drifted as much as 0.5% FS by the end of the
deployment.
It is possible to determine the actual amount of drift during a
deployment if a reference level is taken at the beginning and
the end of a long-term deployment. The results of applying the
two different reference levels (once at the beginning of the
data file and again at the end of the data file) can be compared.
Any difference between the files indicates the amount of
sensor drift (assuming accurate reference levels). See
Reading
Out the Logger
for changing the reference water level in the
data file.
Verifying Accuracy
You can check the differential accuracy of the logger for water
level measurements by deploying the logger’s sensor end at
two depths and comparing the difference in level readings in
the data files. When verifying the accuracy this way, be sure to
allow the sensor’s temperature to stabilize at each depth.
You can check the absolute pressure accuracy by using the two
pressure sensors in the logger. Pull up the sensor end that is in
the water so that both the absolute and differential sensors are
in the air. Check the differential pressure with the app. The
differential pressure should be zero or less than the sum of the
error for the two sensors.
Battery Information
The logger requires two user-replaceable AA 1.5 V alkaline
batteries. Expected battery life varies based on the ambient
temperature where the logger is deployed, the logging or
sampling interval, frequency of offloading and connection to
the mobile device, number of channels that are active, alarm
duration, use of burst mode or statistics logging, and battery
performance. New batteries typically last 1 year with logging
intervals greater than 1 minute. Deployments in extremely cold
or hot temperatures, a logging interval faster than 1 minute, or
a sampling interval faster than 15 seconds can impact battery
life. Estimates are not guaranteed due to uncertainties in initial
battery conditions and operating environment.
To install or replace the batteries:
1.
Before changing the batteries, stop the logger and offload
any data.
Press this button to reset a
logger password
