Hobo MX Series Manual page 9

• Once the high or low condition clears, the logging
interval time will be calculated using the last recorded
data point in burst logging mode, not the last data point
recorded in normal mode. For example, let's assume the
logger has a 10-minute logging interval and logged a data
point at 9:05. Then, the high limit was surpassed and
burst logging began at 9:06. Burst logging then continued
until 9:12 when the sensor reading fell back below the
high limit. Now back in normal mode, the next logging
interval will be 10 minutes from the last burst logging
point, or 9:22 in this case. If burst logging had not
occurred, the next data point would have been at 9:15.
• A New Interval event is created each time the logger
enters or exits burst logging mode. See Logger Events for
details on plotting and viewing the event.
Statistics Logging
During fixed logging, the logger records data for enabled
sensors and/or selected statistics at the logging interval
selected. Statistics are calculated at a sampling rate you specify
with the results for the sampling period recorded at each
logging interval. The following statistics can be logged for each
sensor:
• The maximum, or highest, sampled value,
• The minimum, or lowest, sampled value,
• An average of all sampled values, and
• The standard deviation from the average for all sampled
values.
For example, a logger is configured with the absolute pressure,
differential pressure, and water temperature sensors enabled,
and the logging interval set to 5 minutes. The logging mode is
set to fixed interval logging with Normal and all four statistics
enabled and with a statistics sampling interval of 30 seconds.
Once logging begins, the logger will measure and record the
actual absolute pressure, differential pressure, and water
temperature sensor values every 5 minutes as well as calculate
the water level and barometric pressure. In addition, the logger
will take readings for the enabled sensors every 30 seconds and
temporarily store them in memory. The logger will then
calculate the maximum, minimum, average, and standard
deviation using the samples gathered over the previous 5-
minute period and log the resulting values. When reading out
the logger, this would result in 17 data series: 5 sensor-related
series (differential pressure, absolute pressure, barometric
pressure, temperature, and water level with data logged every
5 minutes) plus 12 maximum, minimum, average, and standard
deviation series (four for differential pressure, four for absolute
pressure, and four for temperature with values calculated and
logged every 5 minutes based on the 30-second sampling).
Statistics are not available for barometric pressure and water
level data.
To log statistics:
1. Tap Devices. Tap the logger in the app to connect to it and
tap .
2. Tap Logging Mode and then select Fixed Logging.
3. Select Normal to record the current reading for each
enabled sensor at the selected logging interval.
1-508-759-9500 (U.S. and International)
1-800-LOGGERS (U.S. only)
HOBO MX Water Level Logger (MX2001-0x) Manual
Important: You must select Normal if you want to log water
level and barometric pressure data. If you deselect Normal, the
logger will not be able to calculate water level or barometric
pressure.
4. Select the statistics you want the logger to record at each
logging interval: Maximum, Minimum, Average, and
Standard Deviation (average is automatically enabled when
selecting Standard Deviation). Statistics will be logged for all
enabled sensors. In addition, the more statistics you record,
the shorter the logger duration and the more memory is
required.
5. Tap Statistics Sampling Interval and select the rate to use
for calculating statistics. The rate must be less than, and a
factor of, the logging interval. For example, if the logging
interval is 1 minute and you select 5 seconds for the
sampling rate, then the logger will take 12 sample readings
between each logging interval (one sample every 5 seconds
for a minute) and use the 12 samples to record the resulting
statistics at each 1-minute logging interval. Note that the
more frequent the sampling rate, the greater the impact on
battery life.
6. Tap Save.
7. Tap .
You can plot the statistics series once you read out the logger.
Note that the logger will always display the current sensor
readings in the app even if they are not being logged.
Updating the Reference Water Level and
Water Density
The logger calculates data based on the reference water level
and water density settings in the app. You may need to update
these settings during deployment. These are guidelines for
when to update reference water level or water density.
• The reference water level may need to be adjusted to
compensate for drift (see Compensating for Drift) or for
cable stretch in water level logger cables longer than 30
meters (100 feet). Check the reference reading in the first
couple of months of deployment when using a long cable
and update the reference water level as necessary. Once
stabilized, you should not need to reset the reference
water level for several months.
• If you realize during a deployment that the reference
water level and water density you entered are not as
accurate as needed, then you will need to update them.
• If you update the water density, you will also need to
enter a new reference water level reading. Once the new
values are entered and saved, a reading is taken and will
be used to calculate a new calibration constant that will
be applied to all data for the current deployment (both
before and after the new values are entered).
• If you only want to change future data, then stop the
current deployment, offload the data, and start a new
deployment with the new water parameters.
To change the reference water level or water density:
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