HOBO MX801 Submersible Logger Quick Start Guide

Overview

The HOBO MX801 Submersible Logger is designed for use with compatible HOBO W-Series sensors to log water parameters such as temperature, conductivity, and depth. This logger must be deployed with sensors attached, as it is not waterproof without them. For deployments with two sensors, a 2-sensor adapter is required; consult the adapter's manual for attachment instructions.

The following steps outline the process for configuring and deploying your logger:

1. Connect a Sensor
2. Calibrate the Sensor
3. Configure Your Logger
4. Deploy the Logger
5. Download Your Data
6. Process the Data

Connect a Sensor to the Logger

1. Remove the rubber cap from the end of the logger.
2. Connect the sensor to the logger by aligning the alignment pin on the sensor with the hole on the logger connector. Do not force the connection to avoid bending any pins.
3. Attach the tapered coupler over the connection between the sensor and the logger. Ensure the magnetic fob is attached to one half of the tapered coupler. Snap one side of the coupler over the connection, with the tapered end toward the sensor. Slide the other half of the tapered coupler over the connection and press the two parts together until they snap.

Diagram illustrating the connection of the sensor to the logger using a two-part tapered coupler. One part of the coupler has a magnetic fob, and both parts are designed to snap together securely around the sensor and logger connection.

4. Tighten the tapered coupler screws with the included allen wrench. You may need to move the magnetic fob aside.
5. Insert the magnetic fob into its designated spot on the coupler.

Download and Open HOBOconnect

HOBOconnect is required for use with HOBO MX Series loggers. Download HOBOconnect from: www.onsetcomp.com/products/software/hoboconnect

Calibrate the Sensor

For conductivity, CTD, or DO sensors, calibrate them in your office or lab before logger configuration for deployment. The HOBOconnect app guides you through basic calibration steps. For optimal calibration accuracy, refer to the sensor calibration sections in the HOBO MX800 Series User's Guide.

Configure Your Logger

Logging Water Level Requires Barometric Pressure

If using the MX801 logger with a CTD sensor to measure water level, deploy a barometric pressure logger nearby (within 10 miles) to log barometric pressure changes. Compatible loggers include the HOBO MX802 or HOBO MX2001. These require a sensor for weatherproofing, or a termination plug (W-PLUG) for the MX802. HOBOconnect uses barometric pressure data with CTD pressure data to calculate water level.

Use HOBOconnect to configure the logger for barometric pressure recording:

1. If using an MX802 logger, you may need to wake it using the magnetic fob.
2. Configure the Logging Interval and Start Logging settings to match those used for the MX801 logger with the CTD sensor. Ensure this logger continues until after the CTD logger is stopped or its data is downloaded.
3. Confirm that the Barometric Pressure channel is On.
4. Refer to the HOBOconnect User's Guide for more detail.

Configure and Start the HOBO MX801 Logger Using HOBOconnect

1. You may need to wake the MX801 logger using the magnetic fob.
2. Configure the Logging Interval and Start Logging settings to match those used for barometric pressure logging.
3. Tap Temperature and ensure it is set to On. For water level recording, Absolute Pressure must also be set to On. Adjust other measurement channels as needed. To record Specific Conductivity, select the channel and enter the temperature coefficient for the deployment water, which typically differs from calibration solution coefficients.
4. Refer to the HOBOconnect User's Guide for more detail.

Deploying Your Logger

1. Deploy the MX801 logger in water at the site. Refer to the HOBO MX800 Series User's Guide for mounting recommendations.
2. If logging water level, deploy your barometric pressure logger.
3. Allow the MX801 logger time to reach temperature equilibrium and take a reference water level reading. Record this reading and its time in your deployment notes. This reference reading is necessary for post-processing data in HOBOconnect.

Download the Data

1. At the end of deployment, it is recommended to take measurements of critical water parameters and note these values and their times. This information can aid in data validation and correction.
2. Retrieve the logger from its deployment location.
3. In HOBOconnect, tap the MX801 tile and download data.
4. If redeploying the logger, clean the sensor if necessary before the next deployment.
5. If a barometric pressure logger was also deployed, download its data using the same device. Process data from both loggers after downloading.

Processing Your Data

1. Select the Data tab.
2. Open the MX801 data file that was just downloaded.

To derive water level, follow steps 3-9:

1. Click the Reference Water Level icon. The Water Level Assistant opens.
2. Select a listed Water Density or enter one manually.
3. Select the "Use Reference Water Level" check box.
4. Enter the Reference Water Level recorded during logger deployment.
5. Select the date and time closest to the Reference Water Level measurement.
6. Select the file containing barometric pressure data or enter a fixed pressure.
7. Click Proceed after entering the information. HOBOconnect will calculate the water level data channel. Export the data file to save this water level data and the barometric pressure data used.

Files can be exported and shared. Sharing is available only on the mobile app.

Dissolved oxygen (DO) data can be processed with data from a nearby conductivity logger to obtain salinity-adjusted DO, or with barometric pressure data from a nearby logger to get DO in percent saturation. For more information, refer to the HOBO MX800 Series User's Guide.

For specifications, complete mounting guidelines, and other details about this logger, refer to the full product manual at: www.onsetcomp.com/resources/documentation/25707-mx800-user-guide