Overview

The MX2311 pairs research-grade sensing of multiple growing parameters with wireless convenience, integrating the renowned LI-COR LI-200R Pyranometer and the LI-300 and LI-350 Soil Moisture Sensors that deliver key measurements with scientific-grade accuracy (calibration uncertainty of ±3% typical).

This all-in-one device captures a comprehensive climate picture, describing the root-zone conditions that most directly influence water uptake, nutrient movement, plant stress, and irrigation decisions.  VWC tells you whether the root zone has enough water. Soil EC tells you whether dissolved salts in that water are becoming too concentrated. Combining an external LI-200R Pyranometer (measuring total solar irradiance in the 400-1100 nm range) and LI-300 Soil Moisture Sensor, along with built-in temperature and RH sensors, this multiparameter logger enables the calculation of critical metrics such as accumulated solar radiation (MJ/ m²), daily light integral (DLI of Solar, MJ/m²/day), vapor pressure deficit (VPD, kPa), EC, VWC and dew point.

IMPORTANT NOTE: For mounting, an M-PLT and 2003S Leveling Fixture are required. Mounting to poles or pipes require an M-BRK and 2003S.

Users can mount the sensor in the field, and setup and data retrieval are seamlessly simple—no cables or additional download devices needed using the free HOBOconnect app on your phone or tablet. Effortlessly configure the logger and download data via Bluetooth (up to a 100 ft range), which allows you to deploy in and download data from hard-to-reach spots.

Expand your remote monitoring by adding an MX Data Plan, which allows you to upload data to LI-COR Cloud remote software for further analysis, sharing, and more.

Features

Wireless Bluetooth Data Offload
Fast, easy logger setup and download via phone or tablet (up to ~100 ft range)

Research-grade Solar Radiation Measurements
Integrated LI-COR 200R sensor measures total solar irradiance in the 400–1100 nm range with ±3% typical calibration uncertainty

Integrated Temp & RH Monitoring
Logged temperature and humidity alongside solar radiation for a complete view of environmental conditions

Rugged, Weatherproof Design
Durable IP67/NEMA 6 housing stands up to humid, wet, and dusty environments found in greenhouses, growth chambers, or outdoor field sites

Long Battery Life & Memory
User-replaceable battery lasts up to ~2+ years and ample data storage supports extended deployments

Alarms and Alerts
See out-of-range conditions with logger’s LED readout, and configure threshold alerts using HOBOconnect for proactive monitoring

Easy Deployment
Users can deploy the logger in minutes, configure logging intervals via the HOBOconnect app, and wirelessly retrieve data (without a laptop) in the field!

Specifications

Temperature Sensor
Range
-40 to 70°C (-40 to 158°F)

Accuracy
±0.2 °C (typical) within -40 to 70 °C

Resolution
0.008°C (.014 °F)

Drift
<0.01°C (0.018°F) per year

Response Time* Without Solar Radiation Shield
17 minutes in air moving 1 m/sec

Response Time* With Solar Radiation Shield
24 minutes in air moving 1 m/sec

Relative Humidity (RH) Sensor
Range
0 to 100% RH, -40° to 70 °C exposure to conditions below -20°C (-4°F) or above 95% RH may temporarily increase the maximum RH sensor error by an additional 1%

Accuracy
±2.5% from 10% to 90% (typical) to a maximum of ±3.5% including hysteresis at 25°C (77°F); below 10% RH and above 90% RH ±5% typical

Resolution
0.01% RH

Drift
<1% per year typical

Response Time* Without Solar Radiation Shield
30 seconds in air moving 1 m/sec

Response Time* With Solar Radiation Shield
40 seconds in air moving 1 m/sec

Calculated Metrics
Vapor Pressure Deficit (VPD) in kPa, and Dew Point (computed from logged data)

Soil Moisture: Volumetric Water Content (VWC)
Measurement Range (select one at configuration)****
0.00 to 1.0 m³/m³ VWC in mineral soils
0.00 to 1.0 m³/m³ VWC in soilless media
Apparent Dielectric Permittivity: 1 (air) to 80 (water)

Accuracy
±0.03 m³/m³ typical
±0.06 m³/m³ maximum
Apparent Dielectric Permittivity: ±1 Ɛa

Resolution
0.001 m³/m³
Apparent Dielectric Permittivity: 0.002 Ɛa

Dielectric Measurement Frequency
70 MHz

Volume of Influence
1400 ml

Percent of Field Capacity (for VWC measurements only)
Range: 0 to 200%
Resolution: 0.1%

Soil Temperature*****
Measurement Range
-40 to 70°C (-40 to 158°F)

Accuracy
±0.5°C from -40° to -20°C
±0.3°C from -20°C to 70°C

Resolution
0.1°C (0.18°F)

Soil Bulk Electrical Conductivity (EC)
Measurement Range
0 to 20000 µS cm-1

Accuracy
±5 % from 0 to 10000 µS cm-1
±8 % from 10000 to 20000 µS cm-1

Resolution
1 µS cm-1

Global Solar Radiation (GSR) Sensor
Range
0 to 1280 W/m² (full sunlight)

Accuracy
±3% typical, ± 5% maximum (LI-200R Absolute Calibration)***

Offset
± 0.5 W/m²

Resolution
0.05 W/ m²

Spectral Range
400–1100 nm

Linearity
Maximum deviation of 1%

Stability
<= 2% change over one year

Temperature
-40 to 65°C (-40 to 149°F)

Temperature Dependence
±0.15% per ˚C maximum

Cosine Correction
Cosine corrected up to 82˚ angle of incidence

Azimuth
<±1% error over 360˚ at 45˚ elevation

Tilt
No error induced from orientation

Detector
High stability silicon photovoltaic detector (blue enhanced)

Sensor Housing
Weatherproof anodized aluminum case with acrylic diffuser and stainless steel hardware. O-ring seal on the sensor base.

Sensor Size
2.36 cm diameter x 3.63 cm (0.95” x 1.43”)

Cable Length
1.8 m

Calculated Metrics
Accumulated solar radiation in MJ/m², daily light integral (DLI) of solar

Logger
Operating Range
-40 to 70°C (-40 to 158°F)

Radio Power
1mW (0 dBm)

Transmission Range
Approximately 30.5 m (100 ft) line-of-sight

Wireless Data Standard
Bluetooth Low Energy (Bluetooth Smart)

Logging Rate
1 second to 18 hours

Logging Modes
Fixed interval (normal, statistics) or burst

Memory Modes
Wrap when full or stop when full

Start Modes
Immediate, push button, date & time, or next interval

Stop Modes
When memory is full, push button, date & time, or after a set logging period

Time Accuracy
±1 minute per month 0° to 50°C (32° to 122°F)

Battery Type
2/3 AA 3.6 Volt lithium, user replaceable

Battery Life
2 years, typical with logging interval of 1 minute and Bluetooth Always On enabled; 4 years, typical with logging interval of 1 minute and Bluetooth Always On disabled. Faster logging intervals and statistics sampling intervals, burst logging, remaining connected with the app, excessive downloads, and paging may impact battery life.

Memory
195,000 measurements, maximum

Full Memory Download Time
Approximately 4-5 minutes; may take longer the further the device is from the logger

Dimensions
Logger housing: 10.8 x 5.08 x 2.24 cm (4.25 x 2.0 x 0.88 in.)
Soil moisture sensor (only): 4.6 × 4.6 × 10.9 cm (1.81 × 1.81 × 4.31 in)
Soil moisture sensor needle length: 5.4 cm (2.14 in)
Soil moisture sensor needle diameter: 0.40 cm (0.16 in)
Sensor cable length: 2 m (6.56 ft)

Weight (Unpackaged)
333 g
11.8 oz
Weight (Packaged)
490 g
17.3 oz
Materials
Acetal, silicone gasket, stainless steel screws
Soil Moisture Sensor: ASA plastic body with polyurethane epoxy filling and stainless-steel pins
Cable: PVC, UV resistant and rodent repellent (soil moisture sensor cable)

Environmental Rating
Logger: NEMA 6 and IP67
Soil Moisture sensor and cable: xxxx

* Typical, up to 90% of change

** Per RH sensor manufacturer data sheet

*** Calibrated against an Eppley Precision Spectral Pyranometer (PSP) under natural daylight conditions. Absolute uncertainty under these conditions is ± 3% typical; ± 5% maximum.

**** The sensor data can be post-calibrated if necessary (e.g. the sensor is used in non-mineral soil types or higher than standard accuracy is required). Users can apply a calibration equation to the data exported from HOBOlink. The VWC range will depend on the calibration equation.

***** For additional accuracy, the sensor data can be post-calibrated for a particular soil by applying a calibration equation to the data exported from the app.