HOBOnet TEROS 12 Soil Moisture/Temp/EC Sensor

SKU: RXW-T12-921


The HOBOnet TEROS 12 is a wireless sensor that works with the HOBOnet system to not only provide advanced soil moisture (volumetric water content) measurements with better accuracy and precision but also measure soil temperature and electrical conductivity. Designed to withstand harsh environmental conditions, these durable sensors last up to 10 years, so you can leave them in the field for extended periods of time. Sharpened stainless-steel probe tips make installation easy, even in hard soil, and a large volume of influence provides more accurate results.

The HOBOnet system is a cost-effective and scalable wireless sensor network for web-enabled monitoring of field conditions for applications such as crop management, research, and greenhouse operations. And because it’s wireless, you can deploy a network of sensors to easily monitor multiple points with a single system, while avoiding the risk of long cables that can interfere with field operations and are potentially vulnerable to nearby lightning strikes.

Sensors are easily linked to the network, and data can be accessed through HOBOlink®, Onset’s innovative cloud-based software platform.

Highlighted Features

  • Soil moisture (volumetric water content), soil temperature, and electrical conductivity measurements with one device
  • Sensor lasts up to 10 years in the field
  • Largest volume of influence (1010 mL) relative to sensor size, resulting in more accurate soil moisture measurements
  • Easy installation with sharpened stainless-steel probes that are more resistant to damage/deterioration
  • Less sensor-to-sensor variability

In what environment does this sensor operate?

This sensor operates in an outdoor environment.

What measurements does this sensor support?

The RXW-T12-921 sensor supports the following measurements: Electrical Conductivity (soil), Soil Moisture and Soil Temperature


Important Info:

A complete system requires at least one HOBO RX Remote Monitoring Station, a HOBOnet Wireless Manager (RXMOD-RXW-921), and a HOBOnet Wireless Sensor. HOBOnet Wireless Repeaters (RX-RPTR-921) can be added to extend the range.

Wireless Mote


Operating Temperature Range

-25° to 60°C with rechargeable batteries
-40 to 70°C with lithium batteries

Radio Power

12.6 mW (+11 dBm) non-adjustable

Transmission Range

Reliable connection to 457.2 m (1,500 ft) line of sight at 1.8 m (6 ft) high
Reliable connection to 609.6 m (2,000 ft) line of sight at 3 m (10 ft) high

Wireless Data Standard

IEEE 802.15.4

Radio Operating Frequencies

921 Mhz

Modulation Employed

OQPSK (Offset Quadrature Phase Shift Keying)

Data Rate

Up to 250 kbps, non-adjustable

Duty Cycle


Maximum Number of Motes

50 motes per one RX Wireless Sensor Network

Battery Type/ Power Source

Two AA 1.2V rechargeable NiMH batteries, powered by built-in solar panel or two AA 1.5 V lithium batteries for operating conditions of -40 to 70°C

Battery Life

With NiMH batteries: Typical 3–5 years when operated in the temperature range -20° to 40°C and positioned toward the sun (see Deployment and Mounting), operation outside this range will reduce the battery service life With lithium batteries: 1 year, typical use


16 MB


Sensor: 7.47 x 9.4 x 2.39 cm (2.94 x 3.7 x 0.94 inches)
Sensor needle length: 5.4 cm (2.13 inches)
Sensor needle diameter: 0.32 cm (0.13 inches)
Cable length: 5 m (16.4 ft)
Mote: 16.2 x 8.59 x 4.14 cm (6.38 x 3.38 x 1.63 inches)


RXW-T12-xxx sensor and cable: 245 grams (8.64 oz)
Mote: 223 g (7.87 oz)


Sensor: UV-stabilized ABS plastic housing; tipping bucket mechanism with magnetic reed switch pivots on metal shaft
Mote: PCPBT, silicone rubber seal

Environmental Rating

Mote: IP67, NEMA 6

Soil Moisture: Volumetric Water Content (VWC)


Dielectric Measurement Frequency

70 Mhz

Temperature Sensor


Measurement Range

-40 to 60°C


±0.5°C from -40 to 0°C
±0.3°C from 0 to 60°C



Data Sheet




Quick Start Guide