SmartTemp SDI-12

Smart SDI-12/RS-485 Temperature Sensor (Soil)

Part # 51126

digital temperature sensor

Smart Temp is a high precision digital temperature sensor that meets USGS guidelines. It features the ability to automatically sample temperature and calculate minimum, maximum, and average temperatures on a flexible time scale.

This sensor is ideal for high-accuracy readings in water, soil, and air. It features fully-potted components, robust PVC Type II housing, and marine-grade stainless steel, making the sensor ideal for harsh environments.

SDI-12 output provides universal compatibility with any SDI-12- enabled data logger and low power applications, or use the standard SDI-12 command set over an RS-485 physical interface for applications that require long cable runs or many sensors.

  • NIST certification available
  • High-accuracy temperature measurement
  • Extremely low current draw
  • Works in water, soil, or air
  • Durable 316 grade stainless steel tine for easy soil insertion
  • Suitable for freshwater or marine applications
  • Fully potted electronics
  • Tough PVC Type II housing
  • Celsius, Fahrenheit, and Kelvin output
  • Digital—no calibration required

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What's the Easiest and Quickest Way to Start Collecting Data and Access it Anywhere?

The Answer's in the Cloud.

eTracker is a cellular modem and "virtual" cloud-based data logger in one (meaning you don't need to install a separate data logger). Simply connect your sensor and a power source to eTracker and you're done. Configure (or reconfigure) anytime from any Internet-connected device, and use Stevens-Connect to retrieve your data, or forward it to your favorite software system.

Technical Specifications


Silicon bandgap temperature sensor


SDI-12 v.1.4 and RS-485

Measurement range

-40° F to +140° F (-40° C to +60° C)


±0.18° F (±0.1° C) from 23° F to 122° F (-5° C to +50° C)
±0.2° C outside this range


0.01° C

Current draw

Idle: 10 μA (SDI-12), 0.6 mA (RS485)
Sample: 6mA for 10 ms
Transmit/receive: 6mA for ~ 100 ms (depends on length of data)
Peak: 30 mA for 1 ms during initial power-on


Celsius, Fahrenheit, and Kelvin


4.95” (125.7 mm) L x 0.7” (17.8 mm) ⌀ (#51126)
3.56” (90.4 mm) L x 0.70” (17.8 mm) ⌀ (#51163)