Acclima - Model TDR-310N - Precision Soil Water Content Sensor

- Housing designed for easy bore hole installation at any depth
- Larger sampling volume with the 10cm waveguides
- Soil Smart analysis works with all mineral soil types
- Incident Wave Amplitude: 2.3 V
- 20% to 80% Incident Wave Rise Time: 300 ps
- Waveform Digitizing Resolution: 5 ps
- SDI-12 Interface
- 3-element 10cm stainless steel waveguide
- 5m or 10m 3-conductor waterproof cable (standard)
- Waterproof Epoxy-filled Housing

Measurement Functions:
Volumetric Water Content: 0% to 100%
Medium Permittivity: 1 to 85
Medium Bulk Electrical Conductivity: 0 to 3000 µS/cm
Medium Temperature: -40 to +55 degrees C
Pore Water EC (Hilhorst Model): 0 to 55000 µS/cm
Measurement Performance:
Parameter Min Max Units
RELATIVE PERMITTIVITY
Range 1 85 -
Resolution 0.1 -
Repeatability (RMS deviation) 0.14 -
Accuracy -2 +2 %FS1
Stability with Bulk Electrical Conductivity (0-3000 uS/cm) -1 +1 -
VOLUMETRIC WATER CONTENT (VWC)
Range2 0 100 %
Resolution 0.1 %
Repeatability (RMS deviation) 0.3 %
Accuracy -3 +3 %FS
Stability with Bulk Electrical Conductivity (0-3000 uS/cm) -1 +1 %FS
TEMPERATURE4
Range -40 +55 °C
Resolution 0.1 °C
Repeatability (RMS deviation) 0.01 °C
Accuracy (+5 to +35 °C) -0.25 +0.25 °C
Accuracy (-15 to +55 °C) -0.5 +0.5 °C
BULK ELECTRICAL CONDUCTIVITY (BEC)
Range 0 3000 uS/cm
Resolution 1 uS/cm
Repeatability (RMS deviation) 3 uS/cm
Accuracy (0 – 1000 uS/cm) -25 +25 uS/cm
Accuracy (1000 – 2500 uS/cm) -2.5 +2.5 %
Accuracy (2500 – 3000 uS/cm) -5 +5 %

Absolute Maximum Ratings:
Stresses beyond those specified below may cause permanent damage to the sensor. These are stress
ratings only and operation at these levels is not implied.
Parameter Min Max Units
Supply Voltage (Measured between the red and white wires) -16 +16 Volts
SDI-12 Data Voltage (Blue-White wires) -16 +16 Volts
External Voltage Applied to sensor rod -0.3 +4 Volts
Electrostatic discharge, center rod IEC 61000−4−2 (ESD)
Storage Temperature (e.g. in air on a shelf, not in any media) -40 +60 °C
-40 +140 °F
Operating Conditions:
Parameter Min Max Units
Operating Supply Voltage +4.2 +15 Volts
Prior to 2H 2022 +6.5
Operating Temperature (VWC errors due to ice) -30 +55 °C
Operating Temperature (VWC accurate, no ice allowed) 0 +55 °C
POWER CONSUMPTION
Idle Current (sensor powered but inactive, 20 °C) < 10 uA
Idle Current (-35 to +50 °C) < 50 uA
Sensor read time 0.4 typical sec
Sensor read current (Supply Voltage = 12V) 118 typical mA
Sensor read current (Supply Voltage = 7V) 150 typical mA
Sensor communications current 6 typical mA
SDI-12 Data Line Electrical Characteristics:
Parameter Min Max Units
INPUT (when sensor is idle or receiving data)
Resistance to GND 160k 175k Ohms
VIL (required input voltage in “marking” state) -1 1.3 V
VIH (required input voltage in “spacing” state) 3.2 6 V
OUTPUT (when sensor is transmitting data)
Output impedance 1000 1250 Ohms
VOL (output voltage in “marking” state) 0 0.25 V
VOH (output voltage in “spacing” state) 4.7 5.2 V
Physical Characteristics:
Dimensions (without cable) 20 cm x 3.3 cm
Weight (without cable) 132 g
Cable weight 32.7 g/m
Composition 316 Stainless Steel, Epoxy, ABS Plastic
Cable 3 copper conductor, 22 Ga., waterproof and UV
resistant PVC jacket, 4.8mm overall diameter
Communication Protocol SDI-12 Version 1.4