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Enabling better global research outcomes in soil, plant & environmental monitoring.

Smart PT

Smart SDI-12 / RS-485 Pressure, Temperature, and Digital Crest Gauge Sensor.

Stevens’ Smart PT is a ceramic membrane pressure and temperature sensor that delivers accurate results for a wide range of fluid level measurement applications. In addition to simple instantaneous measurements, this smart sensor features the ability to capture peak crest levels, and to automatically sample and report basic statistics on a configurable time interval.


  • < ± 0.1% full scale accuracy
  • Aluminium oxide ceramic membrane
  • Digital output (SDI-12 / RS485)
  • Depth scales available from 2 meters (6.6 feet) up to 200 meters (660 feet)
  • Rugged housing and fully potted electronics – no risk of leaking
  • Compact size
  • Not damaged by freezing water
  • Vented or non-vented cable, user specified length
  • Direct pipe connection option
  • Low power consumption
  • Lightning protection
  • Overpressure tolerant


Utilising the SmartPT Sensor in a custom IoT (Internet of Things)

The SNiP-SPT is a ‘Sensor Node Integrated Package’ for LoRaWAN or CAT-M1 communication of real-time salinity, TDS, conductivity and temperature measurements for continuous water quality monitoring.

The base SNiP-SPT integrates 1x SmartPT Sensor with 1x S-NODE to a site’s unique network, communication and power requirements. The S-NODE can support an added 3x compatible sensors.

A corrosion-resistant stainless steel housing and potted electronics make Smart PT extremely durable and long lasting for submersible water applications.

Smart PT is available with a vented or absolute pressure sensing module. Both versions come equipped with user specified length of cable. The vent tube provides an atmospheric reference which compensates for variations in barometric pressure.

In addition to programmable corrections for local variations in Earth’s gravitational field, Smart PT also compensates automatically for the water temperature-density dependency.

Every Smart PT provides both SDI-12 and RS-485 digital interfaces. Compatible with existing power and data logging instruments, the sensor can easily be deployed for data collection at remote monitoring sites.

Unique Abilities

  • Average and standard deviation outputs on up to 3600 autosampled data points over configurable time window. Data is stored until requested using the M2 command.
  • Crest gauge function automatically captures minimum and maximum level and number of seconds since the event.
  • Smart autosampling can provide smoothing and oversampling.
  • Custom offsets.
  • Environmental corrections for local gravitational field and changes in fluid density due to temperature.
Supply voltage 6 – 28 VDC (12 VDC typical)
Current consumption Average, SDI-12, one measurement per minute: 0.9 mA
Average, RS-485, one measurement per minute: 1.5 mA
Peak current, during response to host: 30 mA
Output SDI-12 (Version 1.4) and RS-485
Selectable output: Pressure in bar, kPa, psi or water depth in m, cm, ft.
Temperature in °C or °F
Operating temperature -20°C to 80°C (-4°F to 176°F)
Storage temperature -40°C to 80°C (-40°F to 176°F)
Pressure accuracy ± 0.1% of full scale
Temperature accuracy ± 0.25°C (0.45°F)
Wiring Red: 6 – 28 Vdc, Black: GROUND, Blue: SDI-12, White: RS-485 A/+, Green: RS-485 B/-
Cable High durability polyurethane (26 AWG)
Pipe threading M14-1
Dimensions 86.4 mm x 22.1 mm (3.4 in x 0.9 in)
Body material 316L Stainless Steel
Weight Probe: 120 g (4.23 oz.)
Cable: 40 g per m (0.43 oz. per ft)