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OTT PLS - Pressure Level Sensor

Robust ceramic pressure transducer for water level measurement

The OTT PLS measures water level, depth to water, or pressure by means of an integrated controller and ceramic pressure-measuring cell. Design features such as multiple communication outputs (SDI-12 or 4 ... 20 mA), stainless steel housing, and a rugged cable make this sensor ideal for monitoring water level in a variety of applications.

  • Surface water, Groundwater
  • Vented pressure cell
  • Water level, Pressure, Temperature
  • Water level and temperature measurement - for use with external data logger
  • 0 … 4, 10, 20, 40, and 100 m
  • ± 0.05% FS
  • No
  • SDI-12, RS-485 (using SDI-12), or 4 … 20 mA
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  • The robust ceramic pressure cell offers industry-leading accuracy and does not deform over time like membrane technology, providing long-term measurement stability
  • Rugged design: Ceramic pressure cell resistant to physical force (5 x burst pressure) and enclosure made of high-quality saltwater resistant steel for use in coastal environments
  • Built-in microcontroller – compensates for temperature effects and applies correction values for gravitational acceleration and water density
  • Vented pressure probe, automatically compensates for changes in barometric pressure
  • Robust cable with Kevlar core for length stabilization and capillary tube for venting
  • Simple setup and connection to external dataloggers using SDI-12 or 4 ... 20 mA interfaces
  • Optimized resolution is achieved by assigning the 4 ... 20 mA to that part of the measuring range that is actually required
  • Water temperature output in addition to water level (for SDI-12 output)

Measuring water level in surface and groundwater, including:

  • Stations with sloping bottom, e.g. water banks
  • Small diameter pipes or holes (from 1" Ø)
  • Dams, weirs, irrigation systems
  • Waterways that occasionally ice over
  • Brackish water, saltwater
  • Waterways that do not contain water throughout the year (e.g. retaining basins)
Brochure - OTT Water level measurement
Leaflet - Pressure Probe OTT PLS
netDL Templates - Configuration - for OTT Data Logger Operating Program
Templates for netDL Configuration shown in the OTT netDL configuration videos
Operating instructions Pressure Probe OTT PLS
OTT netDL - Configuration - OTT PLS via OTTSDI - Video EN
OTT PLS - CE Konformitätserklärung | Declaration of Conformity | Declaration de Conformité
OTT PLS - DIN EN ISO 4373 Declaration of Conformity | Declaration de Conformité | Konformitätserklärung
OTT PLS CSI specifications
Supplement to operating instructions Pressure Probe OTT PLS – Plug-in pressure probe cable
Technical Note - Sensor Selection Guide Groundwater
Technical Note - Sensor Selection Guide Surface Water
White Paper - OTT ecoLog Guidance: Remote communication via mobile networks
Whitepaper - OTT ecoLog Guidance: Remote communication via mobile networks
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Water level measurement
Measurement range 0 ... 4 m, 10 m, 20 m, 40 m, 100 m
 SDI-12 ±0.05 % FS (linearity and hysteresis)
 4 ... 20 mA ±0.1 % FS (linearity and hysteresis)
10 ppm/°C at 20 °C
Resolution (SDI-12) 0.001 m; 0.1 cm; 0.01 ft; 0.1 mbar; 0.001 psi
Temperature compensated working range  -5 °C ... +45 °C (ice-free)
Temperature measurement range –-25 °C ... +70 °C (ice-free)
Resolution 0.1 °C / 0.1 °F
Accuracy ±0.5 °C / ±0.9 °F
Electrical data
Available interfaces (use as required) 4 ... 20 mA, SDI-12, RS485 (via SDI-12 protocol)
Supply voltage +9.6 ... +28 V DC, typically 12/24 V DC
Power consumption (SDI-12)
Sleep <600 µA
Active <3.6 mA
Pressure sensor (capacitive pressure sensor) ceramic, temperature compensated, overload safe for up to 5 times the measuring range without permanent mechanical damage
Temperature sensor NTC
Dimensions 195 mm x 22 mm
Weight approx. 0.3 kg
Environmental conditions
Operating temperature –-25 ... +70 °C
Storage temperature –-40 ... +85 °C
Housing stainless steel 1.4539 (904L) resistant to sea water
Seals Viton
Cable jacket PUR
Protection type IP68
Mechanical Strength meets the mechanical shock tests of IEC 68-2-32
EMC limits CE conformity; EN 61000-4-2/3/4/5/6 and EN 61000-6-3 Class B are adhered to
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How do I communication with my sensor using the RS-485 interface?

Communication on this interface follows the SDI-12 protocol. This follows a specific timing which is defined by the SDI-12 standard. Please find detailed information in the attached/linked document. The sensor wont react to simple ASCII commands send through this interface as they do not conform to the SDI-12 standard.

Regarding PLS Sensor: The RS-485 interface might not be active by default. In this case it needs to be activated using the SDI-12 interface of the sensor. Our HydroService will assist you in this matter (

Regarding CBS Sensor: The active interface of the sensor is determined by dip switches on the device. Please follow the sensor instruction to active the RS-485 interface.

Learn more about the datalogger implementation via RS-485