OTT RLS – Radar Level Sensor


Building on years of experience with the robust and accurate OTT PLS, the PLS 500 water level monitoring solution adds innovative metadata and internal sensors to remotely verify device performance providing peace of mind for long term deployment

The OTT PLS 500 measures water level, depth to water, or pressure by means of an easy to maintain, ceramic pressure cell. This highly accurate sensor includes design features such as four internal compensations, stainless steel housing, and a rugged cable making it ideal for monitoring water level in a variety of applications. Common communication protocols (SDI-12 and Modbus RTU) allow for seamless integration with external data loggers. The accurate temperature measurements and built-in microcontroller compensate for environmental changes in water density. Built-in QA/QC and metadata along with reduced sensor drift allow you to have full confidence in your long-term data.

Custom Cable
All PLS 500s are manufactured with cables cut to the users specifications upon order. Please specify the length of cable (meters or feet) that you require with any quoted item.



High performance

Measurements are unaffected by air temperature, humidity, flood events, floating debris, or contaminated water; reduces the likelihood of missing data and reduces data post processing

Low maintenance

Flat antenna design eliminates nesting areas for insects and periodic maintenance requirement.

Simple installation​

Light weight compact design facilitates easy mounting on bridges, extension mounting bracket or inside a small protective housing.

Low profile design​

Unobtrusive appearance is ideal for urban installation sites or sites prone to vandalism.

Flexible integration/Easy setups​

Connects to most data loggers via standard communication interfaces, SDI-12 or 4-20 mA; no need for additional PC software.

Low power consumption

Ideal for remote or solar powered sites; requires only 12 mA when active.

Technical Attributes


Housing MaterialASA (UV-stabilized ABS)
InterfaceSDI-12, RS-485 (using SDI-12), or 4 -20 mA
Level AccuracySDI-12:
1.3 – 6.6 ft: ± 0.03 ft (0.4 – 2 m: ±1 0 mm)
6.6 – 98.5 ft: ± 0.01 ft (2 – 30 m: ± 3 mm)
98.5 – 115 ft: ± 0.03 ft (30 – 35 m: ±1 0 mm)4 – 20 mA:
±0.1 % full scale
Measurement Time2 – 20 sec
Measuring Range1.3 – 115 ft (0.4 – 35 m)
Operating Frequency25.3 GHz
Operating Temperature Range-40 – +140 °F (-40 – +60 °C)
Power ConsumptionActive:
˂ 180 mW (˂ 15 mA at 12 V)
˂ 0.6 mW (˂ 0.05 mA at 12 V)
Power Supply5.4 – 28 V DC, typ. 12/24 V DC
Protection ClassIP 67
Resolution0.01 ft; 0.001 psi (1 mm; 0.1 mbar)
Standard storage temperature-40 – +185 °F (-40 – +85 °C)
Transmission power< 5 mW
Width of Beam12 ° (±6 °)