Technical Note — Senix Ultrasonic Level Sensor (with Observant C3)

Observant Support

Created: ; updated: .


The Senix ultrasonic level sensor measures distance to the surface of water, allowing accurate measurement of water level.

As part of an Observant system, the device can be used to:

  • Display current and historical water level.
  • Trigger alarms on preset high or low water levels.
  • Automate pump operation to keep a tank or other water storage full.

Observant Global view of water level data from the Senix ToughSonic sensor:




Typical applications are:

  • Water level monitoring in tanks,
  • Water level monitoring dams,
  • Water level monitoring turkeys nests*,
  • Water level monitoring channels.

*Australian a small earth dam adjacent to, and higher than, a larger earth dam, to feed water by gravity to a cattle trough, etc. — Collins English Dictionary

Supported Models

Senix 13ft/4m Ultrasonic Level Sensor for C3 Tank Kit: Item 01463

Senix 13ft/4m Ultrasonic Level Sensor with 2m Bare Ends: Item 00760


Description: Senix ultrasonic level sensor with maximum depth range 4.3 meter. Rugged, small form factor, non contact level sensing ideal for all water level applications: tank, dam, channel, bay.


Connection to Field Unit Ports

Field Unit Port  Interface cables and Connectors
 C3 RS485 Sensor supplied with a 4-pin connector appropriate for C3 RS485 port


Bare Wire Connections 

In advanced installations, the sensor's bare wires can be connected to an Observant C3 RS485 port directly:

Port Terminal Sensor Wire Colour
Power Brown
RS485A Yellow
RS485B Grey
Ground Blue


For a detailed illustrated guide, see Installation Guide — C3 Tank Level Monitoring Kit.

These notes must be observed when installing the sensor. Failure to observe them can result in inaccurate or erratic measurement of the water level.

  • The sensor must be mounted facing directly downwards, with an unobstructed view of the water surface
  • The sensor must be mounted away from the tank wall or any other obstruction. Clearance from the sensor to the tank wall must be a minimum of 15% of the tank height. For example, if mounted in a tank whose total height is 3m (9ft10in) then the sensor must be mounted at least 45cm (18in) away from the tank wall.
  • Due to the minimum distances that the sensors can accommodate, with the C3 Tank Kit, the bottom of its sensor should be no less than 4" from the highest level to be measured.
  • The C3 Tank Kit requires a hole of 2” (50mm) in diameter


For new customers, see how to Sign Up for the Observant Global Software Platform with a C3 Tank Level Monitoring Kit.

If you already have an Observant Global account, remember to add your new tank kit to your portfolio as described in Adding New EquipmentWhen adding the device in Global, choose PortA if sensor is connected to RS485 1 port or PortB if sensor is connected to RS485 2 port.   

Manuals, Links and Downloads


A detailed manufacturer's user manual may be found here.

Relevant Articles


OBS-USR-M007-R3,  C3 Tank Monitoring Kit Installation Guide, is available online for printing and downloading.

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