6527 Starflow QSD

The Unidata 6527 Starflow QSD SDI-12 and Modbus Instrument is used to measure water velocity, depth and temperature of water flowing in rivers, streams, open channels and large pipes. When used with a companion Unidata IP data logger, flow rate and total flow can also be calculated.

The 6527 Instrument is robust, reliable and easy to use. It is completely sealed against water ingress, low maintenance, low power, no calibration and no fussy power arrangements required.

Ultrasonic Doppler Principle in Quadrature Sampling Mode is utilised to measure water velocity. The 6527 Instrument transmits ultrasonic energy through its epoxy casing into the water. Suspended sediment particles or small gas bubbles in the water reflect some of the transmitted ultrasonic energy back to the 6527 Instrument’s ultrasonic receiver instrument that processes this received signal and calculates the water velocity.

 Physical Specifications

Material Epoxy-sealed body, Marine Grade 316 Stainless Steel Mounting Bracket
Size 135mm x 55mm x 22mm (LxWxH)
Weight 1kg with 15m of Cable
Operating Temperature 0°C to 60°C water temperature


Velocity and Depth Specifications

Velocity Range 20mm/s to 0.8m/s
20mm/s to 1.6m/s in one direction (default)
20mm/s to 3.2m/s
20mm/s to 13.2m/s
Bidirectional velocity capability, set using configuration tools
Velocity Accuracy ±1% typical
Depth Range Ultrasonic Sensor 20mm up to 5m above top surface of the instrument
40mm up to 5m from the base of the instrument
Depth Accuracy Ultrasonic Sensor Typical ± 1%
Depth Range Absolute Pressure Sensor 0 to 10m
Depth Accuracy Absolute Pressure Sensor Typical ± 0.19% for 0m to 5m range
Typical ± 0.38% for 0m to 10m range
Temperature 0°C to 60°C
Temperature Resolution 0.1°C
Flow Computation Flow rate, totalised flow with companion NRT/NRL
Channel Type Pipe, open channel, natural stream
Cable 15 metre, 6 way
Cable Options User specified up to 50 metres


Electrical Specifications

Power Source Typical External Battery 12V – 24V DC
Power Usage 10V to 24V DC, 50µA standby, 100mA active for 1 sec
SDI-12 SDI-12V 1.3 recorder (1200 baud smart instrument channel)
RS 485 Modbus RTU