CS655-LC 12 cm Water Content Reflectometer for ET107

Overview

The CS655-LC is a multiparameter smart sensor that uses innovative techniques to monitor soil volumetric-water content, bulk electrical conductivity, and temperature. This sensor is used with the ET107 Weather Station.

Note: The cable connector for this sensor is suitable for use with an ET107 station. For other cable termination options, use the CS655 sensor instead.

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Detailed Description

The CS655-LC consists of two 12-cm-long stainless steel rods connected to a printed circuit board. The circuit board is encapsulated in epoxy and a shielded cable is attached to the circuit board for data logger connection.

The CS655-LC measures propagation time, signal attenuation, and temperature. Dielectric permittivity, volumetric water content, and bulk electrical conductivity are then derived from these raw values.

Measured signal attenuation is used to correct for the loss effect on reflection detection and thus propagation time measurement. This loss-effect correction allows accurate water content measurements in soils with bulk EC ≤8 dS m-1 without performing a soil-specific calibration.

Soil bulk electrical conductivity is also calculated from the attenuation measurement. A thermistor in thermal contact with a probe rod near the epoxy surface measures temperature. Horizontal installation of the sensor provides accurate soil temperature measurement at the same depth as the water content. Temperature measurement in other orientations will be that of the region near the rod entrance into the epoxy body.

Specifications

Sensing Volume 3600 cm3 (~7.5 cm radius around each probe rod and 4.5 cm beyond the end of the rods)
Electromagnetic CE compliant (Meets EN61326 requirements for protection against electrostatic discharge and surge.)
Operational Temperature -10° to +70°C
Sensor Output SDI-12; serial RS-232
Measurement Time 3 ms to measure; 600 ms to complete SDI-12 command
Power Supply Requirements 6 to 18 Vdc (Must be able to supply 45 mA @ 12 Vdc.)
Maximum Cable Length 610 m (2000 ft) combined length for up to 10 sensors connected to the same data logger control port
Rod Spacing 32 mm (1.3 in.)
Ingress Protection Rating IP68
Rod Diameter 3.2 mm (0.13 in.)
Rod Length 120 mm (4.7 in.)
Probe Head Dimensions 85 x 63 x 18 mm (3.3 x 2.5 x 0.7 in.)
Cable Weight 35 g per m (0.38 oz per ft)
Probe Weight 240 g (8.5 oz) without cable

Current Drain

Active (3 ms) 45 mA typical @ 12 Vdc (80 mA @ 6 Vdc, 35 mA @ 18 Vdc)
Quiescent 135 µA typical @ 12 Vdc

Electrical Conductivity

Range for Solution EC 0 to 8 dS/m
Range for Bulk EC 0 to 8 dS/m
Accuracy ±(5% of reading + 0.05 dS/m)
Precision 0.5% of BEC

Relative Dielectric Permittivity

Range 1 to 81
Accuracy
  • ±(3% of reading + 0.8) from 1 to 40 for solution electrical conductivity ≤ 8 dS/m
  • ±2 (from 40 to 81 for solution electrical conductivity ≤ 2.8 dS/m)
Precision < 0.02

Volumetric Water Content

-NOTE- Using Topp Equation (m3/m3)
Range 5% to 50%
Accuracy ±3% VWC (typical in mineral soils that have solution electrical conductivity ≤ 10 dS/m)
Precision < 0.05%

Soil Temperature

Range -10° to +70°C
Accuracy ±0.5°C (for probe body buried in soil)
Precision ±0.02°C

Compatibility

Note: The following shows notable compatibility information. It is not a comprehensive list of all compatible or incompatible products.

Miscellaneous

Product Compatible Note
ET106 (retired)
ET107 (retired)
METDATA1 (retired)
RAWS-H (retired)
RAWS-P (retired)

Additional Compatibility Information

RF Considerations

External RF Sources

External RF sources can affect the probe’s operation. Therefore, the probe should be located away from significant sources of RF such as ac power lines and motors.

Interprobe Interference

Multiple CS655-LC probes can be installed within 4 inches of each other when using the standard data logger SDI-12 “M” command. The SDI-12 “M” command allows only one probe to be enabled at a time.

Installation Tools

14384 Pilot Tool

The 14384 Pilot Tool has rods with similar diameters and the same spacing as the probe. The tool can be driven into the soil using force levels that might damage the probe. After removing the 14384, the probe is inserted into the established holes.

14383 Installation Tool

The 14383 Installation Tool can be used to help maintain the proper spacing and parallel orientation of rods during insertion. Use of the 14383 may reduce measurement errors by minimizing soil disturbance.

Downloads

CS650 / CS655 Firmware v.2 (429 KB) 02-12-2015

Current CS650 and CS655 firmware. 

Note:  The Device Configuration Utility and A200 Sensor-to-PC Interface are required to upload the included firmware to the sensor.

View Update History

Frequently Asked Questions

Number of FAQs related to CS655-LC: 3

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