The CS625 measures the volumetric water content from 0% to saturation. It is similar to our CS616 but is designed specifically for CR200(X) and CR300-series dataloggers. This reflectometer has a 0 to 3.3 V square wave frequency output that our CR300 and CR200(X)-series dataloggers can measure.Read More
The CS625 consists of two 30-cm-long stainless steel rods connected to a printed circuit board. The circuit board is encapsulated in epoxy, and a shielded four-conductor cable is connected to the circuit board to supply power, enable probe, and monitor the output.
The CS625 measures the volumetric water content of porous media (such as soil) using the time-domain measurement method; a reflectometer (cable tester) such as the TDR100 is not required. This method consists of the CS625 generating an electromagnetic pulse. The elapsed travel time and pulse reflection are then measured and used to calculate soil volumetric water content.
The signal propagating along the parallel rods of the CS625 is attenuated by free ions in the soil solution and conductive constituents of the soil mineral fraction. In most applications, the attenuation is not enough to affect the CS625 response to changing water content, and the response is well described by the standard calibration. However, in soil with relatively high soil electrical conductivity levels, compacted soils, or soils with high clay content, the calibration should be adjusted for the specific medium. Guidance for making these adjustments is provided in the operating manual.
|Measurements Made||Volumetric water content of porous media (such as soil)|
|Water Content Accuracy||±2.5% VWC (using standard calibration with bulk EC of ≤ 0.5 dS m-1, bulk density of ≤ 1.55 g cm-3, and measurement range of 0% to 50% VWC)|
|Required Equipment||Measurement system|
|Soil Suitability||Long rods and lower frequency are well-suited for soft soil with low electrical conductivity (< 2 dS/m).|
|Operating Temperature Range||0° to 70°C|
|Probe-to-Probe Variability||±0.5% VWC in dry soil, ±1.5% VWC in typical saturated soil|
|Output||0 to 3.3 V square wave (with frequency dependent on water content)|
|Power Supply Voltage||5 Vdc minimum; 18 Vdc maximum|
|Enable Voltage||4 Vdc minimum; 18 Vdc maximum|
|Electromagnetic||CE compliant (Meets EN61326 requirements for protection against electrostatic discharge.)|
|Rod Spacing||32 mm (1.3 in.)|
|Rod Diameter||3.2 mm (0.13 in.)|
|Rod Length||300 mm (11.8 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)|
|Weight||280 g (9.9 oz) without cable|
Please note: The following shows notable compatibility information. It is not a comprehensive list of all compatible products.
The RF emissions are below FCC and EU limits as specified in EN61326 if the CS625 is enabled less than 0.6 ms, and measurements are made less frequently than once a second. External RF sources can also affect the CS625 operation. Consequently, the CS625 should be located away from significant sources of RF such as ac power lines and motors.
The CS650G makes inserting soil-water sensors easier in dense or rocky soils. This tool can be hammered into the soil with force that might damage the sensor if the CS650G were not used. It makes pilot holes into which the rods of the sensors can then be inserted. It replaces both the 14383 and 14384.
Each CS625 requires a single-ended input channel. A control port is used to enable one or more probes.
Note: A maximum of four CS625 probes can be measured by one CR200(X) datalogger. Valid channel options are analog channels 1 through 4.
Number of FAQs related to CS625: 34
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300 m (1,000 ft).
Yes, as long as the data logger can detect a 0 to 3300 mV square wave over a frequency range of 29 to 67 kHz.
Yes. The PeriodAvg() CRBasic instruction may be used to measure the CS625 on a CR1000, CR800-series, or CR3000 datalogger. To make this work, it is important that the Threshold parameter be set to 1650 mV as shown in the following example:
PortSet (1 ,1 ) ‘Enable CS625 by setting C1 high (orange wire to C1)
PeriodAvg (PA_uS,1,mV250,1,1650,0,100,10,1.0,0) ‘Read Period on SE1 (green wire to SE1)
PortSet (1 ,0) ‘Disable CS625 by setting C1 low
Yes, but the CS616/CS625 will need a soil-specific calibration. The high organic matter content of peat will likely cause the CS616/CS625 period to be out of bounds for use with the CS616() CRBasic instruction and P138 Edlog instruction. In that situation, the CRBasic PeriodAvg() instructionor the Edlog P27 Period Average instruction may be used as described in the CS616 and CS625 instruction manual.
Fine roots do not significantly affect the CS616/CS625 reading.
Yes. For program examples and guidance on using a multiplexer with one of these reflectometers, see the CS616 and CS625 instruction manual.
The CS616/CS625 will survive frozen soil conditions, but the principle behind using bulk soil dielectric permittivity to estimate water content requires that the water be in liquid form. When soil water freezes, its dielectric drops from approximately 80 to 4, making it indistinguishable from soil solids. Consequently, the CS616/CS625 is not able to measure the water content of frozen soil.
Yes. The rugged design of the CS616/CS625 protects the probe electronics from water under these conditions. Many CS616/CS625 reflectometers have been working reliably in very wet conditions for more than ten years.
Cutting down rods should only be done at the user’s own risk. Doing so will cause the probe to need recalibration. Campbell Scientific does not provide calibrations for shorter rod lengths for the CS616 or the CS625.
With shorter rods, the probe will work, but there will be some reduction in accuracy because the length of the rod in the soil contributes a smaller proportion to the total transit time. However, probes with shorter rods will work in more saline soils.