MAS-1 4-20 MILLIAMP VOLUME SOIL MOISTURE Sensor

Measurements:

Applications:

4-20 Milliamp Output, Ultra-Long Cable Lengths

The MAS-1 4-20 milliamp sensor is the first current-based sensor to use Decagon's trademark 70 MHz technology. This sensor offers a standard 4-20 milliamp output that is common with PLCs and irrigation controllers.  With the 4-20 mA interface, cable lengths over 250 feet are possible. 

 

Research Grade Accuracy

The MAS-1 determines volumetric water content (VWC ) by measuring the dielectric constant of the media using capacitance/frequency domain technology. The sensor uses a 70 MHz frequency,  which minimizes salinity and textural effects, making the MAS-1 accurate in almost any soil or soil-less media. Factory calibrations are included for mineral soils, potting soils, and rockwool.

 

Low Cost Individual Sensors for Large Sensor Networks

The MAS-1 delivers research-grade accuracy at a price that makes large sensor networks economically practical. You can adequately characterize your site with sensors at multiple depths and locations, even if you're on a tight budget.

 

Advantages of the MAS-1

  • 4-20 milliamp sensor
  • Allows for cable lengths greater than 250 feet

INTERFACE

Standard 4-20 mA analog transmitter  

SUPPLY VOLTAGE

12-32 VDC continuous

OUTPUT CURRENT

4 - 20 mA

OVERVOLTAGE PROTECTION Yes
SETTLING TIME

4 seconds

WIRING

Red Wire: (+) supply

Black Wire: (-) output

Shield: not connected

SENSOR TYPE

Volumetric Water Content (VWC)

RANGE 0-100% VWC typical
RESOLUTION

Depends on current measurement (data aquistion) device

ACCURACY

±6% VWC with generic calibration for supported growing media up to 65% VWC, above which accuracy lessens.  Increased accuracy can be achieved with a medium-specific calibration.

OUTPUT

4-20 mA current proportional to VWC

SENSOR MEASUREMENT 
INTERVAL

1 second

OPERATING ENVIRONMENT
TEMPERATURE

-40 to 60°C*

*Sensors can be used at higher temperatures under some conditions.  Contact Decagon for more details.

PHYSICAL PROPERTIES 
DIMENSIONS

8.9 cm x 1.8 cm x 0.7 cm

CABLE

2 m or 5 m, 3 wire (22 AWG tinned Red and Black wire, 24 AWG tinned bare wire); custom cable length available upon request.

ANALOG SENSORS  
SENSOR EC-5 10HS GS1
MEASURES volumetric water content, dielectric permittivity volumetric water content, dielectric permittivity volumetric water content, dielectric permittivity
VOLUME OF INFLUENCE 240 mL 1320 mL 1430 mL
DATA LOGGER COMPATIBILITY Em5b, Em50, Em50G, ProCheck, ECH2O Check, Campbell Scientific* Em5b, Em50, Em50G, ProCheck, ECH2O Check, Campbell Scientific* Em5b, Em50, Em50G, ProCheck, ECH2O Check, Campbell Scientific*

MEASUREMENT RANGE

0 to 100% VWC 0 to 57% VWC 0 to 57% VWC
BEST IF

VWC is all that you need.

You're establishing a large sensor network.

You want a large measurement volume.

VWC is all that you need.

You're establishing a large sensor network.

You're installing in the side wall of a trench.

You need the most rugged sensor available.

BUT NOT IF You cannot apply a regulated voltage (only applies to non-Decagon data loggers).

You are measuring in nursery pots.

You are installing in rocky soil.

You are installing sensors down bore holes.

 

DIGITAL SENSORS  
SENSOR 5TM 5TE GS3 MAS-1  
MEASURES volumetric water content, dielectric permittivity, temperature volumetric water content, dielectric permittivity, temperature, electrical conductivity volumetric water content, dielectric permittivity, temperature, electrical conductivity volumetric water content  
VOLUME OF INFLUENCE 715 mL 715 mL 160 mL 450 mL  
DATA LOGGER COMPATIBILITY Em50, Em50G, ProCheck, Campbell Scientific*, SDI-12 capable Em50, Em50G, ProCheck, SDI-12 capable Em50, Em50G, ProCheck, SDI-12 capable Any logger with 4-m20 mA input (not compatible with Decagon data loggers or ProCheck)  

MEASUREMENT RANGE

0 to 100% VWC

-40 to 60 °C

0 to 100% VWC

-40 to 60 °C

0 to 23 dS/m

0 to 100% VWC

-40 to 60 °C

0 to 25 dS/m

0 to 100% VWC

-40 to 60 °C

 

BEST IF

Measure High temperature variability.

Data must be corrected for temperature effects.

Using SDI-12.

You are managing salts in your system.

You want to use SDI-12.

You are measuring water content of soilless substrates.

You need high accuracy EC.

You are working with a PLC with a 4-20 mA input.

You need extremely long cable lengths.

 

BUT NOT IF N/A You want to monitor soiless substrates or potting soils. You are installing sensors down bore holes.

You need to measure water content close to the soil surface.

You want to use Decagon data loggers or ProCheck.

You need a low-power system.

 

Compatibility and Programming Specifications for Campbell Scientific and Other (non-Decagon) Data Loggers

Note: ECH2O sensors are “plug and read” on Decagon data loggers. You do not need to program any of this information (or ANY information) into a Decagon logger.

SENSOR CAMPBELL COMPATIBILITY OTHER LOGGERS OUTPUT VOLTAGE REQUIREMENTS
EC-5 CR10X, 21X, 23X, CR1000, CR3000, etc. Any data acquisition system capable of switched 2.5 to 3.6 V excitation and single ended voltage measurement at 12 bit or better resolution. (Note: some people take their chances with resolution as low as 3 bits, but resolution lower than 10 bits will leave the data quite choppy). Voltage, correlated linearly (soil) or polynomially (growing media) with VWC 2.5-3.6 V
10HS CR10X, 21X, 23X, CR1000, CR3000, etc. Any data acquisition system capable of 3-15 VDC excitation and single ended voltage measurement at 12 bit or better resolution. Voltage correlated with VWC, independent of excitation 3-15 V
5TE Any logger with serial I/O (CR10X, CR850, CR1000, CR3000, etc.) Ask a Decagon representative for an integrator’s guide to interfacing the 5TE Digital ASCIII stream or SDI-12 3.6-15 V
5TM Any logger with serial I/O (CR10X, CR850, CR1000, CR3000, etc.) Ask a Decagon representative for an integrators guide to interfacing the 5TM Digital ASCII Stream or SDI-12 3.6-15 V
GS3 Any logger with serial I/O (CR10X, CR850, CR1000, CR3000, etc.) Ask a Decagon representative for an integrators guide to interfacing the GS3 Digital ASCII Stream or SDI-12 3.6-15 V
GS1 CR10X, 21X, 23X, CR1000, CR3000, etc. Any data acquisition system capable of 3-15 VDC excitation and single ended voltage measurement at 12 bit or better resolution. Voltage correlated with VWC, independent of excitation 3-15 V
MAS-1 Any logger with 4-20 mA output Any logger with 4-20 mA output 4-20 mA 12-32 VDC continuous